Obstetric events and risk of periventricular hemorrhage in premature infants.

The relationships between selected obstetric factors and the occurrence of periventricular-intraventricular hemorrhage (PIH) was studied in a group of 77 infants weighing 1,200 g or less at birth. The diagnosis of PIH was made using ultrasonography or at autopsy in 42 (55%) of these infants. Univariate associations between PIH and gestational age (less than 30 weeks), duration of labor (greater than or equal to six hours), and vaginal delivery were found. Multivariate analysis, however, did not substantiate an association between PIH and any single obstetric factor. Log-linear analysis of multiway frequency tables showed significant second-order associations of PIH with gestational age and presentation during delivery and with duration of labor and presentation. A model for the risk of PIH based on gestational age, presentation, and duration of labor was derived using stepwise logistic regression. This model correctly predicted PIH in 70% (55) of the infants. Although obstetric factors may have a role in the pathogenesis of PIH, the interactions among factors, rather than single factors alone, are important.