Increased preeclampsia in mothers delivering very low-birth-weight infants between 1994 and 2006

We sought to determine if there has been any change in the proportion of mothers with preeclampsia in a sample of very low-birth-weight (VLBW) infants over time. We performed a retrospective cohort study. Study sample included infants with birth weights 1500 g or less cared for from July 1994 to July 2006 (n = 2045) from a single level 3 neonatal intensive care unit in Delaware. The main outcome examined was the occurrence of maternal preeclampsia over the study time. The proportion of mothers with preeclampsia delivering VLBW infants increased over time. After controlling for potential confounding variables, the odds of maternal preeclampsia were increased (1.3, 95% confidence interval 1.2 to 1.5) in infants born between 2003 and 2006 compared with those born between 1994 and 1997. In our population of VLBW infants, the proportion of mothers with the diagnosis of preeclampsia increased over time. From our investigation, we cannot determine if the increase in the proportion of mothers with preeclampsia is related to a true increase in the disease, changes in diagnostic surveillance, or other factors.