Relationship between fetal pulmonary maturity assessment and neonatal outcome in premature rupture of the membranes at 32-34 weeks' gestation

The absence of fetal pulmonary maturity in patients with preterm premature rupture of the membranes (PPROM) is often considered an indication for conservative management. The purpose of this study was to examine the value of biochemical pulmonary maturity assessment for the prediction of neonatal outcome in patients with PPROM between 32 and 34 weeks' gestation. Pregnancies complicated by PPROM at 32 to 34 weeks' gestation that delivered from January 1995 to May 2000 and had biochemical pulmonary maturity assessment were reviewed. Patients with medical disorders, multiple gestations, fetal growth restriction or structural anomalies, or evidence of intra-amniotic infection were excluded. Neonatal outcome measures were compared between patients with mature and immature pulmonary indices. During this time period, 244 patients with PPROM at 32-34 weeks' gestation were delivered; 78 patients met inclusion criteria (n = 41 patients with mature indices and n = 37 patients with immature indices). There were no cases of perinatal death or sepsis. There was no difference in major neonatal morbidities including need for mechanical ventilation, grade 2 or 3 necrotizing enterocolitis, grade 3 or 4 intraventricular hemorrhage, or seizures. After controlling for confounding factors including gestational age at PPROM and delivery, latency period, group B streptococcus (GBS) vaginal colonization, corticosteroid therapy, neonatal sex, mode of delivery, fetal indications for delivery, and umbilical cord pH, biochemical pulmonary maturity was not predictive of major neonatal morbidity. In our population, biochemical pulmonary maturity status does not appear to be predictive of neonatal morbidity in pregnancies complicated by PPROM at 32-34 weeks' gestation.

[The dry period in preterm birth and premature rupture of the fetal membranes]

It is widely believed that premature rupture of membranes accelerates fetal pulmonary maturity. The purpose of our study was to determine the duration of the latent phase, in the cases of premature rupture of membranes, required to achieve this effect. Retrospective analysis of our database yielded a group of 42 patients, who were delivered between 26 and 34 weeks gestation. The results of this study suggest that pulmonary maturation continues but is not accelerated after premature rupture of membranes. Delaying delivery for more than 72 hours after rupture of membranes is more likely to result in chorioamnionitis than accelerated pulmonary maturation.

[The corticosteroid therapy of premature rupture of the fetal membranes]

Antenatal corticosteroids are now administered for the purpose of hastening maturation of the preterm infant's organs and tissues, thus reducing neonatal mortality and the incidence of respiratory distress syndrome (RDS). Our purpose was to determine the efficacy of maternal corticosteroid therapy on fetal maturation in cases with preterm premature rupture of the membranes. The rates of RDS and survival in low birth weight infants treated with corticosteroids is influenced by the duration of the premature rupture of the membranes and the duration of the corticosteroid therapy, as well as by the gestational age.

Antepartum surveillance in preterm rupture of membranes

The objective of this presentation is to describe noninvasive techniques of antepartum fetal assessment which allow the differentiation of fetuses who will benefit from remaining in-utero versus those who are at risk for intraamniotic infection and will benefit from your prompt delivery. The literature is reviewed in regard to the fetal biophysical profile, the effect of premature rupture of membranes (PROM), the usefulness of individual biophysical component in predicting intraamniotic infection (amniotic fluid volume, non-stress testing), the use of the fetal biophysical profile in improving pregnancy outcome, the relationships among umbilical artery velocimetry, fetal biophysical profile and intraamniotic infection and the mechanisms by which infection diminishes fetal biophysical activities in PROM. After reviewing our own as well as the published experience with the use of fetal biophysical assessment in patients with PROM, the following conclusions are suggested: a) most studies have shown strong correlation between abnormal biophysical assessment and infection outcome (maternal and/or neonatal infection) as well as intraamniotic infection, if there is frequent (i.e. daily) testing; and b) fetal biophysical tests (profiles, NSTs, amniotic fluid volume determinations) are quite reliable in predicting the well fetus who can safely remain in-utero and also the fetus who is at high risk for developing neonatal sepsis. A protocol for management of preterm PROM will be outlined based upon frequent (daily) fetal biophysical assessment. Although there are no controlled randomized trials to support that pregnancy outcome is improved by the use of frequent biophysical assessment, non-randomized studies as well as studies with historic controls suggest that the use of frequent biophysical assessment is beneficial in managing patients with PROM.

Effect of induced oligohydramnios on fetal lung development

To investigate the impact of oligohydramnios on fetal growth, development, and lung function, amniotic fluid was shunted from alternate gestational sacs into the maternal peritoneal cavity at 23 days' gestation in the fetal rabbit. Uninstrumented fetuses served as controls. Oligohydramnios was confirmed at the time of planned cesarean delivery on either day 26 or 28. Fetuses subjected to prolonged oligohydramnios had significantly decreased body weight at 26 (p = 0.002) and 28 days (p = 0.007). Similarly, lung weight was decreased at 26 (p = 0.02) and 28 days (p = 0.005). There was a trend toward decreased maximum lung volume for instrumented fetuses at 28 days (p = 0.07). Deflation limbs of the pressure-volume curves revealed significantly increased air trapping for instrumented fetuses at 28 days. These studies suggest not only a detrimental effect of oligohydramnios on fetal body and lung weight but also a beneficial effect of premature rupture of membranes on fetal lung function. Analysis of phospholipid and histologic changes is currently under way.

Second trimester oligohydramnios, a predictor of poor fetal outcome

Twelve cases of severe second trimester oligohydramnios are reported. The outcome of these pregnancies was uniformly poor, with no survivors in the present series. Four patients had therapeutic abortions, one woman had spontaneous labor at 22 weeks' gestation, and seven patients continued to viability. Of these, five patients had severe renal abnormalities incompatible with life. Two infants died at, or shortly after, birth from severe intrauterine growth retardation (IUGR), one of which had a triploid karyotype. Review of the literature shows a similar poor outcome for pregnancies with severe oligohydramnios in the second trimester.