- Email: [email protected]
Self-Testing for Pregnancy Among Women at Risk
Self-Testing for Pregnancy Among Women at Risk A Randomized Controlled Trial Mary D. Nettleman, MD, MS, Jennifer R. Brewer, BA, Adejoke B. Ayoola, RN, PhD Background: The timing of pregnancy recognition affects early pregnancy and the timing of prenatal care. Little research has been done on how to make women at risk more alert to the possibility of pregnancy. Design:
The study was an RCT performed and analyzed between 2006 and 2007.
Setting/ Participants were low-income, adult women who were having unprotected intercourse and participants: were not actively trying to conceive. Intervention: Women in the intervention group received a free home-pregnancy test kit and were able to order more kits as needed. Six-month follow-up information was obtained. Main outcome measures:
The main outcome measures were suspicion and testing for pregnancy.
Results:
Ninety-one percent of the 198 participants completed the study. Women in the intervention group suspected pregnancy 2.3 times during the 6-month period compared to 1.2 times for women in the control group (p⬍0.0001). Women in the intervention group tested for pregnancy 93% of the time when they suspected pregnancy. Women in the control group tested for pregnancy only 64% of the time when they suspected pregnancy (p⬍0.0001).
Conclusions: Women who were having unprotected intercourse were more likely to suspect and test for pregnancy if they were supplied with a free home-pregnancy test kit. Trial registration:
NCT00390754 (Am J Prev Med 2009;36(2):150 –153) © 2009 American Journal of Preventive Medicine
Introduction
Q
ualitative research has shown pregnancy recognition to be a multi-step process. The first step in the process is being alert to the possibility of pregnancy.1 Alert in this sense means having a low threshold of suspicion for pregnancy and testing when suspicion occurs. No intervention has been shown to affect alertness to potential pregnancy. However, some studies have shown that the availability of a home test lowers the threshold of suspicion and testing for sexually transmitted diseases.2,3 Increased alertness to potential pregnancy has public health implications because it may be associated with earlier recognition of pregnancy. For example, women who are trying to get pregnant recognize their preg-
From the Department of Medicine (Nettleman), College of Human Medicine, and the Department of Anthropology (Brewer), College of Social Science, Michigan State University, East Lansing, Michigan; and the Department of Nursing, Calvin College (Ayoola), Grand Rapids, Michigan Address correspondence and reprint requests to: Mary D. Nettleman, MD, MS, B 427 Clinical Center, Michigan State University, East Lansing MI 48823. E-mail: [email protected].
150
nancies earlier than those who are not trying to conceive.4 Early recognition of pregnancy is beneficial because women who do not realize they are pregnant may continue risk behaviors or take medications that will adversely affect fetal development.5– 8 Delayed recognition is a primary cause of late entry into prenatal care.9 For these reasons, increased alertness is desirable among women at risk for pregnancy. An RCT was performed to determine if having a home-pregnancy test on hand would cause women to have a lower threshold of suspicion for pregnancy and to test more frequently if pregnancy was suspected. The study was confined to adult women who were having unprotected sex and were not actively trying to conceive.4 The primary outcome was alertness, defined as the number of times a woman suspected and tested for pregnancy during the study period.
Methods Participants To be eligible, participants were required to be aged 18 –34 years, sexually active, not pregnant, not desiring pregnancy,
Am J Prev Med 2009;36(2) © 2009 American Journal of Preventive Medicine • Published by Elsevier Inc.
0749-3797/09/$–see front matter doi:10.1016/j.amepre.2008.09.023
and not surgically sterile. Participants had to have had intercourse at least once in the previous 6 months without using effective contraception (hormonal or barrier methods or male vasectomy). The population was confined to women who were currently on Medicaid, had a child on Medicaid, or whose last pregnancy was funded by Medicaid. This was a requirement of the Michigan Department of Community Health, which provided funding, so that the results could inform decisions by the Medicaid program they administered. Eligibility criteria were confirmed during the telephone enrollment and again by analyzing the results of the baseline survey. The protocol was reviewed and approved by the Michigan State University IRB. All participants gave written, informed consent. The study was registered with ClinicalTrials.gov prior to opening enrollment.
