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Timing of onset of contraceptive effectiveness in norplant implant users. Part I. Changes in cervical mucus
FERTILITY
AND STERILITY@
VOL. 69, NO. 2, FEBRUARY 1998
Copyright 01998 American Society for Reproductive Medicine Published by Elsevier Science Inc. Printed on acid-free paper in U.S.A.
Timing of onset of contraceptive effectiveness in Norplant implant users. Part I. Changes in cervical mucus Thomas R. Dunson, M.S.,*-f Paul D. Blumenthal, M. D.,S Francisco Alvarez, M. D.,§ Vivian Brache, B.S.,§ Leila Cochon, B.S.,5 Barbara Da/berth, M.P.H., * Lucinda G/over, M.P.H.,* Robin Remsburg, Ph.D.,*11 Kenneth Vu, M.D.,$fl David Katz, Ph.D**
Received April 29, 1997; revised and accepted September 9, 1997. Norplant is a registered trademark of The Population Council, Inc. for subdermal contraceptive implants and is distributed by Wyeth-Ayerst, Philadelphia, PA. Reprint requests: Ms. Debbie Crumpler, P.O. Box 13950, Research Triangle Park, North Carolina 27709. * Clinical Trials Division and Biostatistics Division, Family Health International. t Worldwide Clinical Trials, 79 Alexander Drive, 4201 Building, Suite 101, P.O. Box 14166, Research Triangle Park, North Carolina 27709. $ Department of Obstetrics and Gynecology, Johns Hopkins Bayview Medical Center. 5 Biomedical Research Department, PROFAMILIA.
11 Gerontology Research, Johns Hopkins Bayview Medical Center. 1 Current address: Department of Medicine, Tripler AMC, Hawaii 966595000. * Department of Biomedical Engineering, Duke University.
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00150282/98/$19.00 PII SO0150282(97)00476-7
258
Family Health International, Research Triangle Park, North Carolina, Johns Hopkins Sayview Medical Center, Baltimore, Maryland, PROFAMILLA, Santo Domingo, Dominican Republic, and Duke University, Durham, North Carolina
Objective:
To provide scientific data regarding the changes in cervical mucus within the first hours to days after Norplant implant insertion and to estimate when the cervical mucus is hostile enough to suggest a contraceptive effect.
Design: Multicenter, Setting:
clinical descriptive
Family planning
study.
clinics.
Patient(s): Forty-two women who were between days 8 and 13 of their menstrual cycle and who had requested Norplant implants were admitted to the study. Intervention(s):
Cervical mucus and blood samples were obtained.
Main Outcome Measure(s): Cervical estradiol,
mucus scores,
sperm penetration
distances,
and serum levels of progesterone,
and levonorgestrel.
Result(s): The median cervical mucus score observed at baseline was 6 (“fair”), indicating that the mucus was already somewhat hostile before insertion of the Norplant implants. The median scores declined to 5 at 12 and 24 hours and continued to decrease through day 7 to 2 (“poor”), a score that is judged as hostile to sperm penetration. Overall, 73% of all subjects had a poor cervical mucus score by 3 days after insertion; at 7 days after insertion, 90% exhibited poor mucus and none had a good score. There was a substantial drop in the overall median distance traveled by the vanguard sperm after 12 hours for each cervical mucus score grouping. The distance traveled decreased rapidly between 12 and 24 hours to <0.5 cm in subjects with fair and poor mucus, and by day 3, 91% of the subjects exhibited poor sperm penetration. Conclusion(s): On the basis of our findings, deterioration of the quality of the cervical mucus and sperm penetration is evident by 24 hours after insertion, although not to a level that would suggest adequate protection until 72 hours after insertion. Therefore, we are confident in recommending that backup methods of contraception (e.g., condoms) need not be used for more than 3 days after insertion, even when the implants are inserted close to ovulation. These findings provide policy makers, clinic managers, and clinicians with important information about how they can improve client access to Norplant implants. (Fertil Steril @ 1998;69:258-66. 01998 by American Society for Reproductive Medicine.)
Key Words: estradiol,
Norplant, levonorgestrel
cervical
mucus, sperm penetration
For progestin-only contraceptive methods such as Norplant implants (The Population Council, Inc., New York, NY) and progestinonly pills, changes in cervical mucus are considered to be a very important factor in pre-
distance,
contraception,
backup contraception,
progesterone,
venting pregnancy (1). At approximately the ninth day of an ovulatory menstrual cycle, the cervical mucus becomes thin, watery, and receptive to sperm penetration, and the penetrability increases to a peak just before ovulation
(2). With increasing serum progesterone concentrations after ovulation, the cervical mucus becomes scanty, thick, opaque, and unfavorable for sperm penetration, and sperm penetration diminishes. The time and degree of sperm penetrability vary among individuals. Administration of progestinonly contraceptives simulates these naturally occurring effects (3). Few studies have been conducted to evaluate the effect of Norplant implants on cervical mucus. In these studies, cervical mucus from implant users was found to be scanty and viscous even during regular menstrual cycles. In vitro examination showed sperm penetration to be markedly poorer in mucus collected from implant users than in mucus from matched control subjects not using hormonal contraceptives (4). Postcoital tests in another study of Norplant users indicated that few sperm reached the cervital canal, and those that did had reduced motility (5). A third study found that after implant removal, despite the rapid return of ovulation (within 4 weeks for 87% of the women), fertilization may be delayed because the cervical mucus remains poor, as measured by quantity, spinnbarkeit, and ferning (6). With respect to onset of action, Norplant implants are reported to be effective within a few hours of insertion, with blood levels of levonorgestrel being sufficient to prevent conception by 24 hours (7, 8). To date, however, there have been no data published confirming this time sequence. Even though the exact mechanism by which levonorgestrel prevents conception has not been defined completely, the contraceptive action is most probably a combination of at least two effects: suppression of ovulation and thickening of the cervical mucus (7,8). With changes in cervical mucus being an important component of the overall mechanism of action, the rapidity and reliability of these changes have important programmatic implications. Indeed, the protocols that guide clinicians as to when in a menstrual cycle Norplant implants can be inserted and the length of time patients will be required either to abstain or to use backup contraception (e.g., condoms) are based, in great measure, on an understanding of this effect as shown for progestin-only pills and natural progesterone (9, 10). This study was conducted to document better the cervical mucus changes within the first hours to days after Norplant implant insertion and to estimate when the cervical mucus is hostile enough to suggest contraceptive effect. These data should provide scientific evidence on the length of time that backup contraception is needed after insertion, particularly for those women having insertions performed in the late preovulatory or early periovulatory phase. This report represents the first in a series of articles that will report on these cervical mucus changes. FERTILITY & STERILITY@
MATERIALS AND METHODS Study Population Subject enrollment began at two clinical sites, PROFAMILL4 in Santo Domingo, Dominican Republic and the Johns Hopkins Bayview Medical Center in Baltimore, Maryland, in October 1994 and December 1994, respectively. Enrollment was completed at both sites in September 1995 after a total of 42 healthy female volunteers aged 18-40 years were enrolled. All subjects had a normal history and physical examination, had not used hormonal contraception in the 4 months before entering the study and did not have a recent history of pregnancy (<3 months postpartum). Subjects were between days 8 and 13 (inclusive) of their current menstrual cycle on the insertion date and had sufficient cervical mucus for evaluation 22 hours before implant insertion. Finally, the subjects were required to be abstinent for 48 hours before insertion and agreed to abstain from coitus or to use a nonspermicidal condom for the duration of the _ study. After being informed about the purpose of the study and the risks and benefits associated with the use of this contraceptive method, the subjects gave informed consent in accordance with the requirements for this Institutional Review Board-approved protocol. Every woman admitted to the study was specifically advised that the implants could be removed, if she so desired, at any time in the same clinic.
Subject Assessments The subjects made up to seven clinic visits (screening, admission, and 5 follow-up visits). Subjects in Baltimore spent the first 24 hours in the General Clinical Research Center, whereas subjects in the Dominican Republic returned to the clinic at the specified follow-up times during this initial period. Cervical mucus samples were taken for scoring and for in vitro mucus penetration testing, and blood was drawn for evaluation of serum progesterone and estradiol concentrations before insertion. The implants then were inserted using the standard insertion technique. Follow-up visits were held in the clinic at 6, 12, and 24 hours after insertion and on days 3 and 7 after insertion for subsequent cervical mucus sampling and blood sampling (an aliquot also was used for levonorgestrel evaluation after insertion). A subject was considered to have completed the study if she returned to tbe clinic for her day 7 follow-up visit and completed the procedures at this visit.
