The purpose of this retrospective cohort study was to: (1) compare IVH rates amongst inborn and outborn LBW infants and (2) determine obstetrical factors associated with outborn births. This was a retrospective cohort study comparing LBW infants delivered at a Level III center (IB) to those LBW infants delivered at referring Level I and II centers (OB). All patients were<32 weeks GA and between 500-1500 grams. The study time period was 1995-96. A mother was considered nontransferable if she presented in preterm labor≥4 cm dilated or with active bleeding. Univariate analyses determined differences between IB and OB infants. Regression analysis determined association between IB/OB status and IVH while controlling for confounders. Gestational age was similar amongst IB and OB infants (p=0.8). The Table summarizes results: Odds ratio for severe IVH/PVL was 4.2 (95% CI 2.6-5.8) in OB when compared to IB after controlling for GA, antenatal steroid exposure, birth route, and transferable status. Seventy-seven percent (20/26) of OB infants were born to nontransferable mothers. Sixty percent (13/20) were ≥4 cm dilated and in active labor, 18%(6/20) were actively bleeding, and one had severe varicella pneumonia.

Table 1 No caption available.
Full size table

Conclusion: Severe IVH is associated with OB status in the Milwaukee area. Since most OB are born to mothers who present in a nontransferable state, reduction of severe IVH in LBW infants will require education of both delivering physicians and pregnant mothers.