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.

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

Benefits of maternal corticosteroid therapy in infants weighing

OBJECTIVE: The aim of the study was to determine the effects of antenatal maternal corticosteroid treatment on selected neonatal outcomes in infants weighing

Indicated versus spontaneous preterm delivery: An evaluation of neonatal morbidity among infants weighing

OBJECTIVE: The aim of the study was to determine whether infants weighing 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

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 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.

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 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.

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.

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.

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.

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.

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.

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.