Cervical Mucus Collection Cervical mucus was collected according to the WHO Laboratory Manual for the Examination of Human Semen and Sperm-Cervical Mucus Interaction (11). A cervical cath-
eter was constructed from polyethylene tubing and attached to a lo-mL syringe. A speculum was inserted into the vagina and the appearance of the cervix and the external OS was 259
examined, along with the amount of mucus present at the OS. The external OS was wiped gently with a moist cotton swab to remove the external pool of vaginal contaminants. With the use of forceps, the catheter tip was inserted l-2 cm into the cervical canal. Once the catheter was positioned, gentle suction was applied with the syringe to aspirate mucus. Once sufficient mucus was aspirated to perform the required tests, the catheter was removed. (If insufficient mucus was present, the tests were not performed, and both the cervical mucus score and the vanguard sperm penetration distance were assigned a “0” value.) The catheter was then disconnected from the syringe and cut into two pieces. The sample of cervical mucus in the piece most distal from the syringe was evaluated. The mucus sample in the remaining catheter (just proximal to the syringe) was prepared for the mucus penetration test, or both ends of this piece of the catheter were sealed with Critoseal (Sherwood Medical Industries, Inc., St. Louis, MO), labeled appropriately, and refrigerated at 4°C for subsequent testing within 5 days of collection.
Evaluation
and Scoring of Cervical Mucus
The cervical mucus was evaluated and scored during collection of the mucus by a single observer at each site. We followed the guidelines of the World Health Organization (11) for evaluating and scoring the mucus, which were, in turn, based on the original system proposed by Insler et al. (12). Variables evaluated included spinnbarkeit, consistency, cellularity, and feming. The volume component was excluded from evaluation in this study, yielding a total score of 12 as opposed to a total score of 15 as per the usual guidelines (11). We excluded the volume measurement because, to determine the actual mucus volume, the entire amount of mucus present would have to be aspirated. Because the rate of mucus production is unknown, we could not be certain whether the amount of mucus produced between the O-hour and 6-hour or the 6-hour and 12-hour time periods would accurately reflect normal mucus production or would be decreased by the action of levonorgestrel. Therefore, we believed that including the volume component would not yield accurate results. The sum of scores for the four variables produced the cervical mucus score, which could range from 0 to 12. For the purposes of this analysis, we chose to group the scores within this range into three categories. A score of O-4 indicated poor mucus conditions; 5-8 was considered fair; and a score of 9-12 was considered good, indicating mucus capable of good sperm penetration. Using the scoring system of the World Health Organization, a score >lO usually indicates good cervical mucus favoring sperm penetration, and a score ~10 may represent unfavorable mucus. Justification for the classification of the World Health Organization as well as that proposed by Insler et al. (12) was not given. We believe that our classification system, although
260
Dunson et al.
Timing of effectiveness
of Norplant implants
subjective, tems.
is sound and compares
In Vitro Mucus Penetration
favorably
with past sys-
Test
In this study, we used a flat capillary tube to contain cervical mucus during testing of sperm penetrability. The tube was 3 mm X 0.3 mm in cross-section and was cut to a length of 2-3 cm. This length is shorter than the common 5-cm length used in most contemporary research studies of mucus (13-17) and the lo-cm length described by the World Health Organization. The reduced length was necessary to accommodate the small specimen volumes of mucus collected in this study. The mucus specimens collected would not have filled longer tubes, and the uncontrolled technical artifacts induced by incomplete filling of tubes with mucus would have obfuscated interpretation of these experiments. In capillary tube tests of sperm penetration, the exposure interval of semen to mucus depends upon tube length. If the interval is too long, sperm will fill the entire tube under conditions of good penetration, and vanguard penetration distance will not be directly measurable. The common exposure interval is 30 minutes at 37°C for a tube 5 cm in length (13-17); for the lo-cm tube, the World Health Organization recommended interval is 60 minutes. In the present study, the exposure time was 30 minutes. Fresh semen was used 51 hour after ejaculation. While the mucus penetration test was being run, a semen analysis was performed to determine the volume of the ejaculate, the concentration of sperm in a sample of uniformly mixed semen, and the percentage of sperm demonstrating motility. Because motility was used to estimate viability (i.e., was not used to determine fertilizing potential), motility was defined as any demonstration of movement, regardless of the presence of forward progression. The percentage of sperm demonstrating progressive forward motility also was determined. Except for the definition for motility, the semen analysis was performed using a Neubauer hemocytometer according to the guidelines of the World Health Organization (11). The mucus penetration test was designed to assess both the penetration distance of the vanguard sperm in the mucus and the overall numbers of penetrating spermatozoa. These two measures of penetration were retained as distinct variables. During performance of the test, the numbers of motile and nonmotile sperm were counted at every 0.5 cm (for a total of up to 5 positions), and the position of the vanguard sperm was noted. Vanguard penetration distance was measured directly for tests in which sperm had not penetrated the entire length of the mucus column. In some cases, sperm penetrated the entire length of the mucus column and we could not be certain how far they would have traveled in a longer mucus column. In this case, vanguard penetration distance was estimated by fitting the counts of sperm numbers versus position along the tube (i.e., distance from the semen-mucus interface) to an exponential
Vol. 69, No. 2, February
1998
function (16, 18). Penetration distance then was defined as the distance from the semen-mucus interface at which the exponential function predicted a count of one sperm; this is analogous to the paradigm used by Aitken et al. (16). Our paradigm thus predicted how far the vanguard sperm would have penetrated if the column of mucus had been much longer (i.e., so that sperm had not traversed the entire length of the mucus column). For this analysis, we chose to use a vanguard sperm penetration distance of < 1 .O cm as a cutpoint for contraceptive effect. A distance of < 1.O cm was chosen because, in all but one subject with poor cervical mucus at baseline, the vanguard sperm penetration at baseline was -=L1.O cm; conversely, no subjects exhibited a good cervical mucus score at baseline when baseline sperm penetration was cl.0 cm. If the sperm penetration scoring system of the World Health Organization had been used, the score for vanguard sperm penetration would be “0” when sperm penetration was c3.0 cm. Given the technical differences in methodology between our system and that of the World Health Organization, we believe that our score is more conservative.
Cervical Mucus Changes Originally, we intended to analyze the changes in cervical mucus by grouping the subjects by cycle day of insertion. However, our results indicated that the chronological day of the cycle did not always correlate with the functional date of the cycle because of individual variations in the length of the follicular phase. Therefore, we considered that the most logical and appropriate way to study the changes in cervical mucus was by grouping the subjects by baseline value of cervical mucus (poor, fair, or good) rather than by chronological date.
Hormone Assays Blood was drawn at various times throughout the study for hormonal assays. The methods and results of these assays and their relation to cervical mucus and ovarian function will be detailed in subsequent articles in this series.
RESULTS Most women (54.8%) in this study had the implants inserted on days 12 and 13 of their menstrual cycle (data not shown). Originally, recruitment efforts were focused on evenly distributing volunteers along the 5 days of study (e.g., 10 subjects admitted on day 8, 10 subjects on day 9, and so on). However, it soon became apparent that few of the women had evaluable cervical mucus on day 8. Thus, the distribution of subjects by day of the menstrual cycle was uneven. The mean age of the study subjects was 23.8 years and the average weight was 57.9 kg. Table 1 shows the cervical mucus scores found before Norplant implant insertion, classified according to day of the cycle and stratified by quality at baseline as poor (O-4), fair
FERTILITY
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Percentage of women in each baseline cervical mucus group stratified by cycle day. Cycle day Baseline cervical mucus group Poor (o-4) Fair (5-8) Good (9-12)
8/9 (n = 6)
10/l 1 (n = 13)
12/13 (n = 23)
61 33 0
23 23 54
26 39 35
Note. Data are given as percentages.
