Severe oligohydramnios with intact membranes: an indication for diagnostic amnioinfusion

OBJECTIVE

To quantify the improvement in ultrasonographic fetal imaging following diagnostic amnioinfusion for the indication of unexplained midtrimester oligohydramnios.

METHODS

Patients referred for unexplained midtrimester oligohydramnios were retrospectively reviewed. Videotapes of those undergoing diagnostic antenatal amnioinfusion were analyzed for quality of visualization of routinely imaged structures before and after the infusion procedure.

RESULTS

The overall rate of adequate visualization of fetal structures improved from 50.98 to 76.79% (p < 0.0001). In fetuses having preinfusion-identified obstructive uropathy, there was improvement in identification of associated anomalies from 11.8 to 31.3%.

CONCLUSIONS

Several authors have suggested that diagnostic amnioinfusion can facilitate fetal imaging and increase diagnostic precision in the setting of unexplained severe oligohydramnios. We have quantified the improvement in the rate of optimal visualization of fetal structures which likely translates, in experienced hands, into this observed improved diagnostic precision. Of particular importance is the improvement in appreciation of associated anomalies in cases of obstructive uropathy in which such findings may determine whether or not invasive fetal therapy is indicated.

Obstetrical determinants of neonatal neurological morbidity in < or = 1000-gram infants

The purpose of this study is to identify obstetrical factors associated with adverse neurological outcome in < or =1000-g infants. In a 1-year (1992-1993) observational study, the NICHD MFMU Network collected obstetrical risk factors for 486 infants who weighed < or =1000 g at birth and who survived > 2 days. Infants' records were abstracted for seizures, intraventricular hemorrhage, and an abnormal neurological evaluation. Seventy-nine (16%) infants had a Grade III or IV intraventricular hemorrhage, 46 (9%) developed seizures and 57 (14%) had an abnormal neurological evaluation. Both lower birth weight and earlier gestational age correlated (P <0.01) with an increasing incidence of all three outcomes. Several other factors appeared to be associated with neurological morbidity, however, after controlling for potential confounders in the multivariate analyses, most of these factors were no longer significant. African-American race, odds ratio (OR) 0.6 (0.3-1.0), and severe preeclampsia, OR 0.2 (0.1-0.7), were protective against intraventricular hemorrhage. Maternal treatment with corticosteroids did not impact neurological outcome in this study population. We conclude that, in a population of < or =1000-g infants, lower birth weight and earlier gestational age were the only consistently significant predictors of all three adverse neurological outcomes.

Induction of labor in patients with term premature rupture of membranes. Effect on perinatal outcome

OBJECTIVE

To determine whether delayed induction of labor in patients with premature rupture of membranes (PROM) at term has beneficial effects on the mother or the infant.

STUDY DESIGN

Retrospective analysis of our database revealed 576 patients >37 weeks of gestation with PROM, who delivered live-born infants without major congenital anomalies. We analyzed the frequencies of primary cesarean, neonatal intensive care unit (NICU) admissions, and oxytocin use by time since hospital admission and interval until onset of labor.

RESULTS

NICU admission increased from 1.9% in <3 h between admission to onset of labor to 13.3% after >18 h. Admission-onset of labor interval, birth weight of <2,500 or >4,000 g and meconium were all more important determinants of NICU admission than gestational age, duration of labor, PROM, and ROM. Prolonged admission-onset of labor interval was associated with an increased risk of variable decelerations (p < 0.001). Primary cesarean rates increased progressively with longer intervals between admission and onset of labor. Stepwise discriminant function analysis revealed that labor duration, admission-onset of labor interval, gestational age, and birth weight of <2,500 g were all more important determinants of primary cesarean delivery than the durations of PROM or ROM.

CONCLUSIONS

The increased frequencies of NICU admission, variable decelerations, and primary cesarean suggest that delayed labor induction after hospital admission was linked to worsened perinatal outcomes. These results may have been influenced by usually performing a single digital examination as part of initial evaluation of term patients who present with PROM. Based on our data, we suggest immediate induction for PROM at term, especially if digital examination has been performed.

The effect of maternal magnesium sulfate treatment on neonatal morbidity in < or = 1000-gram infants

We evaluated the effect of maternal magnesium sulfate treatment on selected neonatal outcomes in < or =1000-g infants. In a 1-year (1992-1993) observational study, the National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units collected outcome data for 799 infants whose birth weights were < or =1000 g. Only singleton infants, with a gestational age >20 weeks who were not the product of an induced abortion were included. Our analysis was further limited to those infants without major congenital anomalies, who were deemed potentially viable by the obstetrician, whose mother would have undergone a cesarean delivery for fetal indications, and who survived greater than 2 days. Outcomes were compared in infants whose mothers did and did not receive magnesium sulfate for labor tocolysis. Among the 124 women who did and the 184 who did not receive magnesium sulfate tocolytic therapy, the frequencies of grade III or IV intraventricular hemorrhage (16 vs. 20%, p = 0.34), seizure activity (7 vs. 10%, p = 0.35), grade III or IV retinopathy of prematurity (21 vs. 18% p = 0.59), abnormal neurological exam (28 vs. 28%, p = 0.91), intact survival to 120 days or to discharge (48 vs. 44%, p = 0.54), and infant mortality (23 vs. 31%, p = 0.10) were similar. Multiple logistic regression analysis was used to control for the effect of potential confounders (specifically, gestational age) and confirmed the lack of a significant association between maternal magnesium sulfate treatment for tocolysis and selected neonatal outcomes in this population of < or =1000-gram infants.

Benefits of maternal corticosteroid therapy in infants weighing </=1000 grams at birth after preterm rupture of the amnion

OBJECTIVE

The aim of the study was to determine the effects of antenatal maternal corticosteroid treatment on selected neonatal outcomes in infants weighing </=1000 g at birth after preterm rupture of membranes.

STUDY DESIGN

In a 1-year (1992-1993) prospective observational study, the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network collected outcome data for 766 infants who did not have a major fetal anomaly and who had a birth weight </=1000 g (378 were born after preterm rupture of membranes). Only fetuses deemed potentially viable by the obstetrician were included in our analysis. Selected neonatal outcomes were compared between mothers who did and did not receive antenatal corticosteroids. Logistic regression variables included birth weight, sex, race, amnionitis, tocolytic therapies, mode of delivery, and surfactant use.

RESULTS

Two hundred fourteen of the 378 infants whose mothers had preterm rupture of membranes were deemed potentially viable; 62 of these mothers received antenatal steroids and 152 did not. Groups were similar with respect to gestational age, birth weight, race, amnionitis, and delivery mode. Women who received antenatal steroids were more likely to have received tocolysis (P <.001). Univariate and regression analyses controlling for multiple confounders confirmed no neonatal benefits of maternal corticosteroid use.

CONCLUSIONS

Corticosteroid treatment in women with preterm rupture of membranes was of no apparent benefit to neonates weighing </=1000 g.

Indicated versus spontaneous preterm delivery: An evaluation of neonatal morbidity among infants weighing </=1000 grams at birth

OBJECTIVE

The aim of the study was to determine whether infants weighing </=1000 g after birth who are born to women who undergo indicated preterm delivery have different neonatal outcomes than do those born as a result of either spontaneous preterm labor or preterm premature rupture of membranes.

STUDY DESIGN

In a 1-year observational study (1992-1993) the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network collected outcome data for 799 infants whose birth weights were </=1000 g. Only singleton infants with gestational age >20 weeks who were not produced as the result of an induced abortion were included. Our analysis was further limited to infants without major congenital anomalies who survived >2 days, were deemed potentially viable by the obstetrician, and would have undergone a cesarean delivery for fetal indications (N = 411). The primary reason for delivery was categorized as indicated delivery, spontaneous preterm labor, or spontaneous preterm premature rupture of membranes. Selected neonatal outcomes were evaluated among infants born to women in each of these groups. Logistic regression analyses were used to control for the effects of other potentially confounding variables.

