Effectiveness of antenatal steroids in obstetric subgroups

To determine the effectiveness of antenatal steroids in the reduction of neonatal morbidity and mortality in obstetric subgroups of preterm labor with intact membranes, preterm premature rupture of membranes (PROM), and pregnancy-associated hypertension. The secondary objective was to determine the effect of antenatal steroids in appropriate for gestational age (AGA) and growth-restricted neonates.

We studied the neonatal outcomes for all women who delivered infants weighing 1750 g or less at birth between January 1990 and July 1997 at our institution. The study population was divided primarily into three clinical groups: preterm labor with intact membranes, PROM, and pregnancy-associated hypertension. Secondarily, the total population was divided based on birth weight and gestational age into AGA and growth-restricted neonates. Within each obstetric subgroup, neonates exposed to antenatal steroids were compared with unexposed neonates for respiratory distress syndrome (RDS), intraventricular hemorrhage and periventricular leukomalacia, the incidence of major brain lesions, necrotizing enterocolitis, proved neonatal sepsis, patent ductus arteriosus, and neonatal death. The subgroups were also compared for gestational age at delivery, birth weight, birth weight percentile, Apgar scores, postnatal surfactant exposure, and clinical and histologic chorioamnionitis. Descriptive statistics, Student t test, chi2, Fisher exact test, and logistic regression were used for analysis.

A total of 1148 neonates weighing 1750 g or less were delivered during the study period. There were 447 and 410 neonates delivered after preterm labor with intact membranes and PROM, respectively, and 245 neonates born to mothers with pregnancy-associated hypertension. Nine hundred twenty-eight neonates were AGA and the remaining 220 neonates were growth restricted. Antenatal steroids significantly decreased the incidence of RDS, the incidence and severity of intraventricular hemorrhage and periventricular leukomalacia, necrotizing enterocolitis, and neonatal mortality in preterm labor with intact membranes. In the presence of PROM, it significantly decreased the incidence and severity of intraventricular hemorrhage and periventricular leukomalacia and decreased neonatal mortality, with no apparent effect on the incidence of RDS. Antenatal steroids did not show any beneficial effect in pregnancy-associated hypertension and fetal growth restriction (FGR). Additionally, a significant increase was observed in the incidence of proved neonatal sepsis when antenatal steroids were used in pregnancy-associated hypertension.

The effectiveness of antenatal steroids varies with the obstetric population studied. Antenatal steroids significantly decreased the incidence of major neonatal morbidity and mortality in the AGA preterm neonate delivered after preterm labor with intact membranes. Antenatal steroids did not show any benefit in cases of pregnancy associated with maternal hypertension or FGR. Its effect in the presence of PROM is limited to a significant reduction in the incidence and severity of intraventricular hemorrhage and periventricular leukomalacia and in neonatal death.