(5-8), and good (9-12). As expected, most mucus samples on days 8 and 9 were poor (67%), and none had a good score. The cervical mucus samples collected between days 10 and 11 and 12 and 13 were somewhat more uniform, with 77% and 74%, respectively, exhibiting fair or good quality. On days 10 to 11, 54% of the cervical mucus samples were scored as good, compared with 35% of those samples taken on days 12 to 13. When the median cervical mucus scores were observed over time and stratified by quality of the mucus at baseline (Fig. l), subjects with good cervical mucus at baseline exhibited a median score at baseline of 10, which decreased to 6 (fair mucus) by 24 hours and to 3.5 (poor mucus) by day 3. It was noteworthy that subjects with poor mucus at baseline experienced a rise in mucus quality during the 1Zhour period after insertion; however, a change back to poor mucus was observed by 24 hours. The overall median cervical mucus score seen at baseline was 6 (of a possible total score of 12) indicating that, for at least these subjective observations, the mucus was somewhat hostile before insertion of Norplant (data not shown). This overall score declined to 5 at 12 and 24 hours and continued to decrease through day 7 to 2, a score that is judged as hostile to sperm penetration using the standard criteria of the World Health Organization. Most subjects (>70%) demonstrated mucus of poor quality (O-4) by day 3 of the study, regardless of the quality of their mucus at baseline (Table 2). Of those subjects who exhibited fair mucus at baseline, 71% exhibited poor mucus by day 3 and 100% by 7 days after insertion. Collectively, by day 3, 73% of the subjects had a poor cervical mucus score and by day 7,90% exhibited mucus of poor quality; only one subject on either of these days exhibited a good score. As shown in Figure 2, there was a substantial drop in the overall median distance traveled by the vanguard sperm (in centimeters) after 12 hours for each cervical mucus score grouping. There was an increase in the median distance traveled between baseline and 6 hours for each grouping, and it continued to increase through 12 hours for those subjects with poor mucus at baseline. The median distance traveled decreased rapidly between 12 and 24 hours to CO.5 cm in
261
Median cervical mucus scores by cervical mucus score at baseline at each time point.
-o-
Poor cervical mucus at baseline (O-4)
t
Fair cervical mucus at baseline (5-8)
-Good
0
I I
I I
0612
I I
I I
24
3
Hour
cervical mucus at baseline (9-12)
I 7
Day
Day
Follow-up
subjects with fair and poor mucus, and to 1.0 cm in those with mucus considered to be good. The distance traveled decreased or remained consistently suppressed for all groups until reaching a median distance of 0 by day 7. As expected, the initial distance traveled by the vanguard sperm was greater for those subjects with good mucus and was less for the other two groups.
Period
Table 2 also shows the percentage of subjects demonstrating poor vanguard sperm penetration at different time points stratified by the cervical mucus score at insertion. Poor sperm penetration was defined as any penetration of < 1.0 cm. Consistent with the findings for cervical mucus scores, the percentage of subjects with poor vanguard sperm penetration decreased through 12 hours, with the exception of
Percentage of women achieving poor cervical mucus and poor sperm penetration stratified by baseline cervical mucus group at each time point. Time point Baseline cervical mucus group
Oh
No. of women with poor cervical mucus/no. women studied (%) Poor (O-4) Fair (5-8) Good (9-12) Overall No. of women with poor sperm penetration (Cl.0 cm)/no. of women studied (%) Poor (OA) Fair (5-8) Good (9-12) Overall
6h
12 h
24 h
Day 3
Day I
of 13/13 o/14 o/15 13/42
(100) (0) (0) (31)
Ill 3 o/14 l/15 8/42
(54) (0) (7) (19)
6113 4114 2/14 12/41
(46) (29) (14) (29)
9112 3114 3/15 15/41
(75) (21) (20) (37)
10/13 10/14 10/14 30/41
(77) (71) (71) (73)
10/13 14/14 14/15 38/42
(77) (100) (93) (90)
12/13 6114 o/15 18/42
(92) (43) (0) (43)
9113 3114 l/14 13/41
(69) (21) (7) (32)
7/l 1 (64) 4114 (29) 1114 (7) 12I39 (31)
1 l/12 10/13 6115 27140
(92) (77) (40) (68)
900 11111 12/14 32/35
(90) (100) (86) (91)
lo/12 13/14 14/14 37/40
(83) (93) (100) (93)
Note. The denominators for the sperm penetration test and mucus sample may differ because the sperm penetration adequately or the mucus sample was contaminated or was not collected within the specified time limits.
distance
262
Vol. 69, No. 2, February 1998
Dunson et al.
Timing
of effectiveness
of Norplant
implants
could not be determined
Median vanguard sperm distance by cervical mucus score at baseline at each time point.
+-Good
0612
24 Hour
3
7
Day
Day
Follow-up
those subjects with good cervical mucus at baseline; an increase was observed for these subjects. The percentage of subjects with poor penetration increased between 12 and 24 hours after insertion and remained high through day 7. Subjects with good mucus quality at baseline demonstrated increasingly poor penetration at all observation points. Overall, at day 3, 32 of 35 women (91%) had poor penetration, and at day 7, 37 of 40 (93%) had poor sperm penetration. Because all of the variables examined in this study are subject to individual variation, we reviewed the results by individual, particularly for day 3 and day 7; a description of some of these data follows. One subject’s mucus, which was poor at baseline, improved to good (9) by day 3 with a vanguard sperm penetration of 1.0 cm; however, by day 7, there was insufficient mucus to analyze the sample. Another subject, whose mucus quality was poor at baseline, exhibited good mucus at day 7 with a vanguard sperm penetration of 2.5 cm. However, the results at this time point are questionable, given that all prior mucus scores were poor or fair (highest = 8) and the vanguard sperm penetration was 5 1.O cm. In addition, hormone levels for this subject were consistent with contraceptive effect at each time point evaluated. In addition, we further examined individual data for subjects who exhibited good cervical mucus quality at any
FERTILITY
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cervical mucus at baseline (9-12)
Period
time point during the study. Eleven of 15 subjects who exhibited good cervical mucus at baseline demonstrated poor mucus by day 3; the four exceptions scored as fair (5-6). All but one subject whose mucus was good at baseline were scored as poor by day 7; the exception was scored as fair (5). No subjects who had good cervical mucus had poor sperm penetration (< 1.O cm) at any time point. Finally, we examined individuals who had both a good cervical mucus score and a sperm penetration other than poor (2 1.0 cm) at any time point. Although there were several subjects who matched these criteria at 0 and 6 hours, we found only two subjects who fulfilled these criteria at 24 hours, and one each at days 3 and 7. The subjects at days 3 and 7 were the same individuals discussed previously. Although detailed changes in serum hormone levels will be reported in a subsequent article, we observed that deterioration of cervical mucus and sperm penetration occurred uniformly in all subjects regardless of their hormonal status (i.e., some women ovulated after insertion, as judged by increased progesterone levels, whereas some had high preovulatory estradiol levels without an elevation in progesterone).
263
Percentage
distribution
of vanguard
sperm penetration
at each time point and long-term
use results.
Time point
Penetration
distance (cm)
Insufficient SO.05
mucus
0.6-1.0 1.1-1.5 1A-2.0 >2.0
6h
12 h
24 h
Day 3
Day 7
Long term*
(n “=“,2)
(n = 41)
(n = 39)
(n = 40)
(n = 3.5)
(n = 40)
(n = 16)
0 43
0 22
0 15
3 63
9 80
28 65
31 44
I 5 10 36
20 7 20 32
28 21 10 26
13 10 8 5
9 3 0 0
0 5 0 3
12 6 6 0
No&. Missing values resulted when the sperm penetration not collected within the specified time limits. * Data for long-term use were abstracted (4).
distance could not be determined
DISCUSSION Norplant implants have now been approved and available in the United States for >6 years and for a longer period in other countries. During this time, a variety of guidelines have been proposed that assist clinicians in determining when in a menstrual cycle Norplant implants can be inserted and to what extent a backup method (e.g., condoms) may be required (19,20). Experts developing these guidelines have based their recommendations, in part, on an understanding of the hypothesis that, when exposed to progestin, the cervical mucus changes rapidly and consistently enough to form a sperm block within a few hours to a few days after insertion. However, because few studies have attempted to examine this effect rigorously, clinical decisions regarding insertion timing and the need or duration for a backup method when insertions occur after day 7 of the menstrual cycle have been based largely on supposition and personal interpretations of what few data are available. Data presented in this report support the finding that progestin-only contraceptives cause profound alterations in the properties of human cervical mucus and, in the case of Norplant implants, interfere with the migration of sperm through the mucus. The physical properties of cervical mucus (e.g., spinnbarkeit, ferning) that are important in the sperm-cervical mucus interaction have been shown to be influenced adversely by progestational agents (21-24). We observed similar effects in this study, as all cervical mucus parameters indicated a hostile cervical mucus soon after insertion of Norplant implants. Overall, mucus quality deteriorated rapidly after 24 hours and could be considered hostile to sperm penetration by day 3. In a normally ovulating woman, the cervical mucus generally remains hostile until day 8 or 9 of the menstrual cycle (25). Our results indicated this to be true, as most samples collected on these days were judged to be of poor quality. Furthermore, mucus quality deteriorated over time in most subjects regardless of which day of the cycle insertion occurred.