The surveys asked about sexual activity, use of pregnancy tests, menstrual history, and whether the participant suspected pregnancy at any time during the preceding 3 months. Survey questions were pilot-tested for face validity. For the outcome questions, the reported frequency of suspicion/ testing was compared with answers to a question that asked whether suspicion or testing ever occurred. Concordance of 96.5% and 99.4% was found for the suspicion and testing questions, respectively. If the response to an outcome question was unclear, women were contacted for clarification. Whenever possible, questions from national surveys were used,10 which provided the dual advantage of allowing direct comparison with national data and using questions that have been tested in large populations.
Recruitment
Home-Pregnancy Test
A commercial mailing list was obtained from a marketing company. The list was restricted to households headed by single Michigan women aged 18 –34 years with household incomes ⬍$20,000. A total of 25,370 addresses were identified in the database that met these criteria. Flyers describing the study were mailed to a sample of 10,000 women randomly drawn from this list (see Sample Size section below). Interested women called an automated telephone line and answered eligibility questions. Women who were eligible heard a description of the study. Those interested left their contact information and were mailed a packet including the first survey and the informed consent document. Women who returned these items and whose responses confirmed eligibility were enrolled in the study. Survey enrollment was closed when it was estimated that a sufficient number of packets had been mailed to meet the sample size requirements (approximately 3 weeks after the flyer was mailed). The study began enrolling participants in November 2006.
Study Groups and Measurements Group assignment was determined by randomly numbered, sealed envelopes controlled by a third party who was unconnected to the study and did not have access to study data. Except for the study condition (free pregnancy test kits were given to the intervention group), the two groups received identical information and mailings. Women in both groups completed a baseline survey at the time of enrollment and received a letter encouraging early pregnancy recognition and describing how to use a home-pregnancy test kit. Women in both groups also received an educational brochure discussing the importance of pregnancy planning, use of contraception until pregnancy was desired, and preconceptual health. Women in the intervention group received a home-pregnancy test kit by mail and an order form allowing them to order replacement kits as needed. Two identical, additional surveys were mailed to each group at 3-month intervals, with the last survey received by August 2007. Participation was voluntary; women in both groups were free to change their behaviors and test for pregnancy as they wished. Continued participation was not contingent on any behaviors or testing patterns for women in either group.
February 2009
Survey Questions
The First Response Early Result® kit was used in the study.11 Kits were purchased from retail sources and contained three test strips per kit, as well as directions for use.
Sample Size The total sample size was calculated to be approximately 200, based on an 80% power to detect a doubling of homepregnancy test use. Estimated baseline utilization was 20% for the 6 months, and it was estimated that 10% would drop out. The size of the mailing was determined from national data and pilot studies. Of 100 women aged 18 –30, the National Survey on Family Growth12 results showed that 5% were not using any hormonal or barrier methods of contraception and were nonsterile, sexually active, and not pregnant. Additional women might be using contraception inconsistently. However, eligibility criteria also included being from a Medicaid population, which decreased the number of eligible women. Although electronic mailing lists are updated monthly, inaccurate addresses sometimes occur as a result of imperfect listings and from participants moving/changing addresses. Based on this information and previous experience from pilot studies, it was anticipated that 2% of mailings would be read by an eligible woman who was interested in the study and would enroll.
Statistical Analysis The primary outcomes were number of times pregnancy was suspected per woman and the proportion of episodes of suspected pregnancy that resulted in pregnancy testing. For the latter, women were asked if they suspected pregnancy zero, one, two, or three times in a 3-month period. Differences in categoric data were evaluated using Fisher’s test and the chi-square test. Differences in continuous data were evaluated using the unpaired t test. All p values were twosided. The analysis was completed in 2007.
