- Email: [email protected]
The relationship of the nonstress test to gestational age
The relationship of the nonstress test to gestational age Maurice L. Druzin, M.D., Alice Fox, R.N.C., Elizabeth Kogut, R.N.C., and Cynthia Carlson, R.N. New York, New York Five hundred ninety-three nonstress tests were performed on 41 obstetric patients, at gestational ages ranging from 20 to 40 weeks. Diagnoses included 10 cases of prematurity, six cases of diabetes mellitus, five cases of collagen-vascular disease, five cases of poor obstetric history, three cases of cardiac arrhythmia, and one case each of asthma, polyhydramnios, leukemia, nonimmune fetal hydrops; and eight volunteers were without high-risk factors. All neonates had a 5-minute Apgar score >8; 29 neonates weighed ~2500 gm, 12 weighed <2500 gm, and four weighed <1500 gm. One neonate died of prematurity, and one was small for gestational age. There were no congenital anomalies. There was a significant difference in the number of reactive nonstress tests and nonreactive nonstress tests between the 20- to 24-week, 24- to 28-week, 28- to 32-week, and 32- to 36-week gestational age groups. The increased incidence of nonreactive nonstress tests at earlier gestational ages may have clinical implications. (AM J OBSTET GYNECOL 1985;153:386-9.)
Key words: Nonstress test, reactive, nonreactive, gestational age The use of the nonstress test for determination of fetal condition is widespread in modern obstetric practice. 1· 2 Although the reliability of the nonstress test is well documented at 34 to 42 weeks' gestation, 3 there is some question as to how useful the test is prior to 34 weeks' gestation. "Physiologic" nonreactivity apparently makes the test less useful at the early gestational ages.4 However, some investigators have reported on the usefulness of the nonstress test at 28 to 30 weeks 5 and 28 to 44 weeks of gestation. 6 The conti:"action stress test has been considered to be predictive of fetal outcome as early as 28 to 32 weeks' gestation. 7 This study was undertaken to evaluate the nonstress test at various gestational ages, starting at 20 weeks' gestation.
Material and methods Five hundred ninety-three nonstress tests were performed on 41 patients. The gestational age of the patients was between 20 and 40 weeks by menstrual dates. The diagnoses included prematurity in 10 cases, diabetes mellitus in six, cardiovascular disease in five, poor obstetric history in five, fetal cardiac arrhythmia in three, and asthma, polyhydramnios, leukemia, and nonimmune fetal hydrops in one case each. There were eight volunteers without high-risk factors. All patients
From the Department of Obstetrics and Gynecology, The New York Hospital-Cornell Medical Center. Sponsored by the Society for Gynecologic Investigation. Reprint requests: Dr. Maurice L. Druzin, Department of Obstetrics and Gynecology, The New York Hospital-Cornell Medical Center, 525 East 68th St., New York, NY 10021.
386
who were not known to be diabetic had a normal glucose screen (50 gm glucose load with a I-hour plasma glucose of <150 mg/100 ml). Abdominal wall ultrasound technique was used. A reactive nonstress test was defined as two accelerations of the fetal heart rate ~ 15 bpm above the baseline, ~ 15 seconds in duration, associated with fetal movement, within a 20-minute period. A nonreactive nonstress test failed to meet these criteria in two consecutive 20-minute periods. A persistent nonreactive nohstress test was followed by a contraction stress test. A qualifying contraction stress test was defined as one in which there were three contractions in 10 minutes, roughly equal in intensity, and felt by either the patient or the observer. The method of interpreting the contraction stress test was after that of Schifrin et al., 8 with use of the "window" concept. The contraction stress test was performed only in cases in which the gestational age was >28 weeks. Prior to 28 weeks, clinical decisions were not made on the basis of results of the nonstress test.
Results All neonates had a 5-minute Apgar score >8. Twenty-nine neonates weighed ~2500 gm, 12 weighed <2500 gm, and four weighed< 1500 gm. One neonate who weighed 1060 gm died of prematurity, and another was small for gestational age (2215 gm). There were rio congenital anomalies. The rates of reactive and nonreactive tests at 4-week intervals are summarized in Table I. It was noted that, at 20 to 24 weeks, 73% of the tests were nonreactive and 27% were reactive. However, at 24 to 28 weeks, 45% of the nonstress tests were
Relationship of nonstress test to gestational age
Volume 153 Number 4
387
Table I. Incidence of reactive and nonreactive nonstress tests Reactive nonstress test
p Value
Gestational age (wk)
N
I
No.