264
Dunson et al.
Timing of effectiveness of Norplant implants
adequately
or when the mucus sample was contaminated
or was
Sperm penetration was inhibited in most subjects by 24 hours. Similar results have been reported previously for other progestin-only methods (26-29). Our data show that vanguard sperm penetration decreased rapidly between 12 and 24 hours, particularly in those subjects with good and fair mucus quality at baseline. We observed an increase in the median distance traveled between baseline and 6 hours for all cervical mucus groups at baseline and through 12 hours for those subjects with poor mucus at baseline; however, we have no explanation for this finding. After 24 hours, sperm penetration either remained suppressed or continued to decrease throughout the study, with 91% of the subjects demonstrating a sperm penetration of < 1.O cm by day 3 and 93% by day 7, a result that suggests impaired fertility. In a recent study, Barbosa et al. (30) observed the relation between Uniplant insertion and changes in cervical mucus. The progestin in this implant was observed to affect cervical mucus production and sperm penetration 24 hours after implant insertion in 71% of the women studied; mucus production and sperm penetration were affected in all women by 48 hours. The results we obtained at day 3 after insertion are very similar to those reported in a study of long-term Norplant implant users, in which a reduction in the amount of cervical mucus and impairment of sperm penetration were found regardless of the length of use, day of cycle, or endocrine pattern at the time of sampling (4). Table 3 illustrates that, in the study of long-term users, none of the subjects had a vanguard sperm penetration distance >2 cm, whereas 12% had a vanguard sperm penetration distance > 1.0 cm but 52.0 cm. None of the subjects in our study had sperm penetration >2 cm, and only 3% had a penetration distance Cl.0 cm but 52.0 cm at day 3 after insertion. Thus, by day 3, the deterioration in cervical mucus is similar to what is attained during long-term use. Given that a high percentage of women ovulate during long-term use of Norplant implants despite a high level of
Vol. 69, No. 2, February 1998
effectiveness, we can infer that we may have comparable contraceptive effectiveness by day 3 of use. However, we should note that other subtle endocrine changes have been reported in ovulatory cycles during long-term use, such as blunted LH peaks and diminished progesterone levels, which also may contribute to the contraceptive effect (31). We cannot be certain that these changes occur when the development of the follicle has taken place without the continuous influence of levonorgestrel, and the implants are inserted late in the follicular phase. However, in a recent study in which the implants were inserted in the preovulatory phase, the LH surge in that cycle was also blunted, as has been reported in long-term use (32). Overall, our data are comparable to the findings of Petta et al. (33), who used the same study design in Depo-Provera users. Although similar results are described, their findings suggest that contraceptive effect may not be established fully in Depo-Provera users until day 3 after injection. This conclusion is based on the fact that one subject at day 3 was observed to have mucus of good quality, a vanguard sperm penetration of 2.5 cm, and a high motile sperm count. Although by day 7, all parameters were negative, these authors chose a very conservative approach on the basis of this subject’s findings at day 3. The current study was conducted to explore objectively the nature of the relation between Norplant implant insertion and cervical mucus changes and to provide clinicians with objective data for use in clinical decision making. As a result, clinicians should be more confident with, and clients might have more convenient access to, this contraceptive. These data provide policy makers, clinic managers, and clinicians with important information about how they can improve client access to Norplant implants. Our data indicate that backup protection for the entire cycle is not necessary given the profound effect of levonorgestrel on the cervical mucus shortly after insertion, even in the event of possible ovulation. Although there are no clear absolute values for cervical mucus changes or sperm penetration that can be correlated directly to contraceptive effectiveness, our data indicate deterioration in the quality of cervical mucus and sperm penetration by 24 hours after insertion, and this deterioration was severe enough by 72 hours after insertion to suggest impaired fertility indicative of contraceptive effectiveness. Therefore, we conclude that backup methods of contraception such as condoms need not be used for >3 days after insertion, even when the implants are inserted close to ovulation.
Acknowledgmenrs: Partial support for this work was provided by Family Health International with funds from the U.S. Agency of International Development (USAID), although the views expressed in this article do not
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& STERILITY@
necessarily reflect those of USAID. Family Health International is an international nonprofit organization that conducts research and provides technical assistance in reproductive health, family planning, sexually transmitted diseases, and AIDS. It is based in Research Triangle Park, North Carolina. We extend a special note of appreciation to Noel McIntosh, who provided ideas that were germinal to this project.
References 1. Li XF, Newton J. Progestogen-only contraceptives and ectopic pregnancy. Br J Fam Plann 1992;18:79-84. 2. Moghissi K, Marks C. Effects of microdose Norgestrel on endogenous gonadotropic and steroid hormones, cervical mucus properties, vaginal cytology, and endometrium. Fertil Steril 1971:21:425-34. 3. Moghissi KS, Syner FN, McBride LC. Contraceptive mechanism of microdose norethindrone. Obstet Gynecol 1973;41:585-94. 4. Croxatto HB, Diaz S, Salvatierra AM, Morales P, Ebensperger C, Brandeis A. Treatment with NORPLANT@ subdermal implants inhibits sperm penetration through cervical mucus in vitro. Contraception 1992;36:193-201. 5. Brache V, Falindes A, Johansson E, Alvarez F. Anovulation, inadequate luteal phase and poor sperm penetration in cervical mucus during prolonged use of NORPLANT@ implants. Contraception 1985;31:26113. 6. Konje J, Otolorin E, Odukoya 0, Ladipo 0. Return of ovulation after removal of Norplant@ subdermal implants. Br J Fam Plann 1992;18: _ 44-6. 7. Population Council. Norplant levonorgestrel implants: a summary of scientific data. New York: The Population Council, 1980. 8. Sivin I. International experience with Norplant@ and Norplant-2@ contraceptives. Stud Fam Plann 1988; 19:81-94. 9. Martinez-Manautou J, Giner-Velasquez J, Cortes-Gallegos V, Aznar R, Rojas B, Guiterrez-Najar A, et al. Daily progestogen for contraception: a clinical study. Br Med J 1967;2:730-2. 10. Kesseru-Koos E. Influence of various hormonal contraceotives on sperm migration in vivo. Fertil Steril 1971;22:584-603. 11. World Health Organization. WHO laboratory manual for the examination of human &men and sperm-cervical-mucus interaction. Cambridge, UK: Cambridge University Press; 1992. 12. Insler V, Melmed H, Eichenbrenner I, Serr DM, Lunenfeld B. The cervical score: a simple semiquantitative method for monitoring of the menstrual cvcle. Int J Gvnaecol Obstet 1972;10:223-8. 13. Katz DF, dverstreet JAW, Hanson FEW. A new quantitative test for sperm penetration into cervical mucus. Fertil Steril 1980;33:179-86. 14. Katz DF, Overstreet JAW, Tom RA, Hanson FEW. Factors influencing the penetration of human spermatozoa into cervical mucus in vitro. Gamete Res 1984;9: 167-74. 15. Sharman D, Chanter E, Duykes M, Hutchinson FG, Elstein M. Comparison of the action of nonoxynol-9 and chlorhexidine on sperm. Fertil Steril 1986;45:259-64. 16. Aitken RJ. Bowie H. Buckineham D, Harkisss D. Richardson DW, West KM. Sperm penetration &to a hyaluronic acid polymer as a means of monitoring functional competence. J Androl 1992;13:44-54. 17. Achatya U, Irvine DS, Hamilton MPR, Templeton AA. The effect of three -anti-oestrogen drugs on cervical mucus quality and in-vitro soerm-cervical mucus interaction in ovulatorv women. Hum Reurod i993;8:437-41. 18. Lee WI, Gaddum-Rosse P, Blandau RJ. Sperm penetration into cervical mucus in vitro. III. Effects of freezing on estrous bovine cervical mucus. Fertil Steril 1981;36:209-13. 19. McIntosh N, Riseborough P, Davis C, editors. JHPIEGO Corporation. Norplant guidelines for family planning service programs. 2nd ed. Baltimore, MD JHPIEGO, 1993. 20. Curtis KM, Bright PL, editors. Technical Guidance Working Group. Recommendations for updating selected practices in contraceptive use: results of a technical meeting. 1994. 21. Moghissi KS. Cyclic changes of cervical mucus in normal and progestin treated women. Fertil Steril 1966;17:663-75. 22. Gibor Y, Cohen MR, Scommegna A. Effect of continuous administration of small doses of chlormadinone acetate on the cervical mucus and postcoital test. Fertil Steril 1969;20:572-80. 23. Roland M, Friedman M, Hessekiel RJ. Norgestrel, a low-dose oral progestogen for fertility control. Obstet Gynecol 1967;31:637-42. 24. Martinez-Manautou .I, Cortez V, Giner J, Aznar R, Casasola J, Rude1 HW. Low dose progestin as an approach to fertility control. Fertil Steril 1966;17:49-57. 25. Moghissi KS. A composite picture of the menstrual cycle. Am J Obstet Gynecol 1972;114:405-18. 26. Kremer J. A simple sperm penetration test. Int J Fertil 1965;10:209-15. 27. Gutierrez-Najar A, Giner-Velazquez J, Martinez-Manautou J. Role of
265
cervical mucus in contraception with the continuous chlormadinone acetate method. Adv Plann Parenthood 1969;4:97-102. 28. Lebech PE, Svendsen PA, Ostergaard E, Koch F. The effects of small doses of megestrol acetate on the cervical mucus. Acta Obstet Gynecol Stand 1969;3:22-35. 29. Aref I, Hefnawi F, Kandil 0, Aziz MT. Effect of minipills on physiologic responses of human cervical mucus, endometrium, and ovary. Fertil Steril 1973;24:578-83. 30. Barbosa IC. Coutinho E. Hirsch C, Ladiuo OA, Olsson SE, Ulmsten U. Temporal relationship between Uniplani insertion and changes in cervical mucus. Contraception 1996;54:213-7.