Results There were 198 women enrolled in the study, and 99 were randomly assigned to each group. Baseline characteristics were similar for the two groups (Table 1). All women met the eligibility guidelines described above. A total of 181 women (91%) completed both Am J Prev Med 2009;36(2)
151
Table 1. Baseline characteristics (% unless otherwise noted) Intervention Control p (nⴝ99) (nⴝ99) value Median age (years) White race ⬍High school education Daily vitamin user Marijuana use, past 3 months Hypertension Current smoker Binge drinkera at least monthly Used a home-pregnancy test in past year ⱖTwo partners in past 6 months Periods are usually regular Had no late or missed periods in past 6 months
24 71 11 27 15 18 54 13
24 75 14 35 17 16 56 13
1.00 0.63 0.67 0.28 0.84 0.85 0.89 1.00
59
60
0.99
71
73
0.87
82 57
84 51
0.85 0.48
Binge drinking defined as ⬎6 drinks on one occasion
a
surveys; 87 of these were assigned to the intervention group and 94 to the control group (Figure 1). The remaining women did not return one or both surveys and were unable to be contacted by telephone or mail (16 women), or did not follow the protocol (1 woman). There was no difference in age, race, education, smoking, or drinking between women who did not complete both surveys and those who did complete both surveys. Women were asked how many times they suspected that they might be pregnant during the study period. Four women in the control group and four women in the intervention group did not answer this question on at least one of the two surveys. Among those responding to the question, women in the intervention group suspected that they might be pregnant almost twice as often as women in the control group (2.3 times per woman over 6 months compared to 1.2 times, p⬍0.0001). Once pregnancy was suspected, women in the intervention group were more likely to have a pregnancy test (either at home or in a clinic) than women in the control group (93% of the time versus 64% of the time, p⬍0.0001). Among women who were tested, 100% in the intervention group used at least one home-pregnancy test during the episode compared to 85% in the control group. Women in the intervention group were able to request additional test kits as needed from the research team. Seventy-four percent of women in the intervention group requested at least one additional homepregnancy test. Participants received an average of 2.4 test kits per woman over the study period, including the test kit they received upon entering the study. Overall, 69 women (79%) in the intervention group used at least one pregnancy test compared with 51 (54%) in the control group (p⬍0.001). If women who 152
dropped out of the study were conservatively assumed not to have tested, the difference remained statistically significant (p⫽0.01). Women were asked to give the reasons for pregnancy testing (multiple responses were allowed). Among women who tested, the most common reason for testing was a late period, cited by 71% in the intervention group and 70% in the control group. In each group, 99% said they had no trouble following the directions on the box.
Summary Women were more alert to potential pregnancy and more likely to test for pregnancy if they were supplied with free home-pregnancy test kits. This is the first study to identify an intervention that successfully addresses alertness to pregnancy. Increased alertness is potentially important because it may be associated with earlier recognition of pregnancy. Indirect evidence4 indicates that women who would be expected to be more alert to pregnancy (those actively trying to conceive) recognize pregnancies earlier than those who would be expected to be less alert to pregnancy (those not trying to conceive). Women in the intervention group tested more often when they suspected pregnancy. The acceptability of testing in the intervention group may have been increased by being able to use a test in the privacy of the home13 and by the knowledge that additional free tests were available. Alternatively, the presence of the test kit might have served as a reminder or motivator, resulting women having a lower threshold of suspicion when a period was late. The study used a relatively novel recruitment strategy, based on a purchased mailing list, that was quite successful. Commercial marketing lists are drawn from
Figure 1. Enrollment
American Journal of Preventive Medicine, Volume 36, Number 2
www.ajpm-online.net