Non reactive nonstress test
%
No.
I
%
20-24
26
7
27
19
73
24-28
108
59
55
49
45
28-32
152
124
82
28
18
32-36 36-40
188 119
178 118
95 99
10 1
5 1
0.025 0.001 0.001
Table II. Longitudinal follow-up throughout pregnancy, starting prior to 24 weeks' gestation Gestational age (wk)
20-24 Patient
Diagnosis
1 2 3 4
Normal Normal Normal Premature dilatation of cervix Previous stillbirth Normal Collagen-vascular disease Collagen-vascular disease Totals Percentages
5 6 7 8
R
=
R
24-28
I NR
R
28-30
I NR
R
30-32
I NR
R
0 0 0 2
3 3 0
0 0 1
2 2
1
2 4 3 2
0 0 0
4 3 3
1 2 0
4 1 4
2 0 0
0 1 2
3
0
3
5
4
0
3
6 29
71
16 52
12 75
4 25
11 85
Reactive nonstress test. NR
3 1 2 0
0 0
=
I
15
15 48
32-36
I NR 0 0
R
4 4 5 1
I NR 0 0 0 0
8 24
0
0
4
0
2 15
50 98
1 2
36-40 R
I NR
2 3
0 0
7 4 15
0 0
I
Outcome
Normal Normal Normal Normal Normal Normal Normal Normal
31 97
1 3
Nonreactive nonstress test.
nonreactive and 55% were reactive. The difference between the two groups (20 to 24 weeks and 24 to 28 weeks) was statistically significant with a p value of 0.025. After 28 weeks' gestation, at 28 to 32 weeks, the incidence of reactive nonstress tests was 82% and that of nonreactive nonstress tests was 18%; a further breakdown of this group shows 76% reactive nonstress tests and 24% nonreactive nonstress tests at 28 to 30 weeks, and 86% reactive nonstress tests and 14% nonreactive nonstress tests at 30 to 32 weeks. After 32 weeks' gestation, at 32 to 36 weeks, the incidence of reactive nonstress tests was 95% and that of nonreactive nonstress tests was 5%; at 36 to 40 weeks, there were 99% reactive nonstress tests and 1% nonreactive nonstress tests. Therefore, there was a significant difference in the numbers of reactive nonstress tests and nonreactive nonstress tests between the gestational age groups of 20 to 24 weeks, 24 to 28 weeks, 28 to 32 weeks, and 32 to 36 weeks. Eight patients were followed longitudinally throughout their pregnancies, with testing starting prior to 24 weeks. Four were normal volunteers without any identifiable risk factors, two had collagen vascular disorders,
one had had a previous stillbirth, and one had premature dilatation of the cervix. As Tables II and III show, the percentages of reactive and nonreactive tests at different gestational ages in this group compare favorably with the findings in the overall study group. Three patients, all normal volunteers, had reactive tests prior to 24 weeks. Their tests continued to be reactive throughout the pregnancy, and all had totally normal outcomes. In Patients 5 and 8, the tests became reactive after 28 weeks, and all patients had reactive tests after 30 weeks, except for Patient 7, who had reactive tests after 32 weeks.
Comment Gestational age and reactivity of the fetal heart rate have long been known to be related. Of note is that in the 20- to 24-week group, there were at least 25% reactive nonstress tests. Reactivity rose to 55% in the 24to 28-week group. At 28 to 30 weeks, the reactivity rate was 76%, and after 30 weeks, it approached that of term gestations. Although the number of patients studied serially is small, it is of interest that the fetus who had a reactive test at 20 to 24 weeks continued to have