266
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of Norplant implants
31. Faundes A, Brache V, Tejada AS, Cochon L, Alvarez-Sanchez F. Ovulatory dysfunction during continuous administration of low-dose levonorgestrel by subdermal implants. Fertil Steril 1991;56:2731. 32. Brache V, Alvarez F, Faundes A, Cochon L, Thevenin F. Effect of preovulatory insertion of Norplant implants over luteinizing hormone secretion and follicular development. Fertil Steril 1996;65: 1110-4. 33. Petta CA, Faundes A, Dunson TR, Ramos M, DeLucio M, Faundes D, et al. Timing of onset of contraceptive effectiveness in Depo-Provera users. I. Changes in cervical mucus. Fertil Steril 1998;69:252-7.
Vol. 69, No. 2, February
1998
AND STERILITY@
VOL. 69, NO. 2, FEBRUARY 1998
Copyright 01998 American Society for Reproductive Medicine Published by Elsevier Science Inc. Printed on acid-free paper in U.S.A.
Timing of onset of contraceptive effectiveness in Norplant implant users. Part I. Changes in cervical mucus Thomas R. Dunson, M.S.,*-f Paul D. Blumenthal, M. D.,S Francisco Alvarez, M. D.,§ Vivian Brache, B.S.,§ Leila Cochon, B.S.,5 Barbara Da/berth, M.P.H., * Lucinda G/over, M.P.H.,* Robin Remsburg, Ph.D.,*11 Kenneth Vu, M.D.,$fl David Katz, Ph.D**
Received April 29, 1997; revised and accepted September 9, 1997. Norplant is a registered trademark of The Population Council, Inc. for subdermal contraceptive implants and is distributed by Wyeth-Ayerst, Philadelphia, PA. Reprint requests: Ms. Debbie Crumpler, P.O. Box 13950, Research Triangle Park, North Carolina 27709. * Clinical Trials Division and Biostatistics Division, Family Health International. t Worldwide Clinical Trials, 79 Alexander Drive, 4201 Building, Suite 101, P.O. Box 14166, Research Triangle Park, North Carolina 27709. $ Department of Obstetrics and Gynecology, Johns Hopkins Bayview Medical Center. 5 Biomedical Research Department, PROFAMILIA.
11 Gerontology Research, Johns Hopkins Bayview Medical Center. 1 Current address: Department of Medicine, Tripler AMC, Hawaii 966595000. * Department of Biomedical Engineering, Duke University.
??
00150282/98/$19.00 PII SO0150282(97)00476-7
258
Family Health International, Research Triangle Park, North Carolina, Johns Hopkins Sayview Medical Center, Baltimore, Maryland, PROFAMILLA, Santo Domingo, Dominican Republic, and Duke University, Durham, North Carolina
Objective:
To provide scientific data regarding the changes in cervical mucus within the first hours to days after Norplant implant insertion and to estimate when the cervical mucus is hostile enough to suggest a contraceptive effect.
Design: Multicenter, Setting:
clinical descriptive
Family planning
study.
clinics.
Patient(s): Forty-two women who were between days 8 and 13 of their menstrual cycle and who had requested Norplant implants were admitted to the study. Intervention(s):
Cervical mucus and blood samples were obtained.
Main Outcome Measure(s): Cervical estradiol,
mucus scores,
sperm penetration
distances,
and serum levels of progesterone,
and levonorgestrel.
Result(s): The median cervical mucus score observed at baseline was 6 (“fair”), indicating that the mucus was already somewhat hostile before insertion of the Norplant implants. The median scores declined to 5 at 12 and 24 hours and continued to decrease through day 7 to 2 (“poor”), a score that is judged as hostile to sperm penetration. Overall, 73% of all subjects had a poor cervical mucus score by 3 days after insertion; at 7 days after insertion, 90% exhibited poor mucus and none had a good score. There was a substantial drop in the overall median distance traveled by the vanguard sperm after 12 hours for each cervical mucus score grouping. The distance traveled decreased rapidly between 12 and 24 hours to <0.5 cm in subjects with fair and poor mucus, and by day 3, 91% of the subjects exhibited poor sperm penetration. Conclusion(s): On the basis of our findings, deterioration of the quality of the cervical mucus and sperm penetration is evident by 24 hours after insertion, although not to a level that would suggest adequate protection until 72 hours after insertion. Therefore, we are confident in recommending that backup methods of contraception (e.g., condoms) need not be used for more than 3 days after insertion, even when the implants are inserted close to ovulation. These findings provide policy makers, clinic managers, and clinicians with important information about how they can improve client access to Norplant implants. (Fertil Steril @ 1998;69:258-66. 01998 by American Society for Reproductive Medicine.)