RESULTS

A total of 156 of the 411 infants were born to women who underwent an indicated preterm delivery, whereas 160 were born after spontaneous preterm labor and 95 were delivered after preterm premature rupture of membranes. Univariate analyses revealed significantly lower incidences of grade III or IV intraventricular hemorrhage, grade III or IV retinopathy of prematurity, and seizure activity among infants born in an indicated preterm delivery than among those born after spontaneous preterm labor or preterm premature rupture of membranes. However, infants of women who underwent indicated preterm delivery had a more advanced mean gestational age at birth than did those born after spontaneous preterm labor or preterm premature rupture of membranes (28 +/- 2 weeks, 26 +/- 2 weeks, and 26 +/- 1 weeks, respectively, P <.001). Multiple logistic regression analysis was therefore used to control for the disparity in gestational age. Multivariate analyses did not confirm the apparent improvement in neonatal outcome in the indicated delivery group.

CONCLUSION

In this population of infants weighing </=1000 g, selected neonatal outcomes did not differ according to birth by indicated preterm delivery, spontaneous preterm labor, or preterm premature rupture of membranes.

Obstetric determinants of neonatal survival: antenatal predictors of neonatal survival and morbidity in extremely low birth weight infants

OBJECTIVE

The aim of the study was to compare clinical and ultrasonographic variables obtained before delivery as predictors of neonatal survival and morbidity in infants weighing </=1000 g at birth.

STUDY DESIGN

Maternal data available before the birth of singleton infants with birth weights </=1000 g who were delivered at the 11 tertiary perinatal centers of the National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Research Units were studied. Births that followed extramural delivery, antepartum stillbirths, multiple gestations, induced abortions, infants with major malformations, and fetuses delivered at <20 weeks' gestation were excluded. Ultrasonographic variables, including estimated fetal weight, obstetrically estimated gestational age, femur length, and biparietal diameter, and clinical variables, such as maternal race, antenatal care, substance abuse, medical treatment, reason for delivery, fetal gender, and presentation, were studied with logistic regression as predictors of neonatal outcome, including intrapartum stillbirth, neonatal death, and survival to 120 days after birth or to discharge from the hospital with or without the presence of markers of major morbidity.

RESULTS

Eight hundred eight infants met enrollment criteria; 63 were excluded because of incomplete data and 32 were excluded because of malformations, leaving 713 for analysis, 386 of whom had an ultrasonographic examination within 3 days of delivery that recorded femur length, biparietal diameter, and estimated fetal weight. Forty-two percent of births were the result of preterm labor, 22% were the result of preterm ruptured membranes, 12% were the result of preeclampsia or eclampsia, 9% were the result of fetal distress, 4% were the result of placenta previa or abruptio placentae, and 2% were the result of intrauterine growth restriction. Perinatal mortality before 24 weeks' gestation exceeded 81% (19% stillbirths and 62% neonatal deaths) but declined sharply thereafter. Most survivors born before 26 weeks' gestation had serious morbidity. Fetal femur length and estimated gestational age predicted survival better than did biparietal diameter or estimated fetal weight. Infants who survived with markers of serious long-term morbidity could not be distinguished from those who survived without morbidity markers before delivery by ultrasonography or clinical data. Threshold values for ultrasonographic measurements of biparietal diameter and femur length were developed to distinguish fetuses with no chance of survival.

CONCLUSION

Ultrasonographic assessment of either fetal femur length or gestational age predicts neonatal mortality better than do other antenatal tests. No tests accurately predicted neonatal morbidity in infants weighing </=1000 g at birth.

Plasma ferritin, premature rupture of membranes, and pregnancy outcome

OBJECTIVE

The objective of this study was to determine whether plasma ferritin levels predict maternal or neonatal outcomes in women with preterm rupture of membranes at <32 weeks' gestation.

METHODS

Plasma from 223 women with premature rupture of membranes at <32 weeks' gestation who had participated in a randomized antibiotic trial were analyzed for ferritin at random assignment and at delivery, and the results were compared with the development of clinical chorioamnionitis, latency until delivery, neonatal sepsis, and a composite adverse neonatal outcome variable.

RESULTS

The mean plasma ferritin level rose from 19.2 +/- 29.1 microgram/L on admission to 38.3 +/- 54.3 microgram/L at delivery, with a mean latency of 9.3 +/- 14.6 days. Plasma ferritin levels were significantly higher at both times in mothers whose infants acquired sepsis than in those whose infants did not, especially at delivery (68.5 +/- 96.3 microgram/L vs 32.5 +/- 40.5 microgram/L, P =.01), and neonatal sepsis was 2 to 3 times more common among women with plasma ferritin levels above the median than among those with levels below the median.

CONCLUSIONS

Among women with premature rupture of membranes at <32 weeks' gestation, plasma ferritin levels were significantly associated with neonatal sepsis. These data suggest that higher plasma ferritin levels may serve as a marker of infection among women with premature rupture of membranes; however, the clinical utility of plasma ferritin levels in predicting neonatal outcome appears limited.

Limited usefulness of fetal weight in predicting neonatal brachial plexus injury

OBJECTIVE

The objectives were to determine the neonatal morbidity rate from vaginal birth and examine fetal weight-based injury-prevention strategies.

STUDY DESIGN

Selected neonatal morbidities were categorized by birth weight for all vertex vaginal deliveries occurring during a 12-year period. Sensitivity, specificity, and predictive values for brachial palsy were calculated at increasing birth weight cutoff levels. A policy of cesarean delivery for macrosomic infants was evaluated.

RESULTS

There were 80 cases of brachial palsy among 63,761 infants (0.13%). In mothers without diabetes, rates in the 4500- to 4999-g and >5000-g groups were 3.0% and 6.7%, respectively. A threshold of 3700 g had a sensitivity of 71% and a specificity of 86%; the positive predictive value was 0.56%. To prevent a single case of permanent injury, 155 to 588 cesarean deliveries are required at the currently recommended cutoff weight of 4500 g.

CONCLUSIONS

The rates of lasting morbidity do not justify routine cesarean delivery for infants without diabetic complications weighing <5000 g.

The preterm prediction study: risk factors for indicated preterm births. Maternal-Fetal Medicine Units Network of the National Institute of Child Health and Human Development

OBJECTIVE

Preterm births occur for many different reasons. Most efforts to identify risk factors for preterm births either ignore cause and consider preterm births as a single entity or examine risk factors for spontaneous preterm births. We performed this study to examine risk factors for indicated preterm births, which constitute more than one quarter of all preterm births.

STUDY DESIGN

The study included 2929 women evaluated at 24 weeks' gestation at 10 centers. Information was gathered about demographic factors, socioeconomic status, home and work environments, drug and alcohol use, and medical history. In addition vaginal samples were evaluated for fetal fibronectin and bacterial vaginosis and cervical length was measured by transvaginal ultrasonography. Associations with indicated preterm birth were evaluated by univariate tests and by multivariable analysis with logistic regression.

RESULTS

Of the women studied at 24 weeks' gestation 15.3% were delivered of their infants at <37 weeks' gestation. Of these deliveries, 27.7% were indicated preterm births. Risk factors in the final multivariable model were, in order of decreasing odds ratios, mullerian duct abnormality (odds ratio 7.02), proteinuria at <24 weeks' gestation (odds ratio 5.85), history of chronic hypertension (odds ratio 4.06), history of previous indicated preterm birth (odds ratio 2.79), history of lung disease (odds ratio 2.52), previous spontaneous preterm birth (odds ratio 2.45), age >30 years (odds ratio 2.42), black ethnicity (odds ratio 1.56), and working during pregnancy (odds ratio 1.49). Alcohol use in pregnancy was actually associated with a lower risk of indicated preterm birth (odds ratio 0.35).

CONCLUSION

The risk factors found in this analysis tend to be different from those associated with spontaneous preterm birth.

The preterm prediction study: the value of new vs standard risk factors in predicting early and all spontaneous preterm births. NICHD MFMU Network

OBJECTIVES

This study was undertaken to determine the relationship between fetal fibronectin, short cervix, bacterial vaginosis, other traditional risk factors, and spontaneous preterm birth.

METHODS

From 1992 through 1994, 2929 women were screened at the gestational age 22 to 24 weeks.