388 Druzin et al.
October 15, 1985 Am J Obstet Gynecol
Table III. Longitudinal follow-up throughout pregnancy, starting prior to 24 weeks' gestation, incidence of reactive nonstress tests at I-week intervals Weeks of gestation Patient
Diagnosis
I
Normal Normal Normal Premature dilatation of cervix Previous stillbirth Normal Collagen-vascular disease Collagen-vascular disease Totals Percentages
2 3 4 5 6
7 8
20
21
22
23
III
Ill
Ill Ill Ill Oil Oil
Ill
Oil
Oil Oil Oil Oil
Oil Oil Oil Oil
Oil Oil Oil
014
216 33
115 20
0
a reactive test until term. Most tests were reactive after 30 weeks, and almost all (81/83) were reactive after 32 weeks. The definition of fetal "viability" in terms of birth weight and gestational age is controversial. Although a fetal weight ;;:.800 gm is considered by most neonatal intensive care units to be compatible with survival and will lead to maximum efforts by the neonatologists, the management of the 600 to 800 gm group is still under much discussion. 9·ll The importance of correlating birth weight and gestational age cannot be overemphasized. A small for gestational age fetus who weighs 750 gm at 28 weeks' gestation because of severe intrauterine growth retardation will have a different prognosis than that of an adequate for gestational age 750 gm fetus at 26 weeks' gestation. In summary, the use of nonstress testing at early gestational ages seems to have clinical application, particularly in the group >28 weeks' gestation. In the 28to 32-week group, a nonreactive nonstress test can be followed by a contraction stress test which has been shown to be predictive in this early gestational age group. 7 Therefore, management decisions can be made with some degree of confidence in terms of impending fetal compromise. Most obstetric services would perform a cesarean section for fetal distress in labor in a gestation estimated to be >28 weeks in duration or at an estimated fetal weight of> 1000 gm. 12 Continuous intrapartum electronic fetal monitoring has been shown to be reliable in the fetus who weighs 1500 gm or less. 13 It would be inconsistent therefore not to act on antepartum indicators of fetal compromise. Application of the nonstress test to gestational ages <28 weeks awaits further study. Use of the biophysical profile and other parameters of testing may be of use in ascertaining those fetuses who are at risk prior to 28 weeks' gestation. 14 In some conditions, such as collagenvascular disease and severe hypertensive diseases, there are fetuses who may be compromised prior to 28 weeks
24
25
26
Ill Ill III Oil Oil
Ill Ill Ill Oil
Oil
ll I Ill Ill Oil Oil Oil Oil
Oil Oil
316 50
317 43
317 43
l/2 111
27 Ill Ill Oil
28
29
30
212
ll I
Ill Oil
212
III III
Ill
Ill Oil Oil
213
212
212
618
618
718
75
75
88
111
Oil
Oil
012
l/2
5110
417
50
57
Oil
.w.
Ill
(birth weight approximately 1000 gm), or prior to 26 weeks (birth weight approximately 800 gm). Identification of a group such as this would lead to optimum use of fetal surveillance techniques at later gestational ages. The use of identical criteria for reactivity at all gestational ages has recently been questioned.4 Further large-scale studies with clinical application of different criteria are necessary. Use of the same criteria for all gestational ages may be less confusing and more clinically applicable until further information is available. We wish to acknowledge the assistance of Audrey M. Waltner in the preparation of the manuscript. REFERENCES I. Weingold AB, Yonekura ML, O'Kieffe]. Stress and non-
stress antepartum fetal monitoring: current status. Obstet Gynecol Annu 1980;9:139. 2. Knuppel RA, Lake M, Ingram JM. A review of the nonstress test.J Reprod Med 1982;27:120. 3. Keegan KA, Paul RH, Broussard PM, McCart D, Smith MA. Antepartum fetal heart rate testing. V. The nonstress test-an outpatient approach. AM J 0BSTET GYNECOL 1980;136:81. 4. Natale R, Nasello C, Turliuk R. The relationship between
movements and accelerations in fetal heart rate at twentyfour to thirty-two weeks' gestation. AM J OBSTET GYNECOL 1984;148:591.
5. Sorokin Y, Dierker LJ, Pillay SK, Zador IE, Schreiner ML, Rosen MG. The association between fetal heart rate patterns and fetal movements in pregnancies between 20 and 30 weeks' gestation. AMJ OBSTET GYNECOL 1982; 143:243. 6. Lavin JP Jr, Miodovnik M, Barden TP. The relationship of nonstress test reactivity and gestational age. Obstet Gynecol 1984;63:338. 7. Gabbe SG, Freeman RK, Goebelsmann U. Evaluation of contraction stress test before 33 weeks gestation. Obstet Gynecol 1978;52:649. 8. Schifrin BS, Lapidus M, Doctor GS, Leviton A. Contraction stress test for antepartum fetal evaluation. Obstet Gynecol 1975;45:433. 9. Hirata T, Epcar JT, Walsh A, Mednick J, Harris M, McGinnis MS, Sehring S, Papedo G. Survival and outcome of infants 501 to 750 gm: a six year experience. J Pediatr 1983; 102:741.