Key Words: estradiol,
Norplant, levonorgestrel
cervical
mucus, sperm penetration
For progestin-only contraceptive methods such as Norplant implants (The Population Council, Inc., New York, NY) and progestinonly pills, changes in cervical mucus are considered to be a very important factor in pre-
distance,
contraception,
backup contraception,
progesterone,
venting pregnancy (1). At approximately the ninth day of an ovulatory menstrual cycle, the cervical mucus becomes thin, watery, and receptive to sperm penetration, and the penetrability increases to a peak just before ovulation
(2). With increasing serum progesterone concentrations after ovulation, the cervical mucus becomes scanty, thick, opaque, and unfavorable for sperm penetration, and sperm penetration diminishes. The time and degree of sperm penetrability vary among individuals. Administration of progestinonly contraceptives simulates these naturally occurring effects (3). Few studies have been conducted to evaluate the effect of Norplant implants on cervical mucus. In these studies, cervical mucus from implant users was found to be scanty and viscous even during regular menstrual cycles. In vitro examination showed sperm penetration to be markedly poorer in mucus collected from implant users than in mucus from matched control subjects not using hormonal contraceptives (4). Postcoital tests in another study of Norplant users indicated that few sperm reached the cervital canal, and those that did had reduced motility (5). A third study found that after implant removal, despite the rapid return of ovulation (within 4 weeks for 87% of the women), fertilization may be delayed because the cervical mucus remains poor, as measured by quantity, spinnbarkeit, and ferning (6). With respect to onset of action, Norplant implants are reported to be effective within a few hours of insertion, with blood levels of levonorgestrel being sufficient to prevent conception by 24 hours (7, 8). To date, however, there have been no data published confirming this time sequence. Even though the exact mechanism by which levonorgestrel prevents conception has not been defined completely, the contraceptive action is most probably a combination of at least two effects: suppression of ovulation and thickening of the cervical mucus (7,8). With changes in cervical mucus being an important component of the overall mechanism of action, the rapidity and reliability of these changes have important programmatic implications. Indeed, the protocols that guide clinicians as to when in a menstrual cycle Norplant implants can be inserted and the length of time patients will be required either to abstain or to use backup contraception (e.g., condoms) are based, in great measure, on an understanding of this effect as shown for progestin-only pills and natural progesterone (9, 10). This study was conducted to document better the cervical mucus changes within the first hours to days after Norplant implant insertion and to estimate when the cervical mucus is hostile enough to suggest contraceptive effect. These data should provide scientific evidence on the length of time that backup contraception is needed after insertion, particularly for those women having insertions performed in the late preovulatory or early periovulatory phase. This report represents the first in a series of articles that will report on these cervical mucus changes. FERTILITY & STERILITY@
MATERIALS AND METHODS Study Population Subject enrollment began at two clinical sites, PROFAMILL4 in Santo Domingo, Dominican Republic and the Johns Hopkins Bayview Medical Center in Baltimore, Maryland, in October 1994 and December 1994, respectively. Enrollment was completed at both sites in September 1995 after a total of 42 healthy female volunteers aged 18-40 years were enrolled. All subjects had a normal history and physical examination, had not used hormonal contraception in the 4 months before entering the study and did not have a recent history of pregnancy (<3 months postpartum). Subjects were between days 8 and 13 (inclusive) of their current menstrual cycle on the insertion date and had sufficient cervical mucus for evaluation 22 hours before implant insertion. Finally, the subjects were required to be abstinent for 48 hours before insertion and agreed to abstain from coitus or to use a nonspermicidal condom for the duration of the _ study. After being informed about the purpose of the study and the risks and benefits associated with the use of this contraceptive method, the subjects gave informed consent in accordance with the requirements for this Institutional Review Board-approved protocol. Every woman admitted to the study was specifically advised that the implants could be removed, if she so desired, at any time in the same clinic.
Subject Assessments The subjects made up to seven clinic visits (screening, admission, and 5 follow-up visits). Subjects in Baltimore spent the first 24 hours in the General Clinical Research Center, whereas subjects in the Dominican Republic returned to the clinic at the specified follow-up times during this initial period. Cervical mucus samples were taken for scoring and for in vitro mucus penetration testing, and blood was drawn for evaluation of serum progesterone and estradiol concentrations before insertion. The implants then were inserted using the standard insertion technique. Follow-up visits were held in the clinic at 6, 12, and 24 hours after insertion and on days 3 and 7 after insertion for subsequent cervical mucus sampling and blood sampling (an aliquot also was used for levonorgestrel evaluation after insertion). A subject was considered to have completed the study if she returned to tbe clinic for her day 7 follow-up visit and completed the procedures at this visit.
Cervical Mucus Collection Cervical mucus was collected according to the WHO Laboratory Manual for the Examination of Human Semen and Sperm-Cervical Mucus Interaction (11). A cervical cath-
eter was constructed from polyethylene tubing and attached to a lo-mL syringe. A speculum was inserted into the vagina and the appearance of the cervix and the external OS was 259
examined, along with the amount of mucus present at the OS. The external OS was wiped gently with a moist cotton swab to remove the external pool of vaginal contaminants. With the use of forceps, the catheter tip was inserted l-2 cm into the cervical canal. Once the catheter was positioned, gentle suction was applied with the syringe to aspirate mucus. Once sufficient mucus was aspirated to perform the required tests, the catheter was removed. (If insufficient mucus was present, the tests were not performed, and both the cervical mucus score and the vanguard sperm penetration distance were assigned a “0” value.) The catheter was then disconnected from the syringe and cut into two pieces. The sample of cervical mucus in the piece most distal from the syringe was evaluated. The mucus sample in the remaining catheter (just proximal to the syringe) was prepared for the mucus penetration test, or both ends of this piece of the catheter were sealed with Critoseal (Sherwood Medical Industries, Inc., St. Louis, MO), labeled appropriately, and refrigerated at 4°C for subsequent testing within 5 days of collection.
Evaluation
and Scoring of Cervical Mucus
The cervical mucus was evaluated and scored during collection of the mucus by a single observer at each site. We followed the guidelines of the World Health Organization (11) for evaluating and scoring the mucus, which were, in turn, based on the original system proposed by Insler et al. (12). Variables evaluated included spinnbarkeit, consistency, cellularity, and feming. The volume component was excluded from evaluation in this study, yielding a total score of 12 as opposed to a total score of 15 as per the usual guidelines (11). We excluded the volume measurement because, to determine the actual mucus volume, the entire amount of mucus present would have to be aspirated. Because the rate of mucus production is unknown, we could not be certain whether the amount of mucus produced between the O-hour and 6-hour or the 6-hour and 12-hour time periods would accurately reflect normal mucus production or would be decreased by the action of levonorgestrel. Therefore, we believed that including the volume component would not yield accurate results. The sum of scores for the four variables produced the cervical mucus score, which could range from 0 to 12. For the purposes of this analysis, we chose to group the scores within this range into three categories. A score of O-4 indicated poor mucus conditions; 5-8 was considered fair; and a score of 9-12 was considered good, indicating mucus capable of good sperm penetration. Using the scoring system of the World Health Organization, a score >lO usually indicates good cervical mucus favoring sperm penetration, and a score ~10 may represent unfavorable mucus. Justification for the classification of the World Health Organization as well as that proposed by Insler et al. (12) was not given. We believe that our classification system, although
260
Dunson et al.
Timing of effectiveness
of Norplant implants
subjective, tems.
is sound and compares
In Vitro Mucus Penetration
favorably
with past sys-
Test
In this study, we used a flat capillary tube to contain cervical mucus during testing of sperm penetrability. The tube was 3 mm X 0.3 mm in cross-section and was cut to a length of 2-3 cm. This length is shorter than the common 5-cm length used in most contemporary research studies of mucus (13-17) and the lo-cm length described by the World Health Organization. The reduced length was necessary to accommodate the small specimen volumes of mucus collected in this study. The mucus specimens collected would not have filled longer tubes, and the uncontrolled technical artifacts induced by incomplete filling of tubes with mucus would have obfuscated interpretation of these experiments. In capillary tube tests of sperm penetration, the exposure interval of semen to mucus depends upon tube length. If the interval is too long, sperm will fill the entire tube under conditions of good penetration, and vanguard penetration distance will not be directly measurable. The common exposure interval is 30 minutes at 37°C for a tube 5 cm in length (13-17); for the lo-cm tube, the World Health Organization recommended interval is 60 minutes. In the present study, the exposure time was 30 minutes. Fresh semen was used 51 hour after ejaculation. While the mucus penetration test was being run, a semen analysis was performed to determine the volume of the ejaculate, the concentration of sperm in a sample of uniformly mixed semen, and the percentage of sperm demonstrating motility. Because motility was used to estimate viability (i.e., was not used to determine fertilizing potential), motility was defined as any demonstration of movement, regardless of the presence of forward progression. The percentage of sperm demonstrating progressive forward motility also was determined. Except for the definition for motility, the semen analysis was performed using a Neubauer hemocytometer according to the guidelines of the World Health Organization (11). The mucus penetration test was designed to assess both the penetration distance of the vanguard sperm in the mucus and the overall numbers of penetrating spermatozoa. These two measures of penetration were retained as distinct variables. During performance of the test, the numbers of motile and nonmotile sperm were counted at every 0.5 cm (for a total of up to 5 positions), and the position of the vanguard sperm was noted. Vanguard penetration distance was measured directly for tests in which sperm had not penetrated the entire length of the mucus column. In some cases, sperm penetrated the entire length of the mucus column and we could not be certain how far they would have traveled in a longer mucus column. In this case, vanguard penetration distance was estimated by fitting the counts of sperm numbers versus position along the tube (i.e., distance from the semen-mucus interface) to an exponential
Vol. 69, No. 2, February
1998
function (16, 18). Penetration distance then was defined as the distance from the semen-mucus interface at which the exponential function predicted a count of one sperm; this is analogous to the paradigm used by Aitken et al. (16). Our paradigm thus predicted how far the vanguard sperm would have penetrated if the column of mucus had been much longer (i.e., so that sperm had not traversed the entire length of the mucus column). For this analysis, we chose to use a vanguard sperm penetration distance of < 1 .O cm as a cutpoint for contraceptive effect. A distance of < 1.O cm was chosen because, in all but one subject with poor cervical mucus at baseline, the vanguard sperm penetration at baseline was -=L1.O cm; conversely, no subjects exhibited a good cervical mucus score at baseline when baseline sperm penetration was cl.0 cm. If the sperm penetration scoring system of the World Health Organization had been used, the score for vanguard sperm penetration would be “0” when sperm penetration was c3.0 cm. Given the technical differences in methodology between our system and that of the World Health Organization, we believe that our score is more conservative.