RESULTS

The odds ratios for spontaneous preterm birth were highest for fetal fibronectin, followed by a short cervix and history of preterm birth. These factors, as well as bacterial vaginosis, were more strongly associated with early than with late spontaneous preterm birth. Bacterial vaginosis was more common--and a stronger predictor of spontaneous preterm birth--in Black women, while body mass index less than 19.8 was a stronger predictor in non-Black women. This analysis suggests a pathway leading from Black race through bacterial vaginosis and fetal fibronectin to spontaneous preterm birth. Prior preterm birth is associated with spontaneous preterm birth through a short cervix.

CONCLUSIONS

Fetal fibronectin and a short cervix are stronger predictors of spontaneous preterm birth than traditional risk factors. Bacterial vaginosis was found more often in Black than in non-Black women and accounted for 40% of the attributable risk for spontaneous preterm birth at less than 32 weeks.

The incidence of respiratory distress syndrome does not increase when preterm delivery occurs greater than 7 days after steroid administration

We sought to determine if the risk of the respiratory distress syndrome (RDS) is increased when preterm delivery occurs greater than 7 days from the last steroid administration. At our hospital, steroids were repeated weekly only on inpatients. Linking pharmacy and delivery records, we analyzed the risk of RDS with preterm delivery by interval since last steroid administration. Discriminant function analysis revealed that adjusted for gestational age, there was a negative correlation between interval since last steroids administration and risk for RDS (p<0.05, n=254). Using analysis of variance to control more precisely for gestational age (28-32 weeks, n=19) we found no difference in the risk for RDS with longer intervals since the last steroid administration. We then used multiway contingency analysis to consider intervals as zero to 7 versus greater than 7 days and similar results were obtained. Our findings suggest that the process of pulmonary maturation induced by steroid administration is permanent rather than transient. Repetitive steroid administration does not appear to be beneficial. Only a large, prospective randomized trial could definitively address the issue of repeat steroid administration. However, on the basis of our findings and review of available literature, we believe there is insufficient data to recommend weekly repeat steroid administration to women at risk for preterm delivery.

Antibiotic therapy for reduction of infant morbidity after preterm premature rupture of the membranes. A randomized controlled trial. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network

CONTEXT

Intrauterine infection is thought to be one cause of preterm premature rupture of the membranes (PPROM). Antibiotic therapy has been shown to prolong pregnancy, but the effect on infant morbidity has been inconsistent.

OBJECTIVE

To determine if antibiotic treatment during expectant management of PPROM will reduce infant morbidity.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

University hospitals of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

PATIENTS

A total of 614 of 804 eligible gravidas with PPROM between 24 weeks' and 0 days' and 32 weeks' and 0 days' gestation who were considered candidates for pregnancy prolongation and had not received corticosteroids for fetal maturation or antibiotic treatment within 1 week of randomization.

INTERVENTIONS

Intravenous ampicillin (2-g dose every 6 hours) and erythromycin (250-mg dose every 6 hours) for 48 hours followed by oral amoxicillin (250-mg dose every 8 hours) and erythromycin base (333-mg dose every 8 hours) for 5 days vs a matching placebo regimen. Group B streptococcus (GBS) carriers were identified and treated. Tocolysis and corticosteroids were prohibited after randomization.

MAIN OUTCOME MEASURES

The composite primary outcome included pregnancies complicated by at least one of the following: fetal or infant death, respiratory distress, severe intraventricular hemorrhage, stage 2 or 3 necrotizing enterocolitis, or sepsis within 72 hours of birth. These perinatal morbidities were also evaluated individually and pregnancy prolongation was assessed.

RESULTS

In the total study population, the primary outcome (44.1 % vs 52.9%; P=.04), respiratory distress (40.5% vs 48.7%; P=.04), and necrotizing enterocolitis (2.3% vs 5.8%; P=.03) were less frequent with antibiotics. In the GBS-negative cohort, the antibiotic group had less frequent primary outcome (44.5% vs 54.5%; P=.03), respiratory distress (40.8% vs 50.6%; P=.03), overall sepsis (8.4% vs 15.6%; P=.01), pneumonia (2.9% vs 7.0%; P=.04), and other morbidities. Among GBS-negative women, significant pregnancy prolongation was seen with antibiotics (P<.001).

CONCLUSIONS

We recommend that women with expectantly managed PPROM remote from term receive antibiotics to reduce infant morbidity.

Vascular disruption birth defects and history of prenatal cocaine exposure: a case control study

OBJECTIVE

To test the hypothesis that prenatal cocaine exposure is associated with a 3-fold increased risk for vascular disruption among malformations.

STUDY DESIGN

A retrospective case-control study was based upon >68,000 delivery records at Hutzel Hospital for a 9-year period. Ascertainment was based upon ICD-9 codes for limb defects, abdominal wall defects, and facial clefts. Transverse limb defects and gastroschisis were defined as cases, and nondisruption anomalies served as controls. Statistical analysis for history of maternal cocaine use reported during pregnancy was performed by chi(2) analysis and the odds ratio determined.

RESULTS

A total of 190 cases of limb anomalies, abdominal wall defects, and cleft lips were identified after exclusion criteria. Statistical analysis was performed on the 119 cases informative for maternal cocaine use during pregnancy. Seven of 34 vascular disruption cases had cocaine exposure reported versus 12 of 85 other malformations controls. The odds ratio for cocaine exposure and vascular disruption is 1.58 (95% confidence interval = 0.55-4.47).

CONCLUSION

The putative association of prenatal cocaine exposure and vascular disruption birth defects remains unresolved, but the attributable risk is very likely less than the 3-fold odds ratio previously reported.

The Preterm Prediction Study: association of cesarean delivery with increases in maternal weight and body mass index

OBJECTIVE

Our purpose was to evaluate whether maternal weight and body mass index measured either before or during pregnancy are associated with an increased risk of cesarean delivery.

STUDY DESIGN

Maternal weight and height were prospectively collected on 2929 women in the National Institutes of Health Maternal-Fetal Medicine Units Network Preterm Prediction Study. Prepregnancy and 27- to 31-week maternal weight and height were used to calculate the body mass index, and its contribution to the risk of cesarean delivery was determined. Women with prenatally diagnosed congenital anomalies (n = 89) and pregestational diabetes (n = 31) were excluded from analysis.

RESULTS

Univariate analysis of risk factors for cesarean delivery in the 2809 eligible women revealed a decreased risk of cesarean delivery with maternal age < 18 years and multiparity; increased risk of cesarean delivery was noted with maternal age > 35 years and a male fetus. Increases in either prepregnancy or 27- to 31-week maternal weight (5-pound units) or body mass index (1.0 kg/m2 units) were significantly associated with an increased odds of cesarean delivery (p = 0.0001). Each unit increase in prepregnancy or 27- to 31-week body mass index resulted in a parallel increase in the odds of cesarean delivery of 7.0% and 7.8%, respectively. Multivariable stepwise logistic regression analysis confirmed the association of male fetus, age, nulliparity, and body mass index as significant variables contributing to cesarean delivery risk.

CONCLUSIONS

The risk of cesarean delivery is associated with incremental changes in maternal weight and body mass index before and during pregnancy after adjustment for potential confounding factors. Prepregnancy counseling about optimizing maternal weight and monitoring weight gain during pregnancy to decrease the risk of cesarean delivery are supported by this study.