numerous data sources, are relatively inexpensive, and can be tailored to some extent. Using a random sample from all available addresses, the study was able to recruit a fully eligible population in a fraction of the time that would have been required had recruitment been solicited through clinic-based settings. The study is subject to several limitations. The population was restricted to low-income, adult women having unprotected intercourse and is not representative of all women in the country. All women in the study were literate and able to speak and read English. Women who choose to participate in a study may be different from those who refrain (selection bias), which affects the generalizability of all studies involving human subjects. However, women who chose to enroll were randomly assigned to the intervention or control group, which makes it highly unlikely that selection bias had an influence on the results within the study population. The study relied on self-reported use of pregnancy tests and suspicion of pregnancy by women in both the control and intervention groups. Thus, it is subject to reporting and recall biases. There is no gold standard to apply in this case to determine if a woman was accurate in reporting that she suspected pregnancy. However, suspecting and testing for pregnancy are not trivial events and are unlikely to be forgotten in a 3-month period. Also, the number of reported cases of pregnancy testing correlated almost exactly with the number of pregnancy tests used in the intervention group. Women in the control group tested more frequently than would have been expected from the baseline survey. There are several possible explanations for this. Filling out surveys and receiving educational material may themselves influence behavior by increasing awareness or suspicion. However, the surveys and educational material were given to both control and intervention women. Thus, the effect would be evenly distributed and would cause an underestimation of the effect of the test kit itself. Such an observational bias would strengthen the results with respect to home-pregnancy test kits. There are some theoretical drawbacks to distributing home test kits. Cost is a factor in any distribution program. However, home-pregnancy test kits are available for less than $1 per test when purchased in bulk, making it financially feasible for Medicaid programs or selected clinics to distribute kits to women at risk. More-frequent pregnancy testing may result in discovery of nonviable pregnancies that would otherwise have remained undetected. This may cause emotional distress. Women may not understand how to use the test and may rely on false results. In the study, all women were able to answer questions about how and when to
February 2009
use the test. Finally, women who wait to be tested in an obstetric clinic may receive prenatal counseling immediately, whereas women who test at home would have to make an appointment. However, many women get tested in urgent care clinics, emergency rooms, or primary care offices that do not provide prenatal counseling. In summary, women in the study population who were supplied with free home-pregnancy test kits were more alert to the potential for pregnancy and more likely to test for pregnancy. Further studies are needed to determine if increased awareness is associated with earlier recognition in women who become pregnant and, ultimately, whether this improves fetal and maternal outcomes. This study was funded by a grant from the Michigan Department of Community Health. No financial disclosures were reported by the authors of this paper.
References 1. Peacock NR, Kelley MA, Carpenter C, et al. Pregnancy discovery and acceptance among low-income primiparous women: a multicultural exploration. Matern Child Health J 2001;5:109 –18. 2. Cook RL, Ostergaard L, Hillier SL, et al. Home screening for sexually transmitted diseases in high-risk young women: randomised controlled trial. Sex Transm Infect 2007;83:286 –91. 3. Phillips KA, Maddala T, Johnson FR. Measuring preferences for health care interventions using conjoint analysis: an application to HIV testing. Health Serv Res 2002;37:1681–705. 4. Kost K, Landry DJ, Darroch JE. Predicting maternal behaviors during pregnancy: does intention status matter? Fam Plann Perspect 1998;30: 79 – 88. 5. Ockene J, Ma Y, Zapka J, Pbert L, Valentine Goins K, Stoddard A. Spontaneous cessation of smoking and alcohol use among low-income pregnant women. Am J Prev Med 2002;23:150 –9. 6. Johnson SF, McCarter RJ, Ferencz C. Changes in alcohol, cigarette, and recreational drug use during pregnancy: implications for intervention. Am J Epidemiol 1987;126:695–702. 7. Hellerstedt W, Pirie P, Lando H, et al. Differences in preconceptional and prenatal behaviors in women with intended and unintended pregnancies. Am J Public Health 1998;88:663– 6. 8. Johnson SF, McCarter RJ, Ferencz C. Changes in alcohol, cigarette, and recreational drug use during pregnancy: implications for intervention. Am J Epidemiol 1987;126:695–702. 9. CDC. Entry into prenatal care—United States, 1989 –1997. MMWR 2000; 48:393– 8. 10. Williams L, Morrow B, Shulman H, Stephens R, D’Angelo D, Fowler CI.PRAMS 2002 surveillance report. Atlanta GA: Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, CDC, 2006. 11. Cole LA, Khanlian SA, Sutton JM, Davies S, Rayburn WF. Accuracy of home pregnancy tests at the time of missed menses. Am J Obstet Gynecol 2004;190:100 –5. 12. Public Health Service. Fertility, family planning, and reproductive health of U.S. women: data from the 2002 National Survey of Family Growth. Series 23, No. 25. 13. Rockett JC, Buck GM, Lynch CD, Perreault SD. The value of home-based collection of biospecimens in reproductive epidemiology. Environ Health Perspect 2004;112:94 –104.
