Pregnancy-induced hypertension and reduced intraventricular hemorrhage in preterm infants.

Increasing evidence suggests that the incidence of periventricular intraventricular hemorrhage (PV-IVH) is lower in infants born to mothers with pregnancy-induced hypertension (PIH). The mechanism or mechanisms accounting for this reduction remain unclear but may be related to PIH itself, medications used to treat the mother (e.g., magnesium sulfate), or to obstetrical management. In this retrospective analysis, we determined the incidence of PV-IVH in singleton preterm infants weighing less than 1,500 gm born to mothers with PIH who were also administered magnesium sulfate. Between January 1988 and December 1994, 254 singleton infants born to mothers with PIH and 1,083 born to mothers without PIH were studied. PV-IVH developed in 360 (26.9%) of the 1,337 infants; 977 (74.1%) infants did not exhibit PV-IVH. The incidence of total as well as severe PV-IVH was lower in infants born to mothers with PIH than in those without PIH [i.e., 16% vs 30% (total) and 8.2% vs 14.5% (severe), P < .001] with an odds ratio (OR) estimate of 0.43 [95% confidence interval (CI) 0.30, 0.61]. Infants born to mothers with PIH weighed more, (1,152 +/- 250 gm vs 1,058 +/- 283 gm, P < .001) and were more mature (30.1 +/- 2.9 vs 27.7 +/- 31 weeks, P < .001) than infants born to mothers without PIH. These infants were also less likely to be exposed to labor (57% vs 93%), to be delivered by cesarean section (81% vs 35%), and to require intubation (49% vs 58%), but more likely to exhibit respiratory distress syndrome (RDS) (47% vs 38%, P < .01). By logistic regression analysis, after seven variables (i.e., PIH, gestational age, and birthweight, both modeled as cubic polynomials; labor; intubation; RDS; and race) were included in the analytic model, PIH remained a significant predictor of IVH: P = .006, OR = 0.54 (95% CI 0.349, 0.847). These data indicate a significantly lower incidence of PV-IVH of approximately 50% in infants born to mothers with PIH as compared with the incidence in infants born to mothers without PIH, despite their higher incidence of RDS. The reduction in PV-IVH may be directly related to the PIH; however, the independent role of antenatal magnesium sulfate administration requires further study.