In utero progression of isolated renal pelvis dilation

The objective of this study to determine the risk of in uteroprogression of renal pelvis dilation when detected on antenatal ultrasound examination. We reviewed 230 fetuses with evidence of renal pelvis dilation. At least one exam was subsequently performed prior to delivery in all cases. Renal pelvis dilation was defined as an anterior-posterior renal pelvis measurement > 4 mm at < 32 weeks' and > 7 mm at > or = 32 weeks' gestation. Hydronephrosis was considered to be present when the renal pelvis measured +10 mm independent of gestational age. Multiple gestations and fetuses with additional congenital anomalies were excluded. The mean gestational age at diagnosis was 24 weeks. Renal pelvis dilation progressed to hydronephrosis in a total of 10.9% (25 of 230) of fetuses. There was a 3.3% chance of unilateral renal pelvis dilation progressing to hydronephrosis versus 26.0% in bilateral dilation (OR 10.4 [95% Cl 3.5-33.3]). Of those fetuses with progression, 80% had bilateral dilation (p < 0.0001). There was no difference in progression between right and left kidneys. Additionally, gender, gestational age at diagnosis and delivery, and birth weight did not differ between those fetuses with and without progression. The hydronephrosis in 7 of 25 (28%) regressed to pyelectasis on a subsequent ultrasound exam. Thus, the overall rate of progression of renal pelvis dilation to persistent hydronephrosis was 7.8% (18 of 230). In conclusion, the risk of isolated renal pelvis dilation progressing to hydronephrosis is low. Although bilateral pelvis dilation carries a higher risk for progression, no fetus in our study required in utero intervention. A follow up scan prior to delivery may be considered to identify those fetuses who will require postpartum intervention.

Isolated mild ventriculomegaly: associated karyotypic abnormalities and in utero observations

OBJECTIVE

The incidence of abnormal chromosomes in fetuses with mild lateral ventriculomegaly as an isolated prenatal ultrasound finding is not well established, and the rate of progression to more severe ventriculomegaly is uncertain. We wished to better define both the incidence of karyotypic abnormalities and the in utero course of fetuses with isolated mild ventriculomegaly.

SUBJECTS AND METHODS

From July 1992 to September 1994, all cases of mild ventriculomegaly at our institution were reviewed (N = 94). Forty-six were isolated. Of these, 25 had genetic evaluation, and 37 had serial ultrasound examination. We evaluated the frequencies of karyotype abnormality and in utero progression for atrial measurements of 11-15 mm.

RESULTS

In fetuses with atria 11-15 mm, three of the 25 karyotypes were abnormal (47 XXY and two 47 + 21, giving an incidence of 12% (95% CI 4.2-30.1%). Of the 37 with serial scans, five resolved in utero, 11 remained unchanged, and 20 progressed (one beyond 15 mm).

CONCLUSION

Isolated mild ventriculomegaly is associated with a significantly increased incidence of chromosomal abnormalities. Therefore, these patients should be offered genetic testing. When mild and isolated, some fetuses will show in utero resolution of the ventriculomegaly. Progression to more severe degrees of hydrocephalus is uncommon.

The preterm prediction study: patterns of cervicovaginal fetal fibronectin as predictors of spontaneous preterm delivery. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network

OBJECTIVE

Our purpose was to determine how various temporal patterns of fetal fibronectin positivity from 24 to 30 weeks predict subsequent fetal fibronectin test results and spontaneous preterm delivery.

STUDY DESIGN

A total of 2929 women had vaginal and cervical fetal fibronectin tests obtained at least once at 24, 26, 28, or 30 weeks, and 1870 women had tests performed at all four gestational ages. Fetal fibronectin values > or = 50 ng/ml were considered positive. Various patterns of positive and negative tests were evaluated for prediction of (1) whether the next fetal fibronectin test would be positive or negative and (2) the percent of women with a spontaneous preterm delivery > or = 4 weeks after the last fetal fibronectin test at < 30, < 32, < 35, and < 37 weeks' gestational age.

RESULTS

Women with previous negative test results had only a 3% chance of a subsequent positive test result; however, if the last test result was positive, 29% of the next tests were positive. Of the 1870 women with tests at 24, 26, 28, and 30 weeks, 89% had all negative results, 8.4% had one positive result, 1.8% had two positive results, and 0.8% had three or four positive results. The higher the percent of positive tests at 24 to 26 weeks, at 28 to 30 weeks, or at 24 to 30 weeks, the greater the risk of subsequent spontaneous preterm birth. As an example, the risk of spontaneous preterm birth at < 30 weeks for women with two negative fetal fibronectin test results at 24 and 26 weeks was 0.3% versus 16% for women with two positive results.

CONCLUSION

The presence of a positive cervical or vaginal fetal fibronectin test result predicts subsequent positive fetal fibronectin positivity and subsequent spontaneous preterm birth. The greater the percent of positive results, the higher is the risk of spontaneous preterm birth. After a positive test result, two negative results are required before the risk of spontaneous preterm birth returns to baseline.

Determining blood pressure in pregnancy. Positional hydrostatic effects

OBJECTIVE

To evaluate positional hydrostatic effects on blood pressure determination during pregnancy.

STUDY DESIGN

We studied 30 normotensive, pregnant women at 34-41 weeks of gestation. Blood pressures were taken in the sitting, left lateral, right lateral and supine positions with a two-minute stabilization period between positions. The bisacromial diameter was measured. Multivariate analysis of variance for repeated measures was used to evaluate the affect of position on blood pressure.

RESULTS

Mean systolic pressure in the right arm was 2.6 mm Hg greater than that in the left arm (P < .05). There was no difference between the arms in diastolic blood pressure. Immediate blood pressure in the lower arm was no greater than in the higher arm in lateral positions, and there were no other significant positional effects. Observed blood pressures were significantly different than those theoretically expected on the basis of hydrostatic effects (P < .0001).

CONCLUSION

Positional effects on blood pressure in the lateral positions do not appear immediately (within two minutes), indicating that hydrostatic pressure does not account for these changes. The well-documented blood pressure reduction from longer duration in the lateral position does not appear to be an artifact of hydrostatic effect. Repositioning pregnant women in the supine position to have the cuff at the level of the heart is unnecessary and often undesirable when fetal perfusion is an important consideration. We suggest that American Heart Association blood pressure guidelines stating that all measurements be taken with the cuff at the level of the heart to avoid hydrostatic pressure change be revised for pregnancy.

Meconium does not guarantee fetal lung maturity

OBJECTIVE

In utero passage of meconium may represent a response to hypoxic stress or a normal maturational event. When found during the third trimester, one may be tempted to use its presence as prima facie evidence of fetal lung maturity. The purpose of our study was to determine the frequency of meconium-stained fluid in the third trimester and the incidence of biochemical and physiologic lung immaturity in these fetuses.

METHODS

Amniotic fluid specimens obtained at our institution from 1991 through 1993 (n = 2,377) were analyzed for maturity and visually inspected for meconium. Perinatal outcome was obtained for intramural deliveries occurring within 3 days of amniotic fluid collection (n = 905). Gestational age was defined as the best obstetric estimate based on menstrual dates, clinical examination, and ultrasound results.

RESULTS

Meconium staining was present in 2.7% (n = 64) of specimens. Although meconium-stained specimens were more likely to have mature lecithin-sphingomyelin (L:S) ratios (OR 2.1, 95% confidence interval [CI] = 1.2-3.6) and phosphatidylglycerol (PG) concentrations (OR 3.8, CI 2.2-6.7), 17.2% were immature for both L:S and PG (n = 11, CI = 9.9-28.2%). When analysis was limited to fetuses delivering intramurally within 3 days of amniotic fluid collection, respiratory distress syndrome occurred in 3.0% (CI = 0.5-15%) with meconium-stained fluid.

CONCLUSIONS

The presence of meconium in amniotic fluid does not guarantee lung maturity. The same consideration of the risks of prematurity must be given to the fetus with meconium-stained fluid as given to the fetus with clear fluid.

Obstetric determinants of neonatal survival: influence of willingness to perform cesarean delivery on survival of extremely low-birth-weight infants. National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units

OBJECTIVE

Our purpose was to evaluate the relationship between the approach to obstetric management and survival of extremely low-birth-weight infants.

STUDY DESIGN

In this prospective observational study we evaluated 713 singleton births of infants weighing < or = 1000 gm during 1 year at the 11 tertiary perinatal care centers of the National Institutes of Child Health and Human Development network of maternal-fetal medicine units. Major anomalies, extramural delivery, antepartum stillbirth, induced abortion, and gestational age < 21 weeks were excluded. The obstetrician's opinion of viability and willingness to perform cesarean delivery in the event of fetal distress were ascertained from the medical record or interview when documentation was unclear. Grade 3 and 4 intraventricular hemorrhage, grade 3 and 4 retinopathy of prematurity, necrotizing enterocolitis requiring surgery, oxygen dependence at discharge or 120 days, and seizures were considered serious morbidity. Survival without serious morbidity was considered intact survival. Logistic regression was used to evaluate the influence of the approach to obstetric management, adjusted for birth weight, growth, gender, presentation, and ethnicity.