Am J Prev Med 2009;36(2)
153
The study was an RCT performed and analyzed between 2006 and 2007.
Setting/ Participants were low-income, adult women who were having unprotected intercourse and participants: were not actively trying to conceive. Intervention: Women in the intervention group received a free home-pregnancy test kit and were able to order more kits as needed. Six-month follow-up information was obtained. Main outcome measures:
The main outcome measures were suspicion and testing for pregnancy.
Results:
Ninety-one percent of the 198 participants completed the study. Women in the intervention group suspected pregnancy 2.3 times during the 6-month period compared to 1.2 times for women in the control group (p⬍0.0001). Women in the intervention group tested for pregnancy 93% of the time when they suspected pregnancy. Women in the control group tested for pregnancy only 64% of the time when they suspected pregnancy (p⬍0.0001).
Conclusions: Women who were having unprotected intercourse were more likely to suspect and test for pregnancy if they were supplied with a free home-pregnancy test kit. Trial registration:
NCT00390754 (Am J Prev Med 2009;36(2):150 –153) © 2009 American Journal of Preventive Medicine
Introduction
Q
ualitative research has shown pregnancy recognition to be a multi-step process. The first step in the process is being alert to the possibility of pregnancy.1 Alert in this sense means having a low threshold of suspicion for pregnancy and testing when suspicion occurs. No intervention has been shown to affect alertness to potential pregnancy. However, some studies have shown that the availability of a home test lowers the threshold of suspicion and testing for sexually transmitted diseases.2,3 Increased alertness to potential pregnancy has public health implications because it may be associated with earlier recognition of pregnancy. For example, women who are trying to get pregnant recognize their preg-
From the Department of Medicine (Nettleman), College of Human Medicine, and the Department of Anthropology (Brewer), College of Social Science, Michigan State University, East Lansing, Michigan; and the Department of Nursing, Calvin College (Ayoola), Grand Rapids, Michigan Address correspondence and reprint requests to: Mary D. Nettleman, MD, MS, B 427 Clinical Center, Michigan State University, East Lansing MI 48823. E-mail: [email protected].
150
nancies earlier than those who are not trying to conceive.4 Early recognition of pregnancy is beneficial because women who do not realize they are pregnant may continue risk behaviors or take medications that will adversely affect fetal development.5– 8 Delayed recognition is a primary cause of late entry into prenatal care.9 For these reasons, increased alertness is desirable among women at risk for pregnancy. An RCT was performed to determine if having a home-pregnancy test on hand would cause women to have a lower threshold of suspicion for pregnancy and to test more frequently if pregnancy was suspected. The study was confined to adult women who were having unprotected sex and were not actively trying to conceive.4 The primary outcome was alertness, defined as the number of times a woman suspected and tested for pregnancy during the study period.
Methods Participants To be eligible, participants were required to be aged 18 –34 years, sexually active, not pregnant, not desiring pregnancy,
Am J Prev Med 2009;36(2) © 2009 American Journal of Preventive Medicine • Published by Elsevier Inc.
0749-3797/09/$–see front matter doi:10.1016/j.amepre.2008.09.023
and not surgically sterile. Participants had to have had intercourse at least once in the previous 6 months without using effective contraception (hormonal or barrier methods or male vasectomy). The population was confined to women who were currently on Medicaid, had a child on Medicaid, or whose last pregnancy was funded by Medicaid. This was a requirement of the Michigan Department of Community Health, which provided funding, so that the results could inform decisions by the Medicaid program they administered. Eligibility criteria were confirmed during the telephone enrollment and again by analyzing the results of the baseline survey. The protocol was reviewed and approved by the Michigan State University IRB. All participants gave written, informed consent. The study was registered with ClinicalTrials.gov prior to opening enrollment.