Volume 153 Number 4
31
I
32
l/l Ill
l/l l/l 2/2
Ill
2/3
Oil
ill 4/5 64
Relationship of nonstress test to gestational age 389
I
33
34
35
36-40
Outcome Normal Normal Normal Normal Normal Normal Normal Normal
Ill l/l Ill 2/2
l/l Ill Ill
Ill Ill Ill
Ill 2/2 3/3
2/2
2/2
.m_
.m_
616
616
616
7/8 4/4 15/15
14/15 93
13/13 100
ll/l l 100
ll/ll 100
32/33 97
616
IO. Kitchen W, Ford G, Orgill A, Rickards A, Astbury J, LissendenJ, Bajuk B, Yu V, Drew J, Campbell N. Outcome in infants with birth weight 500 to 900 gm: a regional study of 1979 and 1980 births. J Pediatr 1984;104:921. 11. Bowes WA Jr, Halgrimson M, Simmons MA. Results of the intensive perinatal management of very low birth weight infants (501-1500 gm). J Reprod Med 1979;23: 245. 12. Bowes WA Jr. Delivery of the very low birth weight infant. Clin Perinatol 1981;8:183. 13. Bowes WA Jr, Gabre SG, Bowes C. Fetal heart rate monitoring in premature infants weighing l ,500 grams or less. AM J 0BSTET GYNECOL 1980;137:791. 14. Manning FA, Platt LD, Sipos L. Antepartum fetal evaluation: development of a fetal biophysical profile. AM J 0BSTET GYNECOL 1980;136:787.
Bound volumes available to subscribers Bound volumes of the AMERICAN JOURNAL OF OBSTETRICS AND GYNECOLOGY are available to subscribers (only) for the 1985 issues from the Publisher, at a cost of $74.50 ($95.05 international) for Vol. 151 (January-April), Vol. 152 (May-August), and Vol. 153 (September-December). Shipping charges are included. Each bound volume contains a subject and author index and all advertising is removed. Copies are shipped within 30 days after publication of the last issue in the volume. The binding is durable buckram with the JOURNAL name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact The C. V. Mosby Company, Circulation Department, 11830 Westline Industrial Drive, St. Louis, Missouri 63146, USA; phone (800) 325-4177, ext. 351. Subscriptions must be in force to qualify. Bound volumes are not available in place of a regular JOURNAL subscription.
Key words: Nonstress test, reactive, nonreactive, gestational age The use of the nonstress test for determination of fetal condition is widespread in modern obstetric practice. 1· 2 Although the reliability of the nonstress test is well documented at 34 to 42 weeks' gestation, 3 there is some question as to how useful the test is prior to 34 weeks' gestation. "Physiologic" nonreactivity apparently makes the test less useful at the early gestational ages.4 However, some investigators have reported on the usefulness of the nonstress test at 28 to 30 weeks 5 and 28 to 44 weeks of gestation. 6 The conti:"action stress test has been considered to be predictive of fetal outcome as early as 28 to 32 weeks' gestation. 7 This study was undertaken to evaluate the nonstress test at various gestational ages, starting at 20 weeks' gestation.
Material and methods Five hundred ninety-three nonstress tests were performed on 41 patients. The gestational age of the patients was between 20 and 40 weeks by menstrual dates. The diagnoses included prematurity in 10 cases, diabetes mellitus in six, cardiovascular disease in five, poor obstetric history in five, fetal cardiac arrhythmia in three, and asthma, polyhydramnios, leukemia, and nonimmune fetal hydrops in one case each. There were eight volunteers without high-risk factors. All patients
From the Department of Obstetrics and Gynecology, The New York Hospital-Cornell Medical Center. Sponsored by the Society for Gynecologic Investigation. Reprint requests: Dr. Maurice L. Druzin, Department of Obstetrics and Gynecology, The New York Hospital-Cornell Medical Center, 525 East 68th St., New York, NY 10021.
