Impact of pre-eclampsia in extremely premature infants: Population-based study.

BACKGROUND: The relationship between chorioamnionitis (CAM) and neonatal mortality has been extensively investigated, but that of maternal pre-eclampsia and neonatal mortality is unclear. We investigated neonatal mortality and morbidity of maternal pre-eclampsia and clinical CAM in extremely premature infants using data from a population-based cohort study. METHODS: We retrospectively analyzed data obtained from the Neonatal Research Network in Japan, a population-based cohort study (n = 18 900) conducted to clarify the clinical characteristics and morbidity of very low-birthweight infants. Patients were divided into four diagnosis-based groups for comparative analysis: sole pre-eclampsia; sole clinical CAM; concurrent pre-eclampsia and clinical CAM; and non-diagnosis (of pre-eclampsia and clinical CAM). RESULTS: Mortality was higher in the pre-eclampsia groups compared with the groups without (18.3%, 84/459 vs 14.0%, 567/4059; OR, 1.38; 95%CI: 1.07-1.78). In contrast, mortality was not affected by presence of clinical CAM (with, 13.7% 182/1328 vs without, 15.0% 469/3190; OR, 0.92; 95%CI: 0.77-1.11). With regard to small for gestational age, the mortality rate increased by two-three-fold as gestational week decreased. The complication survival rate in the whole group was 35% (1135/3218). CONCLUSIONS: Maternal pre-eclampsia is associated with poor prognosis in extremely premature infants. We also need to deliberate on the trade-off between the advantages of early rescue from pre-eclampsia and risk of prematurity.