The surveys asked about sexual activity, use of pregnancy tests, menstrual history, and whether the participant suspected pregnancy at any time during the preceding 3 months. Survey questions were pilot-tested for face validity. For the outcome questions, the reported frequency of suspicion/ testing was compared with answers to a question that asked whether suspicion or testing ever occurred. Concordance of 96.5% and 99.4% was found for the suspicion and testing questions, respectively. If the response to an outcome question was unclear, women were contacted for clarification. Whenever possible, questions from national surveys were used,10 which provided the dual advantage of allowing direct comparison with national data and using questions that have been tested in large populations.
Recruitment
Home-Pregnancy Test
A commercial mailing list was obtained from a marketing company. The list was restricted to households headed by single Michigan women aged 18 –34 years with household incomes ⬍$20,000. A total of 25,370 addresses were identified in the database that met these criteria. Flyers describing the study were mailed to a sample of 10,000 women randomly drawn from this list (see Sample Size section below). Interested women called an automated telephone line and answered eligibility questions. Women who were eligible heard a description of the study. Those interested left their contact information and were mailed a packet including the first survey and the informed consent document. Women who returned these items and whose responses confirmed eligibility were enrolled in the study. Survey enrollment was closed when it was estimated that a sufficient number of packets had been mailed to meet the sample size requirements (approximately 3 weeks after the flyer was mailed). The study began enrolling participants in November 2006.
Study Groups and Measurements Group assignment was determined by randomly numbered, sealed envelopes controlled by a third party who was unconnected to the study and did not have access to study data. Except for the study condition (free pregnancy test kits were given to the intervention group), the two groups received identical information and mailings. Women in both groups completed a baseline survey at the time of enrollment and received a letter encouraging early pregnancy recognition and describing how to use a home-pregnancy test kit. Women in both groups also received an educational brochure discussing the importance of pregnancy planning, use of contraception until pregnancy was desired, and preconceptual health. Women in the intervention group received a home-pregnancy test kit by mail and an order form allowing them to order replacement kits as needed. Two identical, additional surveys were mailed to each group at 3-month intervals, with the last survey received by August 2007. Participation was voluntary; women in both groups were free to change their behaviors and test for pregnancy as they wished. Continued participation was not contingent on any behaviors or testing patterns for women in either group.
February 2009
Survey Questions
The First Response Early Result® kit was used in the study.11 Kits were purchased from retail sources and contained three test strips per kit, as well as directions for use.
Sample Size The total sample size was calculated to be approximately 200, based on an 80% power to detect a doubling of homepregnancy test use. Estimated baseline utilization was 20% for the 6 months, and it was estimated that 10% would drop out. The size of the mailing was determined from national data and pilot studies. Of 100 women aged 18 –30, the National Survey on Family Growth12 results showed that 5% were not using any hormonal or barrier methods of contraception and were nonsterile, sexually active, and not pregnant. Additional women might be using contraception inconsistently. However, eligibility criteria also included being from a Medicaid population, which decreased the number of eligible women. Although electronic mailing lists are updated monthly, inaccurate addresses sometimes occur as a result of imperfect listings and from participants moving/changing addresses. Based on this information and previous experience from pilot studies, it was anticipated that 2% of mailings would be read by an eligible woman who was interested in the study and would enroll.
Statistical Analysis The primary outcomes were number of times pregnancy was suspected per woman and the proportion of episodes of suspected pregnancy that resulted in pregnancy testing. For the latter, women were asked if they suspected pregnancy zero, one, two, or three times in a 3-month period. Differences in categoric data were evaluated using Fisher’s test and the chi-square test. Differences in continuous data were evaluated using the unpaired t test. All p values were twosided. The analysis was completed in 2007.