386
who were not known to be diabetic had a normal glucose screen (50 gm glucose load with a I-hour plasma glucose of <150 mg/100 ml). Abdominal wall ultrasound technique was used. A reactive nonstress test was defined as two accelerations of the fetal heart rate ~ 15 bpm above the baseline, ~ 15 seconds in duration, associated with fetal movement, within a 20-minute period. A nonreactive nonstress test failed to meet these criteria in two consecutive 20-minute periods. A persistent nonreactive nohstress test was followed by a contraction stress test. A qualifying contraction stress test was defined as one in which there were three contractions in 10 minutes, roughly equal in intensity, and felt by either the patient or the observer. The method of interpreting the contraction stress test was after that of Schifrin et al., 8 with use of the "window" concept. The contraction stress test was performed only in cases in which the gestational age was >28 weeks. Prior to 28 weeks, clinical decisions were not made on the basis of results of the nonstress test.
Results All neonates had a 5-minute Apgar score >8. Twenty-nine neonates weighed ~2500 gm, 12 weighed <2500 gm, and four weighed< 1500 gm. One neonate who weighed 1060 gm died of prematurity, and another was small for gestational age (2215 gm). There were rio congenital anomalies. The rates of reactive and nonreactive tests at 4-week intervals are summarized in Table I. It was noted that, at 20 to 24 weeks, 73% of the tests were nonreactive and 27% were reactive. However, at 24 to 28 weeks, 45% of the nonstress tests were
Relationship of nonstress test to gestational age
Volume 153 Number 4
387
Table I. Incidence of reactive and nonreactive nonstress tests Reactive nonstress test
p Value
Gestational age (wk)
N
I
No.
Non reactive nonstress test
%
No.
I
%
20-24
26
7
27
19
73
24-28
108
59
55
49
45
28-32
152
124
82
28
18
32-36 36-40
188 119
178 118
95 99
10 1
5 1
0.025 0.001 0.001
Table II. Longitudinal follow-up throughout pregnancy, starting prior to 24 weeks' gestation Gestational age (wk)
20-24 Patient
Diagnosis
1 2 3 4
Normal Normal Normal Premature dilatation of cervix Previous stillbirth Normal Collagen-vascular disease Collagen-vascular disease Totals Percentages
5 6 7 8
R
=
R
24-28
I NR
R
28-30
I NR
R
30-32
I NR
R
0 0 0 2
3 3 0
0 0 1
2 2
1
2 4 3 2
0 0 0
4 3 3
1 2 0
4 1 4
2 0 0
0 1 2
3
0
3
5
4
0
3
6 29
71
16 52
12 75
4 25
11 85
Reactive nonstress test. NR
3 1 2 0
0 0
=
I
15
15 48
32-36
I NR 0 0
R
4 4 5 1
I NR 0 0 0 0
8 24
0
0
4
0
2 15
50 98
1 2
36-40 R
I NR
2 3
0 0
7 4 15
0 0
I
Outcome
Normal Normal Normal Normal Normal Normal Normal Normal
31 97
1 3
Nonreactive nonstress test.
nonreactive and 55% were reactive. The difference between the two groups (20 to 24 weeks and 24 to 28 weeks) was statistically significant with a p value of 0.025. After 28 weeks' gestation, at 28 to 32 weeks, the incidence of reactive nonstress tests was 82% and that of nonreactive nonstress tests was 18%; a further breakdown of this group shows 76% reactive nonstress tests and 24% nonreactive nonstress tests at 28 to 30 weeks, and 86% reactive nonstress tests and 14% nonreactive nonstress tests at 30 to 32 weeks. After 32 weeks' gestation, at 32 to 36 weeks, the incidence of reactive nonstress tests was 95% and that of nonreactive nonstress tests was 5%; at 36 to 40 weeks, there were 99% reactive nonstress tests and 1% nonreactive nonstress tests. Therefore, there was a significant difference in the numbers of reactive nonstress tests and nonreactive nonstress tests between the gestational age groups of 20 to 24 weeks, 24 to 28 weeks, 28 to 32 weeks, and 32 to 36 weeks. Eight patients were followed longitudinally throughout their pregnancies, with testing starting prior to 24 weeks. Four were normal volunteers without any identifiable risk factors, two had collagen vascular disorders,
one had had a previous stillbirth, and one had premature dilatation of the cervix. As Tables II and III show, the percentages of reactive and nonreactive tests at different gestational ages in this group compare favorably with the findings in the overall study group. Three patients, all normal volunteers, had reactive tests prior to 24 weeks. Their tests continued to be reactive throughout the pregnancy, and all had totally normal outcomes. In Patients 5 and 8, the tests became reactive after 28 weeks, and all patients had reactive tests after 30 weeks, except for Patient 7, who had reactive tests after 32 weeks.