RESULTS

Willingness to perform cesarean delivery was associated with increased likelihood of both survival (adjusted odds ratio 3.7, 95% confidence interval 2.3 to 6.0) and intact survival (adjusted odds ratio 1.8, 95% confidence interval 1.0 to 3.3). Willingness to intervene for fetal indications appeared to virtually eliminate intrapartum stillbirth and to reduce neonatal mortality. Below 800 gm or 26 weeks, however, willingness to perform cesarean delivery was linked to an increased chance of survival with serious morbidity. Although obstetricians were willing to intervene for fetal indications in most cases by 24 weeks, willingness to perform cesarean delivery was associated with twice the risk for serious morbidity at that gestational age.

CONCLUSIONS

The approach to obstetric management significantly influences the outcome of extremely low-birth-weight infants. Above 800 gm or 26 weeks the obstetrician should usually be willing to perform cesarean delivery for fetal indications. Between 22 and 25 weeks willingness to intervene results in greater likelihood of both intact survival and survival with serious morbidity. In these cases patients and physicians should be aware of the impact of the approach to obstetric management and consider the likelihood of serious morbidity and mortality when formulating plans for delivery.

Transvaginal ultrasonography for all placentas that appear to be low-lying or over the internal cervical os

The purpose of this study was to determine in what percentage of cases the assessment of placental localization using transabdominal sonography (TAS) was changed after transvaginal sonography (TVS) was applied. TVS was prospectively performed on all pregnant women of at least 15 weeks' gestation, when the placental edge using TAS appeared to be over or within 2 cm (low-lying) of the internal cervical os. The time required for the TVS scan and the distance of the placental edge from the internal cervical os were recorded. Of the 168 patients entered into the study, 131 were analyzed. Landmarks were poorly seen in 50% of the cases when using TAS. In 66 cases, the placenta appeared low or possibly over the internal cervical os using TAS, but a definitive diagnosis could not be made due to suboptimal visualization. In the remaining 65 cases, visualization of the internal os and placental edge was possible using both TAS and TVS. In this group, there was a change in the diagnosis in 26% of the cases after TVS was performed. Our results suggest that optimal visualization of the placental edge and internal cervical os is usually difficult with TAS when the placenta appears low-lying or over the internal cervical os. The assessment of placental localization was changed in over one-quarter of cases (26%) after transvaginal sonography was performed. The use of transvaginal ultrasound should be seriously considered when the placenta appears to be low or over the internal cervical os by transabdominal ultrasound.

The use of second-trimester transvaginal sonography to predict placenta previa

Our objective was to determine the incidence and rate of persistence of placenta previa diagnosed at 15-20 weeks' gestation by using transvaginal sonography (TVS), and to describe the characteristics of TVS that predict placenta previa at delivery. Patients having placental tissue within 20 mm of the cervical os were prospectively identified by transabdominal ultrasound and underwent TVS. The distance of the placental edge from the cervical os was measured in millimeters. Characteristics of TVS predicting placenta previa at delivery were analyzed by logistic regression. The incidence of placenta previa diagnosed by TVS at 15-20 weeks was 1.1%; 14% persisted until delivery. Gestational age at the time of TVS and the distance of the placental edge to the cervical os helped predict placenta previa at delivery. Between 15 and 24 weeks' gestation, placenta overlapping the internal os by > or = 10 mm identified patients at risk of placenta previa at delivery with 100% sensitivity and 85% specificity. The use of TVS in the second trimester to diagnose placenta previa resulted in a lower incidence than was historically reported with the use of transabdominal ultrasound. The distance of the placental edge from the cervical os helps identify patients at risk of previa at delivery.

Maternal syphilis: the next pregnancy

We sought to determine: (1) the perinatal outcomes in the subsequent pregnancy; (2) the natural history of serologic titers over the course of the two pregnancies; and (3) the incidence and risk factors for delivering an infant with congenital syphilis in the subsequent pregnancy. Over a five-year period, we reviewed the charts of 46 women with maternal syphilis during pregnancy who had a subsequent pregnancy and delivered in our institution. The initial and subsequent pregnancy outcomes were contrasted. To characterize the subsequent pregnancy risk of congenital syphilis, those women with recurrent congenital syphilis were contrasted to women who delivered infants without congenital syphilis. Rapid plasma reagin (RPR) titers in the initial and subsequent pregnancy were analyzed by neonatal outcome. Forty percent of the women who delivered an infant with congenital syphilis in their first pregnancy delivered yet another infant with congenital syphilis in the subsequent pregnancy. Continued cocaine use was the single most important risk factor for delivering another infant with congenital syphilis (p < 0.0001). Forty-two percent of the women who delivered an infant without congenital syphilis in the initial pregnancy delivered an infant with congenital syphilis in the subsequent pregnancy. Birthweight, the number of neonatal hospital days, and the incidence of respiratory distress syndrome (RDS), neonatal pneumonia, abruption, and positive meconium drug screens were not significantly different between the initial and subsequent pregnancies. As with the initial pregnancy, women continued to experience poor pregnancy outcomes in the subsequent pregnancy.

Is the 50-gram glucose screening test ever diagnostic?

The standard criteria for the diagnosis of gestational diabetes (GDM) is based on two abnormal values of a 3-h-100-g oral glucose tolerance test (GTT). Although a markedly elevated 1 h-50-g screen value has been suggested to support a diagnosis of GDM, limited data are available to substantiate this empiric observation. Our purpose was to examine the utility of various 50-g screen cutoff values in establishing the diagnosis of gestational diabetes. We identified 422 gravidas with a positive 50-g screen (> or = 135 mg/dl) who underwent additional glucose testing. GDM was defined according to the National Diabetes Data Group (NDDG) standards for the 3-h GTT. An analysis employing the criteria of Carpenter and Coustan was performed for comparison. If a patient had an elevated 50-g value and no 3-h GTT was performed, a fasting serum glucose > or = 140 mg/ dl was considered evidence of gestational diabetes. One hundred twenty four (29.4%) had GDM as defined by the NDDG criteria; this increased to 161 (38%) when the diagnosis was based on Carpenter and Coustan's criteria. The mean (+/- SD) gestational age at screening was 24 +/- 7 weeks. As expected, the prevalence of GDM increased in relation to an increasing 50-g value. All subjects with a 50-g screen > 216 mg/dl had evidence of gestational diabetes and required insulin for glycemic control. Patients with a 50-g screen > or = 220 mg/dl do not all require a 3-h GTT. Those with a fasting serum glucose of > or = 140 mg/dl may begin diet therapy, glucose monitoring, and insulin as indicated. If the fasting serum glucose is < 140 mg/dl, a 3-h GTT should be performed for confirmation of GDM. This approach will facilitate rapid therapeutic intervention and reduce the cost of care in this subset of patients. Gravidas with a very high 50-g screen are at significant risk of requiring insulin to maintain euglycemia during pregnancy.

Lung maturity tests. Relation to source, clarity, gestational age and neonatal outcome

OBJECTIVE

To determine whether gestational age is a significant determinant of neonatal outcome, irrespective of biochemical lung maturity. The effects of specimen source and clarity on the reliability of biochemical tests for predicting respiratory distress syndrome are also evaluated.

STUDY DESIGN

Perinatal outcome was analyzed for 904 neonates undergoing amniotic fluid maturity studies within three days of delivery from 1991 to 1993. The relationships of gestational age and biochemical maturity to neonatal outcome were examined using multivariate analysis of covariance. Test reliability was evaluated using log-linear analysis of multiway frequency tables.

RESULTS

Gestational age was a better predictor of neonatal outcome than biochemical lung maturity. Gestational age significantly correlated with every measure of outcome except intraventricular hemorrhage and jaundice. Test reliability was not significantly influenced by specimen source or clarity.