Cervical Mucus Changes Originally, we intended to analyze the changes in cervical mucus by grouping the subjects by cycle day of insertion. However, our results indicated that the chronological day of the cycle did not always correlate with the functional date of the cycle because of individual variations in the length of the follicular phase. Therefore, we considered that the most logical and appropriate way to study the changes in cervical mucus was by grouping the subjects by baseline value of cervical mucus (poor, fair, or good) rather than by chronological date.
Hormone Assays Blood was drawn at various times throughout the study for hormonal assays. The methods and results of these assays and their relation to cervical mucus and ovarian function will be detailed in subsequent articles in this series.
RESULTS Most women (54.8%) in this study had the implants inserted on days 12 and 13 of their menstrual cycle (data not shown). Originally, recruitment efforts were focused on evenly distributing volunteers along the 5 days of study (e.g., 10 subjects admitted on day 8, 10 subjects on day 9, and so on). However, it soon became apparent that few of the women had evaluable cervical mucus on day 8. Thus, the distribution of subjects by day of the menstrual cycle was uneven. The mean age of the study subjects was 23.8 years and the average weight was 57.9 kg. Table 1 shows the cervical mucus scores found before Norplant implant insertion, classified according to day of the cycle and stratified by quality at baseline as poor (O-4), fair
FERTILITY
& STERILITY@
Percentage of women in each baseline cervical mucus group stratified by cycle day. Cycle day Baseline cervical mucus group Poor (o-4) Fair (5-8) Good (9-12)
8/9 (n = 6)
10/l 1 (n = 13)
12/13 (n = 23)
61 33 0
23 23 54
26 39 35
Note. Data are given as percentages.
(5-8), and good (9-12). As expected, most mucus samples on days 8 and 9 were poor (67%), and none had a good score. The cervical mucus samples collected between days 10 and 11 and 12 and 13 were somewhat more uniform, with 77% and 74%, respectively, exhibiting fair or good quality. On days 10 to 11, 54% of the cervical mucus samples were scored as good, compared with 35% of those samples taken on days 12 to 13. When the median cervical mucus scores were observed over time and stratified by quality of the mucus at baseline (Fig. l), subjects with good cervical mucus at baseline exhibited a median score at baseline of 10, which decreased to 6 (fair mucus) by 24 hours and to 3.5 (poor mucus) by day 3. It was noteworthy that subjects with poor mucus at baseline experienced a rise in mucus quality during the 1Zhour period after insertion; however, a change back to poor mucus was observed by 24 hours. The overall median cervical mucus score seen at baseline was 6 (of a possible total score of 12) indicating that, for at least these subjective observations, the mucus was somewhat hostile before insertion of Norplant (data not shown). This overall score declined to 5 at 12 and 24 hours and continued to decrease through day 7 to 2, a score that is judged as hostile to sperm penetration using the standard criteria of the World Health Organization. Most subjects (>70%) demonstrated mucus of poor quality (O-4) by day 3 of the study, regardless of the quality of their mucus at baseline (Table 2). Of those subjects who exhibited fair mucus at baseline, 71% exhibited poor mucus by day 3 and 100% by 7 days after insertion. Collectively, by day 3, 73% of the subjects had a poor cervical mucus score and by day 7,90% exhibited mucus of poor quality; only one subject on either of these days exhibited a good score. As shown in Figure 2, there was a substantial drop in the overall median distance traveled by the vanguard sperm (in centimeters) after 12 hours for each cervical mucus score grouping. There was an increase in the median distance traveled between baseline and 6 hours for each grouping, and it continued to increase through 12 hours for those subjects with poor mucus at baseline. The median distance traveled decreased rapidly between 12 and 24 hours to CO.5 cm in
261
Median cervical mucus scores by cervical mucus score at baseline at each time point.
-o-
Poor cervical mucus at baseline (O-4)
t
Fair cervical mucus at baseline (5-8)
-Good
0
I I
I I
0612
I I
I I
24
3
Hour
cervical mucus at baseline (9-12)
I 7
Day
Day
Follow-up
subjects with fair and poor mucus, and to 1.0 cm in those with mucus considered to be good. The distance traveled decreased or remained consistently suppressed for all groups until reaching a median distance of 0 by day 7. As expected, the initial distance traveled by the vanguard sperm was greater for those subjects with good mucus and was less for the other two groups.
Period
Table 2 also shows the percentage of subjects demonstrating poor vanguard sperm penetration at different time points stratified by the cervical mucus score at insertion. Poor sperm penetration was defined as any penetration of < 1.0 cm. Consistent with the findings for cervical mucus scores, the percentage of subjects with poor vanguard sperm penetration decreased through 12 hours, with the exception of
Percentage of women achieving poor cervical mucus and poor sperm penetration stratified by baseline cervical mucus group at each time point. Time point Baseline cervical mucus group
Oh
No. of women with poor cervical mucus/no. women studied (%) Poor (O-4) Fair (5-8) Good (9-12) Overall No. of women with poor sperm penetration (Cl.0 cm)/no. of women studied (%) Poor (OA) Fair (5-8) Good (9-12) Overall
6h
12 h
24 h
Day 3
Day I
of 13/13 o/14 o/15 13/42
(100) (0) (0) (31)
Ill 3 o/14 l/15 8/42
(54) (0) (7) (19)
6113 4114 2/14 12/41
(46) (29) (14) (29)
9112 3114 3/15 15/41
(75) (21) (20) (37)
10/13 10/14 10/14 30/41
(77) (71) (71) (73)
10/13 14/14 14/15 38/42
(77) (100) (93) (90)
12/13 6114 o/15 18/42
(92) (43) (0) (43)
9113 3114 l/14 13/41
(69) (21) (7) (32)
7/l 1 (64) 4114 (29) 1114 (7) 12I39 (31)
1 l/12 10/13 6115 27140
(92) (77) (40) (68)
900 11111 12/14 32/35
(90) (100) (86) (91)
lo/12 13/14 14/14 37/40
(83) (93) (100) (93)
Note. The denominators for the sperm penetration test and mucus sample may differ because the sperm penetration adequately or the mucus sample was contaminated or was not collected within the specified time limits.
distance
262
Vol. 69, No. 2, February 1998
Dunson et al.
Timing
of effectiveness
of Norplant
implants
could not be determined
Median vanguard sperm distance by cervical mucus score at baseline at each time point.