Comment Gestational age and reactivity of the fetal heart rate have long been known to be related. Of note is that in the 20- to 24-week group, there were at least 25% reactive nonstress tests. Reactivity rose to 55% in the 24to 28-week group. At 28 to 30 weeks, the reactivity rate was 76%, and after 30 weeks, it approached that of term gestations. Although the number of patients studied serially is small, it is of interest that the fetus who had a reactive test at 20 to 24 weeks continued to have
388 Druzin et al.
October 15, 1985 Am J Obstet Gynecol
Table III. Longitudinal follow-up throughout pregnancy, starting prior to 24 weeks' gestation, incidence of reactive nonstress tests at I-week intervals Weeks of gestation Patient
Diagnosis
I
Normal Normal Normal Premature dilatation of cervix Previous stillbirth Normal Collagen-vascular disease Collagen-vascular disease Totals Percentages
2 3 4 5 6
7 8
20
21
22
23
III
Ill
Ill Ill Ill Oil Oil
Ill
Oil
Oil Oil Oil Oil
Oil Oil Oil Oil
Oil Oil Oil
014
216 33
115 20
0
a reactive test until term. Most tests were reactive after 30 weeks, and almost all (81/83) were reactive after 32 weeks. The definition of fetal "viability" in terms of birth weight and gestational age is controversial. Although a fetal weight ;;:.800 gm is considered by most neonatal intensive care units to be compatible with survival and will lead to maximum efforts by the neonatologists, the management of the 600 to 800 gm group is still under much discussion. 9·ll The importance of correlating birth weight and gestational age cannot be overemphasized. A small for gestational age fetus who weighs 750 gm at 28 weeks' gestation because of severe intrauterine growth retardation will have a different prognosis than that of an adequate for gestational age 750 gm fetus at 26 weeks' gestation. In summary, the use of nonstress testing at early gestational ages seems to have clinical application, particularly in the group >28 weeks' gestation. In the 28to 32-week group, a nonreactive nonstress test can be followed by a contraction stress test which has been shown to be predictive in this early gestational age group. 7 Therefore, management decisions can be made with some degree of confidence in terms of impending fetal compromise. Most obstetric services would perform a cesarean section for fetal distress in labor in a gestation estimated to be >28 weeks in duration or at an estimated fetal weight of> 1000 gm. 12 Continuous intrapartum electronic fetal monitoring has been shown to be reliable in the fetus who weighs 1500 gm or less. 13 It would be inconsistent therefore not to act on antepartum indicators of fetal compromise. Application of the nonstress test to gestational ages <28 weeks awaits further study. Use of the biophysical profile and other parameters of testing may be of use in ascertaining those fetuses who are at risk prior to 28 weeks' gestation. 14 In some conditions, such as collagenvascular disease and severe hypertensive diseases, there are fetuses who may be compromised prior to 28 weeks
24
25
26
Ill Ill III Oil Oil
Ill Ill Ill Oil
Oil
ll I Ill Ill Oil Oil Oil Oil
Oil Oil
316 50
317 43
317 43
l/2 111
27 Ill Ill Oil
28
29
30
212
ll I
Ill Oil
212
III III
Ill
Ill Oil Oil
213
212
212
618
618
718
75
75
88
111
Oil
Oil
012
l/2
5110
417
50
57
Oil
.w.