Results There were 198 women enrolled in the study, and 99 were randomly assigned to each group. Baseline characteristics were similar for the two groups (Table 1). All women met the eligibility guidelines described above. A total of 181 women (91%) completed both Am J Prev Med 2009;36(2)
151
Table 1. Baseline characteristics (% unless otherwise noted) Intervention Control p (nⴝ99) (nⴝ99) value Median age (years) White race ⬍High school education Daily vitamin user Marijuana use, past 3 months Hypertension Current smoker Binge drinkera at least monthly Used a home-pregnancy test in past year ⱖTwo partners in past 6 months Periods are usually regular Had no late or missed periods in past 6 months
24 71 11 27 15 18 54 13
24 75 14 35 17 16 56 13
1.00 0.63 0.67 0.28 0.84 0.85 0.89 1.00
59
60
0.99
71
73
0.87
82 57
84 51
0.85 0.48
Binge drinking defined as ⬎6 drinks on one occasion
a
surveys; 87 of these were assigned to the intervention group and 94 to the control group (Figure 1). The remaining women did not return one or both surveys and were unable to be contacted by telephone or mail (16 women), or did not follow the protocol (1 woman). There was no difference in age, race, education, smoking, or drinking between women who did not complete both surveys and those who did complete both surveys. Women were asked how many times they suspected that they might be pregnant during the study period. Four women in the control group and four women in the intervention group did not answer this question on at least one of the two surveys. Among those responding to the question, women in the intervention group suspected that they might be pregnant almost twice as often as women in the control group (2.3 times per woman over 6 months compared to 1.2 times, p⬍0.0001). Once pregnancy was suspected, women in the intervention group were more likely to have a pregnancy test (either at home or in a clinic) than women in the control group (93% of the time versus 64% of the time, p⬍0.0001). Among women who were tested, 100% in the intervention group used at least one home-pregnancy test during the episode compared to 85% in the control group. Women in the intervention group were able to request additional test kits as needed from the research team. Seventy-four percent of women in the intervention group requested at least one additional homepregnancy test. Participants received an average of 2.4 test kits per woman over the study period, including the test kit they received upon entering the study. Overall, 69 women (79%) in the intervention group used at least one pregnancy test compared with 51 (54%) in the control group (p⬍0.001). If women who 152
dropped out of the study were conservatively assumed not to have tested, the difference remained statistically significant (p⫽0.01). Women were asked to give the reasons for pregnancy testing (multiple responses were allowed). Among women who tested, the most common reason for testing was a late period, cited by 71% in the intervention group and 70% in the control group. In each group, 99% said they had no trouble following the directions on the box.
Summary Women were more alert to potential pregnancy and more likely to test for pregnancy if they were supplied with free home-pregnancy test kits. This is the first study to identify an intervention that successfully addresses alertness to pregnancy. Increased alertness is potentially important because it may be associated with earlier recognition of pregnancy. Indirect evidence4 indicates that women who would be expected to be more alert to pregnancy (those actively trying to conceive) recognize pregnancies earlier than those who would be expected to be less alert to pregnancy (those not trying to conceive). Women in the intervention group tested more often when they suspected pregnancy. The acceptability of testing in the intervention group may have been increased by being able to use a test in the privacy of the home13 and by the knowledge that additional free tests were available. Alternatively, the presence of the test kit might have served as a reminder or motivator, resulting women having a lower threshold of suspicion when a period was late. The study used a relatively novel recruitment strategy, based on a purchased mailing list, that was quite successful. Commercial marketing lists are drawn from
Figure 1. Enrollment
American Journal of Preventive Medicine, Volume 36, Number 2
www.ajpm-online.net