+-Good
0612
24 Hour
3
7
Day
Day
Follow-up
those subjects with good cervical mucus at baseline; an increase was observed for these subjects. The percentage of subjects with poor penetration increased between 12 and 24 hours after insertion and remained high through day 7. Subjects with good mucus quality at baseline demonstrated increasingly poor penetration at all observation points. Overall, at day 3, 32 of 35 women (91%) had poor penetration, and at day 7, 37 of 40 (93%) had poor sperm penetration. Because all of the variables examined in this study are subject to individual variation, we reviewed the results by individual, particularly for day 3 and day 7; a description of some of these data follows. One subject’s mucus, which was poor at baseline, improved to good (9) by day 3 with a vanguard sperm penetration of 1.0 cm; however, by day 7, there was insufficient mucus to analyze the sample. Another subject, whose mucus quality was poor at baseline, exhibited good mucus at day 7 with a vanguard sperm penetration of 2.5 cm. However, the results at this time point are questionable, given that all prior mucus scores were poor or fair (highest = 8) and the vanguard sperm penetration was 5 1.O cm. In addition, hormone levels for this subject were consistent with contraceptive effect at each time point evaluated. In addition, we further examined individual data for subjects who exhibited good cervical mucus quality at any
FERTILITY
& STERILITY@
cervical mucus at baseline (9-12)
Period
time point during the study. Eleven of 15 subjects who exhibited good cervical mucus at baseline demonstrated poor mucus by day 3; the four exceptions scored as fair (5-6). All but one subject whose mucus was good at baseline were scored as poor by day 7; the exception was scored as fair (5). No subjects who had good cervical mucus had poor sperm penetration (< 1.O cm) at any time point. Finally, we examined individuals who had both a good cervical mucus score and a sperm penetration other than poor (2 1.0 cm) at any time point. Although there were several subjects who matched these criteria at 0 and 6 hours, we found only two subjects who fulfilled these criteria at 24 hours, and one each at days 3 and 7. The subjects at days 3 and 7 were the same individuals discussed previously. Although detailed changes in serum hormone levels will be reported in a subsequent article, we observed that deterioration of cervical mucus and sperm penetration occurred uniformly in all subjects regardless of their hormonal status (i.e., some women ovulated after insertion, as judged by increased progesterone levels, whereas some had high preovulatory estradiol levels without an elevation in progesterone).
263
Percentage
distribution
of vanguard
sperm penetration
at each time point and long-term
use results.
Time point
Penetration
distance (cm)
Insufficient SO.05
mucus
0.6-1.0 1.1-1.5 1A-2.0 >2.0
6h
12 h
24 h
Day 3
Day 7
Long term*
(n “=“,2)
(n = 41)
(n = 39)
(n = 40)
(n = 3.5)
(n = 40)
(n = 16)
0 43
0 22
0 15
3 63
9 80
28 65
31 44
I 5 10 36
20 7 20 32
28 21 10 26
13 10 8 5
9 3 0 0
0 5 0 3
12 6 6 0
No&. Missing values resulted when the sperm penetration not collected within the specified time limits. * Data for long-term use were abstracted (4).
distance could not be determined
DISCUSSION Norplant implants have now been approved and available in the United States for >6 years and for a longer period in other countries. During this time, a variety of guidelines have been proposed that assist clinicians in determining when in a menstrual cycle Norplant implants can be inserted and to what extent a backup method (e.g., condoms) may be required (19,20). Experts developing these guidelines have based their recommendations, in part, on an understanding of the hypothesis that, when exposed to progestin, the cervical mucus changes rapidly and consistently enough to form a sperm block within a few hours to a few days after insertion. However, because few studies have attempted to examine this effect rigorously, clinical decisions regarding insertion timing and the need or duration for a backup method when insertions occur after day 7 of the menstrual cycle have been based largely on supposition and personal interpretations of what few data are available. Data presented in this report support the finding that progestin-only contraceptives cause profound alterations in the properties of human cervical mucus and, in the case of Norplant implants, interfere with the migration of sperm through the mucus. The physical properties of cervical mucus (e.g., spinnbarkeit, ferning) that are important in the sperm-cervical mucus interaction have been shown to be influenced adversely by progestational agents (21-24). We observed similar effects in this study, as all cervical mucus parameters indicated a hostile cervical mucus soon after insertion of Norplant implants. Overall, mucus quality deteriorated rapidly after 24 hours and could be considered hostile to sperm penetration by day 3. In a normally ovulating woman, the cervical mucus generally remains hostile until day 8 or 9 of the menstrual cycle (25). Our results indicated this to be true, as most samples collected on these days were judged to be of poor quality. Furthermore, mucus quality deteriorated over time in most subjects regardless of which day of the cycle insertion occurred.
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adequately
or when the mucus sample was contaminated
or was
Sperm penetration was inhibited in most subjects by 24 hours. Similar results have been reported previously for other progestin-only methods (26-29). Our data show that vanguard sperm penetration decreased rapidly between 12 and 24 hours, particularly in those subjects with good and fair mucus quality at baseline. We observed an increase in the median distance traveled between baseline and 6 hours for all cervical mucus groups at baseline and through 12 hours for those subjects with poor mucus at baseline; however, we have no explanation for this finding. After 24 hours, sperm penetration either remained suppressed or continued to decrease throughout the study, with 91% of the subjects demonstrating a sperm penetration of < 1.O cm by day 3 and 93% by day 7, a result that suggests impaired fertility. In a recent study, Barbosa et al. (30) observed the relation between Uniplant insertion and changes in cervical mucus. The progestin in this implant was observed to affect cervical mucus production and sperm penetration 24 hours after implant insertion in 71% of the women studied; mucus production and sperm penetration were affected in all women by 48 hours. The results we obtained at day 3 after insertion are very similar to those reported in a study of long-term Norplant implant users, in which a reduction in the amount of cervical mucus and impairment of sperm penetration were found regardless of the length of use, day of cycle, or endocrine pattern at the time of sampling (4). Table 3 illustrates that, in the study of long-term users, none of the subjects had a vanguard sperm penetration distance >2 cm, whereas 12% had a vanguard sperm penetration distance > 1.0 cm but 52.0 cm. None of the subjects in our study had sperm penetration >2 cm, and only 3% had a penetration distance Cl.0 cm but 52.0 cm at day 3 after insertion. Thus, by day 3, the deterioration in cervical mucus is similar to what is attained during long-term use. Given that a high percentage of women ovulate during long-term use of Norplant implants despite a high level of
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effectiveness, we can infer that we may have comparable contraceptive effectiveness by day 3 of use. However, we should note that other subtle endocrine changes have been reported in ovulatory cycles during long-term use, such as blunted LH peaks and diminished progesterone levels, which also may contribute to the contraceptive effect (31). We cannot be certain that these changes occur when the development of the follicle has taken place without the continuous influence of levonorgestrel, and the implants are inserted late in the follicular phase. However, in a recent study in which the implants were inserted in the preovulatory phase, the LH surge in that cycle was also blunted, as has been reported in long-term use (32). Overall, our data are comparable to the findings of Petta et al. (33), who used the same study design in Depo-Provera users. Although similar results are described, their findings suggest that contraceptive effect may not be established fully in Depo-Provera users until day 3 after injection. This conclusion is based on the fact that one subject at day 3 was observed to have mucus of good quality, a vanguard sperm penetration of 2.5 cm, and a high motile sperm count. Although by day 7, all parameters were negative, these authors chose a very conservative approach on the basis of this subject’s findings at day 3. The current study was conducted to explore objectively the nature of the relation between Norplant implant insertion and cervical mucus changes and to provide clinicians with objective data for use in clinical decision making. As a result, clinicians should be more confident with, and clients might have more convenient access to, this contraceptive. These data provide policy makers, clinic managers, and clinicians with important information about how they can improve client access to Norplant implants. Our data indicate that backup protection for the entire cycle is not necessary given the profound effect of levonorgestrel on the cervical mucus shortly after insertion, even in the event of possible ovulation. Although there are no clear absolute values for cervical mucus changes or sperm penetration that can be correlated directly to contraceptive effectiveness, our data indicate deterioration in the quality of cervical mucus and sperm penetration by 24 hours after insertion, and this deterioration was severe enough by 72 hours after insertion to suggest impaired fertility indicative of contraceptive effectiveness. Therefore, we conclude that backup methods of contraception such as condoms need not be used for >3 days after insertion, even when the implants are inserted close to ovulation.
Acknowledgmenrs: Partial support for this work was provided by Family Health International with funds from the U.S. Agency of International Development (USAID), although the views expressed in this article do not
FERTILITY
& STERILITY@
necessarily reflect those of USAID. Family Health International is an international nonprofit organization that conducts research and provides technical assistance in reproductive health, family planning, sexually transmitted diseases, and AIDS. It is based in Research Triangle Park, North Carolina. We extend a special note of appreciation to Noel McIntosh, who provided ideas that were germinal to this project.
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