Ill
(birth weight approximately 1000 gm), or prior to 26 weeks (birth weight approximately 800 gm). Identification of a group such as this would lead to optimum use of fetal surveillance techniques at later gestational ages. The use of identical criteria for reactivity at all gestational ages has recently been questioned.4 Further large-scale studies with clinical application of different criteria are necessary. Use of the same criteria for all gestational ages may be less confusing and more clinically applicable until further information is available. We wish to acknowledge the assistance of Audrey M. Waltner in the preparation of the manuscript. REFERENCES I. Weingold AB, Yonekura ML, O'Kieffe]. Stress and non-
stress antepartum fetal monitoring: current status. Obstet Gynecol Annu 1980;9:139. 2. Knuppel RA, Lake M, Ingram JM. A review of the nonstress test.J Reprod Med 1982;27:120. 3. Keegan KA, Paul RH, Broussard PM, McCart D, Smith MA. Antepartum fetal heart rate testing. V. The nonstress test-an outpatient approach. AM J 0BSTET GYNECOL 1980;136:81. 4. Natale R, Nasello C, Turliuk R. The relationship between
movements and accelerations in fetal heart rate at twentyfour to thirty-two weeks' gestation. AM J OBSTET GYNECOL 1984;148:591.
5. Sorokin Y, Dierker LJ, Pillay SK, Zador IE, Schreiner ML, Rosen MG. The association between fetal heart rate patterns and fetal movements in pregnancies between 20 and 30 weeks' gestation. AMJ OBSTET GYNECOL 1982; 143:243. 6. Lavin JP Jr, Miodovnik M, Barden TP. The relationship of nonstress test reactivity and gestational age. Obstet Gynecol 1984;63:338. 7. Gabbe SG, Freeman RK, Goebelsmann U. Evaluation of contraction stress test before 33 weeks gestation. Obstet Gynecol 1978;52:649. 8. Schifrin BS, Lapidus M, Doctor GS, Leviton A. Contraction stress test for antepartum fetal evaluation. Obstet Gynecol 1975;45:433. 9. Hirata T, Epcar JT, Walsh A, Mednick J, Harris M, McGinnis MS, Sehring S, Papedo G. Survival and outcome of infants 501 to 750 gm: a six year experience. J Pediatr 1983; 102:741.
Volume 153 Number 4
31
I
32
l/l Ill
l/l l/l 2/2
Ill
2/3
Oil
ill 4/5 64
Relationship of nonstress test to gestational age 389
I
33
34
35
36-40
Outcome Normal Normal Normal Normal Normal Normal Normal Normal
Ill l/l Ill 2/2
l/l Ill Ill
Ill Ill Ill
Ill 2/2 3/3
2/2
2/2
.m_
.m_
616
616
616
7/8 4/4 15/15
14/15 93
13/13 100
ll/l l 100
ll/ll 100
32/33 97
616
IO. Kitchen W, Ford G, Orgill A, Rickards A, Astbury J, LissendenJ, Bajuk B, Yu V, Drew J, Campbell N. Outcome in infants with birth weight 500 to 900 gm: a regional study of 1979 and 1980 births. J Pediatr 1984;104:921. 11. Bowes WA Jr, Halgrimson M, Simmons MA. Results of the intensive perinatal management of very low birth weight infants (501-1500 gm). J Reprod Med 1979;23: 245. 12. Bowes WA Jr. Delivery of the very low birth weight infant. Clin Perinatol 1981;8:183. 13. Bowes WA Jr, Gabre SG, Bowes C. Fetal heart rate monitoring in premature infants weighing l ,500 grams or less. AM J 0BSTET GYNECOL 1980;137:791. 14. Manning FA, Platt LD, Sipos L. Antepartum fetal evaluation: development of a fetal biophysical profile. AM J 0BSTET GYNECOL 1980;136:787.
Bound volumes available to subscribers Bound volumes of the AMERICAN JOURNAL OF OBSTETRICS AND GYNECOLOGY are available to subscribers (only) for the 1985 issues from the Publisher, at a cost of $74.50 ($95.05 international) for Vol. 151 (January-April), Vol. 152 (May-August), and Vol. 153 (September-December). Shipping charges are included. Each bound volume contains a subject and author index and all advertising is removed. Copies are shipped within 30 days after publication of the last issue in the volume. The binding is durable buckram with the JOURNAL name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact The C. V. Mosby Company, Circulation Department, 11830 Westline Industrial Drive, St. Louis, Missouri 63146, USA; phone (800) 325-4177, ext. 351. Subscriptions must be in force to qualify. Bound volumes are not available in place of a regular JOURNAL subscription.