CONCLUSION

Results obtained using contaminated amniotic fluid are reliable when the proper technique is used. Irrespective of biochemical maturity, neonatal outcome is significantly related to gestational age. Gestational age, and not just biochemical maturity, should be considered when timing delivery.

The preterm prediction study: a clinical risk assessment system

OBJECTIVE

Our aims were to develop a risk assessment system for the prediction of spontaneous preterm delivery using clinical information available at 23 to 24 weeks' gestation and to determine the predictive value of such a system.

STUDY DESIGN

A total of 2929 women were evaluated between 23 and 24 weeks' gestation at 10 centers. Demographic factors, socioeconomic status, home and work environment, drug and alcohol use, and medical history were evaluated. Information regarding symptoms, cultures, and treatments in the current pregnancy were ascertained. Anthropomorphic and cervical examinations were performed. Univariate analysis and multivariate logistic regression were performed in a random selection, constituting 85% of the study population. The derived risk assessment system was applied to the remaining 15% of the population to evaluate its validity.

RESULTS

A total of 10.4% of women were delivered of preterm infants. The multivariate models for spontaneous preterm delivery were highly associated with spontaneous preterm delivery (p < 0.0001). A low body mass index (<19.8) and increasing Bishop scores were significantly associated with spontaneous preterm delivery in nulliparous and multiparous women. Black race, poor social environment, and work during pregnancy were associated with increased risk for nulliparous women. Prior obstetric outcome overshadowed socioeconomic risk factors in multiparous women with a twofold increase in the odds of spontaneous preterm delivery for each prior spontaneous preterm delivery. Current pregnancy symptoms, including vaginal bleeding, symptomatic contractions within 2 weeks, and acute or chronic lung disease were variably associated with spontaneous preterm delivery in nulliparous and multiparous women. When the system was applied to the remainder of the population, women defined to be at high risk for spontaneous preterm delivery (> or = 20% risk) carried a 3.8-fold (nulliparous women) and 3.3-fold (multiparous women) higher risk of spontaneous preterm delivery than those predicted to be at low risk. However, the risk assessment system identified a minority of women who had spontaneous preterm deliveries. The sensitivities were 24.2% and 18.2% and positive predictive values were 28.6% and 33.3%, respectively, for nulliparous and multiparous women.

CONCLUSIONS

Although it is possible to develop a graded risk assessment system that includes factors that are highly associated with spontaneous preterm delivery in nulliparous and multiparous women, such a system does not identify most women who subsequently have a spontaneous preterm delivery. This system has investigational value as the basis for evaluating new technologies designed to identify at-risk subpopulations.

Brain natriuretic peptide and cyclic guanosine-3',5' monophosphate in pre-eclampsia

The objective of this study is to determine the possibility that pre-eclampsia, a disease characterized by altered vascular tone, may result in altered levels of fetal BNP and cGMP, and to determine whether pre-eclampsia alters the maternal-fetal relationship of BNP and cGMP. Paired maternal and umbilical venous plasma levels of BNP and cGMP were determined in 13 pre-eclamptic and 9 normotensive primigravidas in the third trimester. Statistical analysis was performed using multivariate analysis of variance, linear regression, and canonical correlation. Overall, levels of cGMP were lower in pre-eclampsia (P < 0.03). Pre-eclampsia was also associated with an altered maternal-fetal relationship for BNP and cGMP (P < 0.008, P < 0.02, respectively). With pre-eclampsia, the maternal:fetal ratio was reduced for BNP and was increased for cGMP. Because of its role as a second messenger for many vasoactive hormones, we hypothesize that fetal cGMP levels may better reflect overall vascular tone than do individual hormones. Altered BNP and cGMP maternal-fetal homeostasis raises the possibility of maternal-fetal coordination of vascular control.

Changes in health care delivery: a threat to academic obstetrics

OBJECTIVE

Our purpose was to examine the effect of anticipated health care policy changes on delivery trends at leading academic obstetric institutions.

STUDY DESIGN

The 51 centers in the United States with the most Society of Perinatal Obstetricians presentations in the past 2 years were surveyed regarding annual deliveries from 1990 to 1993 and reasons for any changes. Analysis of variance and chi 2 analysis were used as appropriate.

RESULTS

Complete data were available from 43 hospitals representing 39 institutions. Their 1990 to 1993 delivery rates declined faster than United States delivery rates (12.3% vs 2.0%, p < 0.0001). The largest hospitals (> 6000 deliveries) had a decline of 18.2% compared with declines of 9.0% for medium and 0.9% for small hospitals (< 2500 deliveries). Regionally the greatest impact was seen in the West and the South, with 22% and 12% declines, respectively (p < 0.05). Reasons cited for the decline included competition from private or community physicians or hospitals (59%) and managed care (15%).

CONCLUSION

As the national health care debate focuses on cost containment and coverage, we believe the potential effects of national policy on research and education should be considered. Continued selective reduction in deliveries at academic institutions can be expected to adversely affect research and education.

Computer-generated admission forms have greater accuracy

We examined the accuracy of computer-generated admission forms to standardized handwritten admission forms for 40 patient records. There was a mean of 8.3 errors among handwritten forms but only 0.9 errors among computerized forms (p < 0.0001). Written forms had seven serious errors versus one for computerized forms (p < 0.05). We conclude that computerized admission forms have superior accuracy.

Underappreciated risks of the elderly multipara

OBJECTIVE

Our purpose was to identify the age-related increased risks of the elderly gravida by clarifying the effects of age and parity, their combination, and their interaction.

STUDY DESIGN

We studied 9556 singleton pregnancies in women aged 20 to 29 years or > or = 35 years delivered over an 8-year period. Data were analyzed by stepwise multiway contingency table analysis, with p < 0.002 considered significant.

RESULTS

Many of the previously reported risks of the elderly gravida are expected on the basis of age and parity. Significant associations (primarily related to advanced age) included higher frequencies of obesity, chronic hypertension, gestational diabetes, and large-for-gestational-age and macrosomic infants. These elderly gravidas, on the other hand, had fewer postdates pregnancies. Although often overlooked, the greatest age-related increases in risk for induction (1.8 times), preeclampsia (2.7 times), gestational diabetes (4.5 times), clinical diabetes (3.2 times), oxytocin use (1.7 times), and macrosomia (1.6 times) occur in multiparas, not nulliparas. The risk for preeclampsia in the elderly multipara is significantly higher than expected on the basis of age and parity.

CONCLUSION

The increased risks of the elderly multipara may have been overshadowed by the previous focus on the elderly nullipara. It is important to recognize the increases in age-related risks of the elderly multipara to appropriately counsel and manage this group of patients.

Maternal syphilis in Michigan: the challenge to prevent congenital syphilis

Syphilis has re-emerged as a significant public health problem for pregnant women and their babies in Michigan, US, and in many areas of the world. In the US over 50,000 cases of primary and secondary syphilis were reported to the Centers for Disease Control (CDC) in 1990. Due to the current epidemic of maternal syphilis in pregnancy in our city, we studied 253 cases of maternal syphilis over a one-year period. Our objective was to determine maternal risk factors during pregnancy predicting congenital infection. Women with high venereal disease research laboratory (VDRL) titres during pregnancy and unknown duration of disease had the highest incidence of delivering an infant with congenital syphilis. Even with treatment according to the current CDC guidelines there was a 27% incidence of congenital syphilis if disease duration was < 1 year and a 49% incidence of congenital syphilis for unknown duration of disease. Maternal syphilis during pregnancy was associated with significant neonatal morbidity and a preterm delivery incidence of 28%. The clinical evaluation, management, and current treatment guidelines are reviewed in this paper.

Comparison of intrauterine hematologic and biochemical values between twin pairs with and without stuck twin syndrome

OBJECTIVE

Our purpose was to compare hematologic and biochemical values in cordocentesis specimens from twin pairs with and without stuck twin syndrome.

STUDY DESIGN

Cordocentesis was performed on 38 twin pairs. Assignment to the stuck twin syndrome group (n = 8) was based on ultrasonographic findings of discordant size and amniotic fluid volume, concordant gender, and a single placenta. A receiver-operator characteristic curve was constructed with the use of intertwin hemoglobin differences. For the stuck twin syndrome group regression analysis of gestational age and intertwin hemoglobin difference was done.