numerous data sources, are relatively inexpensive, and can be tailored to some extent. Using a random sample from all available addresses, the study was able to recruit a fully eligible population in a fraction of the time that would have been required had recruitment been solicited through clinic-based settings. The study is subject to several limitations. The population was restricted to low-income, adult women having unprotected intercourse and is not representative of all women in the country. All women in the study were literate and able to speak and read English. Women who choose to participate in a study may be different from those who refrain (selection bias), which affects the generalizability of all studies involving human subjects. However, women who chose to enroll were randomly assigned to the intervention or control group, which makes it highly unlikely that selection bias had an influence on the results within the study population. The study relied on self-reported use of pregnancy tests and suspicion of pregnancy by women in both the control and intervention groups. Thus, it is subject to reporting and recall biases. There is no gold standard to apply in this case to determine if a woman was accurate in reporting that she suspected pregnancy. However, suspecting and testing for pregnancy are not trivial events and are unlikely to be forgotten in a 3-month period. Also, the number of reported cases of pregnancy testing correlated almost exactly with the number of pregnancy tests used in the intervention group. Women in the control group tested more frequently than would have been expected from the baseline survey. There are several possible explanations for this. Filling out surveys and receiving educational material may themselves influence behavior by increasing awareness or suspicion. However, the surveys and educational material were given to both control and intervention women. Thus, the effect would be evenly distributed and would cause an underestimation of the effect of the test kit itself. Such an observational bias would strengthen the results with respect to home-pregnancy test kits. There are some theoretical drawbacks to distributing home test kits. Cost is a factor in any distribution program. However, home-pregnancy test kits are available for less than $1 per test when purchased in bulk, making it financially feasible for Medicaid programs or selected clinics to distribute kits to women at risk. More-frequent pregnancy testing may result in discovery of nonviable pregnancies that would otherwise have remained undetected. This may cause emotional distress. Women may not understand how to use the test and may rely on false results. In the study, all women were able to answer questions about how and when to
February 2009
use the test. Finally, women who wait to be tested in an obstetric clinic may receive prenatal counseling immediately, whereas women who test at home would have to make an appointment. However, many women get tested in urgent care clinics, emergency rooms, or primary care offices that do not provide prenatal counseling. In summary, women in the study population who were supplied with free home-pregnancy test kits were more alert to the potential for pregnancy and more likely to test for pregnancy. Further studies are needed to determine if increased awareness is associated with earlier recognition in women who become pregnant and, ultimately, whether this improves fetal and maternal outcomes. This study was funded by a grant from the Michigan Department of Community Health. No financial disclosures were reported by the authors of this paper.
References 1. Peacock NR, Kelley MA, Carpenter C, et al. Pregnancy discovery and acceptance among low-income primiparous women: a multicultural exploration. Matern Child Health J 2001;5:109 –18. 2. Cook RL, Ostergaard L, Hillier SL, et al. Home screening for sexually transmitted diseases in high-risk young women: randomised controlled trial. Sex Transm Infect 2007;83:286 –91. 3. Phillips KA, Maddala T, Johnson FR. Measuring preferences for health care interventions using conjoint analysis: an application to HIV testing. Health Serv Res 2002;37:1681–705. 4. Kost K, Landry DJ, Darroch JE. Predicting maternal behaviors during pregnancy: does intention status matter? Fam Plann Perspect 1998;30: 79 – 88. 5. Ockene J, Ma Y, Zapka J, Pbert L, Valentine Goins K, Stoddard A. Spontaneous cessation of smoking and alcohol use among low-income pregnant women. Am J Prev Med 2002;23:150 –9. 6. Johnson SF, McCarter RJ, Ferencz C. Changes in alcohol, cigarette, and recreational drug use during pregnancy: implications for intervention. Am J Epidemiol 1987;126:695–702. 7. Hellerstedt W, Pirie P, Lando H, et al. Differences in preconceptional and prenatal behaviors in women with intended and unintended pregnancies. Am J Public Health 1998;88:663– 6. 8. Johnson SF, McCarter RJ, Ferencz C. Changes in alcohol, cigarette, and recreational drug use during pregnancy: implications for intervention. Am J Epidemiol 1987;126:695–702. 9. CDC. Entry into prenatal care—United States, 1989 –1997. MMWR 2000; 48:393– 8. 10. Williams L, Morrow B, Shulman H, Stephens R, D’Angelo D, Fowler CI.PRAMS 2002 surveillance report. Atlanta GA: Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, CDC, 2006. 11. Cole LA, Khanlian SA, Sutton JM, Davies S, Rayburn WF. Accuracy of home pregnancy tests at the time of missed menses. Am J Obstet Gynecol 2004;190:100 –5. 12. Public Health Service. Fertility, family planning, and reproductive health of U.S. women: data from the 2002 National Survey of Family Growth. Series 23, No. 25. 13. Rockett JC, Buck GM, Lynch CD, Perreault SD. The value of home-based collection of biospecimens in reproductive epidemiology. Environ Health Perspect 2004;112:94 –104.
Am J Prev Med 2009;36(2)
153