RESULTS

We found significant (p = 0.03) intertwin differences in hemoglobin between the stuck twin syndrome group (mean 5.35 gm/dl, range 0.5 to 15.4 gm/dl) and the comparison group (mean 0.10 gm/dl, range 0.0 to 2.4 gm/dl). A nearly significant relationship between gestational age and intertwin hemoglobin difference was noted in the stuck twin syndrome group. When the hemoglobin difference was > 2.4 gm/dl, all cases had stuck twin syndrome (sensitivity = 50%, specificity = 100%, positive predictive value = 100%, negative predictive value = 91%). In the stuck twin syndrome group there was a trend toward larger intertwin differences in albumin and total protein. Intertwin blood gas values between the groups did not differ, but the average PO2 was lower when the smaller twins of the two groups were compared.

CONCLUSION

An intertwin difference in hemoglobin > 2.4 gm/dl is consistent with stuck twin syndrome. Large intertwin hemoglobin differences and imbalances in albumin and total protein may be seen in stuck twin syndrome.

Centile-based ultrasound morphometric tables

Current ultrasound morphometric tables estimate centiles assuming normal distribution and similar variation throughout gestation. Our goal was to develop normative tables for biparietal diameter, femur length and average abdominal diameter using actual centiles. We studied the last complete ultrasound examination from 9510 singleton, live pregnancies without major malformations delivered at our hospital. Actual 5th, 10th, 50th, 90th and 95th centiles were calculated for each week and compared to estimates based on means and standard deviations. With advancing gestational age, variation in average abdominal diameter increased and variation in biparietal diameter and femur length remained stable. The largest difference between an actual and an estimated centile limit was 2 mm for biparietal diameter or femur length and 3 mm for average abdominal diameter. Differences between true and estimated centile limits were less than the intraobserver variation of the ultrasound measurements and therefore clinically unimportant.

Third stage of labor: analysis of duration and clinical practice

OBJECTIVES

Our purpose was to record gestational age-specific data for third-stage duration of labor, frequencies of retained placentas (undelivered at 30 minutes), manual removal of the placenta, and hemorrhage.

STUDY DESIGN

Included were 45,852 singleton deliveries > or = 20 weeks' gestation from 1984 to 1992. Odds ratios, 95% confidence intervals, and actuarial life analysis with censoring of cases with manual placenta removal were performed.

RESULTS

The frequency of retained placentas (2.0% overall) was markedly increased among gestations < or = 26 weeks (odds ratio 20.8, 95% confidence interval 17.1 to 25.4) and < 37 weeks (odds ratio 3.0, 95% confidence interval 2.6 to 3.5) compared with term. The frequency of manual removal (3.0% overall) was increased among gestations < or = 26 weeks (odds ratio 9.2, 95% confidence interval 7.5 to 11.4) and < 37 weeks (odds ratio 2.8, 95% confidence interval 2.4 to 3.1) compared with term. Hemorrhage (3.5% overall) was increased among subjects with manual placenta removal (odds ratio 10.4, 95% confidence interval 9.1 to 11.9); hemorrhage was also increased among gestations < or = 26 weeks (odds ratio 3.0, 95% confidence interval 2.3 to 4.0) and < 37 weeks (odds ratio 1.2, 95% confidence interval 1.01 to 1.3) compared with term. The frequency of hemorrhage peaked by 40 minutes regardless of gestational age. Life-table analysis predicted 90% of placentas would spontaneously deliver by 180 minutes for gestations at 20 weeks, 21 minutes at 30 weeks, and 14 minutes at 40 weeks; the predicted frequency of retained placentas was 42% higher than the recorded incidence.

CONCLUSIONS

The duration of the third stage decreases and the frequencies of hemorrhage and manual removal decrease with increasing gestational age. Hemorrhage was associated with manual placental removal. Life-table analysis indicated that manual removal of placentas shortened the duration of the third stage of labor, especially among preterm deliveries. A prospective trial is needed to determine whether manual placental removal can reduce hemorrhage among prolonged third stages.

Perinatal outcome of broken marriage in the inner city

OBJECTIVE

To test the hypothesis that the erosion of family structure, epidemic substance abuse, and increased low birth weight (LBW) rates are interrelated.

METHODS

In this cohort study, we analyzed information coded prospectively in a computerized perinatal data base. Separated, divorced, and widowed mothers were grouped as broken marriages. The setting was a predominantly urban, indigent population in a tertiary care hospital. The analysis included singleton pregnancies of 14,896 women receiving prenatal and intrapartum care at our hospital from 1986-1991. The main outcome measures included LBW, prematurity, small for gestational age, neonatal mortality, and neonatal intensive care unit admissions.

RESULTS

Married mothers fared better than single mothers, but risks for adverse perinatal outcomes for women with broken marriages were consistently as high or higher than for single mothers. The rate of LBW infants was 43% higher in the broken marriage group than in the married group. The increased frequency of LBW among infants born into broken marriages was attributable mainly to reduced growth rather than to prematurity and was associated with substance abuse.

CONCLUSION

Our findings indicate that mothers from broken marriages are at relatively higher risk for LBW infants than married mothers (odds ratio 1.5). Broken marriage warrants emphasis as an important perinatal risk factor.

Amnioinfusion: does the choice of solution adversely affect neonatal electrolyte balance?

OBJECTIVE

To determine whether various solutions commonly used in amnioinfusion during labor affect neonatal electrolyte and blood gas values.

METHODS

Amnioinfusion for thick meconium or severe variable fetal heart rate decelerations is used at our institution according to a standardized protocol. During alternating 3-week periods, the only solution made available for amnioinfusion was either normal saline or Ringer's lactate. Bolus volume, rate, and duration of infusion were determined by the individual physicians. At delivery, cord blood was collected for electrolyte and blood gas determination. These values were compared between the two solution groups and to a non-infused control group.

RESULTS

Complete data on neonatal electrolytes and blood gas values were available on 53 infusion patients (20 Ringer's lactate, 33 normal saline) and 39 non-infusion patients. Comparing infusion to non-infusion patients and those infused with Ringer's lactate to those with normal saline, we found no significant difference in demographics, neonatal outcome variables, duration of labor, neonatal electrolytes, and cord blood gas values. Infusion variables (bolus volume, infusion rate, hours infused, and total volume infused) did not differ between solutions. Total volume and hours of infusion were closely correlated with each other (r = 0.93, P < .001); both were correlated with neonatal chloride (r = 0.38 and r = 0.36, respectively; P < .005). No cases of hypernatremia or hyperchloremia were found in any of the groups. The type of solution used had no effect on the neonatal chloride trend.

CONCLUSION

The use of both normal saline and Ringer's lactate for indicated amnioinfusion in labor appears to have no clinically significant effect on neonatal electrolytes.

Hemostasis and diagnosis of preeclampsia

The diagnosis of preeclampsia, with all of its consequences, is at times difficult to establish, especially when the patient has underlying chronic hypertension and is not known from prior prenatal care visits. Many screening tests have been proposed. These should be sensitive, relatively specific, easy to perform, of low cost, and have a reasonable interval from prediction to disease onset. Laboratory assays would obviously be useful. We evaluated hemostasis tests for the diagnosis of preeclampsia, and compared fibronectin, antithrombin III and alpha 2-antiplasmin in 48 preeclamptics and 86 control nulliparas. Receive operator characteristic (ROC) curve analysis suggested that fibronectin is the most effective of these tests. A similar analysis comparing the results of previous studies using serum iron, angiotensin infusion, urinary calcium/creatinine ratio, the rollover test and uric acid suggested a possible role for fibronectin in the diagnosis of preeclampsia. While not ideal, there seems to be, at present, no other, easy to perform laboratory test that outperforms fibronectin in predicting preeclampsia.

Epidemic syphilis: maternal factors associated with congenital infection

OBJECTIVE

Little is known about which cases of maternal syphilis will affect the newborn. Because of the current epidemic of syphilis in pregnancy in our city, we sought to identify risk factors during pregnancy associated with congenital infection.

STUDY DESIGN

We reviewed 253 cases of maternal syphilis prospectively identified over a 1-year period. On the basis of neonatal diagnosis, these data were divided into two groups, those without evidence of presumptive congenital syphilis and those with evidence of presumptive congenital syphilis. Presumptive congenital syphilis was defined according to the Centers for Disease Control and Prevention surveillance case definition. Cases with bloody spinal taps and cases of suspected congenital syphilis that did not meet these criteria were excluded. Venereal Disease Research Laboratory titers are given as the inverse of the geometric mean.

RESULTS

Venereal Disease Research Laboratory titer at time of diagnosis and unknown duration of disease were risk factors for congenital syphilis. There was a significantly decreased rate of congenital syphilis with single-dose therapy if disease length was < 1 year (p < 0.005). Unknown duration of disease was associated with 67.9% and 48.6% rates of congenital syphilis with one- and three-dose therapy respectively. There was a 28% incidence of preterm birth.

CONCLUSION

Our study suggests an alarming rate of failure of current therapy to prevent congenital syphilis. Venereal Disease Research Laboratory titer at time of diagnosis and unknown duration of disease are risk factors for congenital syphilis. The high rate of presumptive congenital syphilis in the unknown duration group indicates that identification before or earlier in pregnancy will be necessary to prevent devastating consequences for the neonate.

Accelerated pulmonary maturation from preterm premature rupture of membranes: a myth

OBJECTIVES

It is widely believed that premature rupture of membranes accelerates fetal pulmonary maturity. The purpose of our study was to determine the duration of premature rupture of the membranes required to achieve this effect.

STUDY DESIGN

Retrospective analysis of our database yielded a group of 1395 patients who were delivered between 24 and 35 weeks' gestation and for whom we had complete data. The frequencies of premature rupture of the membranes and respiratory distress syndrome by each gestational week were analyzed with a log linear multiway contingency table analysis. Because gestational age was based on pediatric examination and was therefore somewhat subjective, birth weight was used to confirm results. Additional factors related to respiratory distress syndrome were considered in stepwise discriminant analysis. Results were further verified by the 1980 National Natality Survey data set.

RESULTS

When we controlled for either gestational age or birth weight, there was no significant difference in the frequency of respiratory distress syndrome related to premature rupture of the membranes, but there was a suggestion (p < 0.08) that respiratory distress syndrome was actually more frequent after premature rupture of the membranes. Stepwise discriminant analysis revealed that gestational age, birth weight, race, sex, and Apgar score at 1 minute were all more important determinants than duration of premature rupture of the membranes. Duration of premature rupture of the membranes was associated with an increased risk of respiratory distress syndrome. Amnionitis was found to be highly related to the duration of premature rupture of the membranes. The incidence of amnionitis significantly increased 24 hours after premature rupture of the membranes occurred. A multiway frequency contingency table of the National Natality Survey data showed a significant increase in respiratory distress syndrome in association with premature rupture of the membranes.

CONCLUSIONS

Pulmonary maturation continues but is not accelerated after premature rupture of the membranes. In fact, there is a strong suggestion that premature rupture of the membranes actually increases the risk of respiratory distress syndrome at a given gestational age.

Single umbilical artery: accurate diagnosis?

OBJECTIVE

We sought to evaluate the accuracy of ultrasonographic, obstetric, and neonatal diagnosis of a single umbilical artery.

STUDY DESIGN

We studied 17,777 consecutive singleton births from women who had undergone ultrasonographic examination at our hospital. A single umbilical artery was confirmed in 37 cases (0.2%) by two clinical methods or by pathologic assessment. Outcome of neonates with a single umbilical artery was compared with the outcome of neonates with either two or three vessel cords.

RESULTS

Ultrasonographic diagnosis had a 65% sensitivity and positive predictive value. Obstetricians and pediatricians failed to diagnose 24% and 16% of the cases, respectively. On average, neonates with a single umbilical artery weighed 320 gm less, were delivered 1 week earlier, and had lower Apgar scores than neonates with three vessel cords (p < 0.01 in each case.)

CONCLUSION

Although early gestational age may account for some cases not diagnosed by ultrasonography, there is a little justification for missing the diagnosis after delivery. Greater emphasis on clinical examination of the umbilical cord is needed to identify neonates at risk of associated malformations.

Ultrasonographic prediction of neonatal survival in extremely low-birth-weight infants

OBJECTIVE

Our purpose was to improve the accuracy of prenatal prognostication by directly correlating obstetric ultrasonographic measurements with neonatal survival.

STUDY DESIGN

We studied 130 singleton live-born infants with birth weights between 500 and 1000 gm and who underwent complete ultrasonographic examinations within 3 days of delivery. Ultrasonographic measurements were evaluated as screening tests for neonatal survival by means of receiver-operator characteristic curves and compared with birth weight and pediatric assessment of gestational age.

RESULTS

Eighty infants survived, and 50 died. Visual inspection of the receiver-operator characteristic curves indicated that biparietal diameter was the best predictor of survival. While correctly identifying all survivors, biparietal diameter predicted nonsurvivors better (p < 0.0001) than did actual birth weight or any other variable.

CONCLUSION

Our findings indicate that using biparietal diameter to determine neonatal prognosis is significantly more reliable than the current practice of using estimated fetal weight. We speculate that biparietal diameter may reflect maturity more accurately because it is less subject to variation in growth.

Amniotic fluid platelet factor 4 and beta-thromboglobulin

Platelet activating factor (PAF), a powerful platelet activator, has been identified in human embryos and fetuses, and may induce fetal lung maturation. The potential effect of PAF on fetal platelets as indicated by release of beta-thromboglobulin (BTG) and platelet factor 4 (PF4) has not been investigated. We measured BTG and PF4 in amniotic fluid from 78 genetic and 35 pulmonary maturity amniocenteses. BTG and PF4 were higher in the genetic amniocentesis samples (p < 0.001 in each case) than in the lung maturity samples. BTG and PF4 did not correlate with the pulmonary maturity parameters as measured by the lecithin to sphingomyelin ratio and phosphatidylglycerol concentration. Our findings suggest a fetal origin of BTG and PF4 in amniotic fluid.

Trends in sonographic fetal organ visualization

In order to assess changes in sonographic visualization over the last 6 years, 7092 second- and third-trimester ultrasound examinations from separate pregnancies in three individual years (1451 in 1985, 3016 in 1988, and 2625 in 1991) were compared. Overall, visualization across all gestational ages improved from 63.9% (1985) to 85.8% (1988) to 87.3% (1991), with the year in which the scan was performed explaining 19.6% of the variance in visualization. Maternal size (as determined by body mass index) remained the major determinant of ultrasound visualization in 1991 (r(2) = 11.2%), with gestational age explaining only 5.2% additional variance. Overall organ visualization was maximal at 21-23 weeks' gestation, with the decline in later gestation primarily accounted for by worsened visualization of fetal extremities and spine. Improved fetal visualization earlier in the second trimester and the advent of embryonic visualization in the first trimester may allow a continuum of prenatal sonographic diagnosis.

Markers for endothelial injury, clotting and platelet activation in preeclampsia

The etiology of disseminated intravascular coagulation (DIC) in preeclampsia is not well understood. We measured plasma levels of fibronectin (FN), which may reflect endothelial cell injury, fibrinopeptide A (FPA), a specific marker of clotting, platelet counts (PLC) and mean platelet volumes (MPV), as well as beta-thromboglobulin (beta TG) and platelet factor 4 (Pf4), products of irreversible platelet activation in 24 preeclamptic patients and 24 controls matched for age, gestational age, labor status, and parity. In preeclampsia, FN and FPA were significantly elevated while PLC were significantly decreased (P less than 0.0001, less than 0.05 and less than 0.01, respectively). beta TG, Pf4, and MPV values did not show significant differences. These findings support the hypothesis that endothelial injury, clotting activation and platelet consumption are increased in preeclampsia. However, the much closer association of preeclampsia with FN levels as compared to FPA, beta TG, Pf4, suggests that endothelial injury is a more basic mechanism of preeclampsia than clotting or platelet activation.