Objectives: To compare the impact of pregnancy-induced hypertension (PIH) and chronic hypertension (CHH) on pregnancy outcome.
Study design: Retrospective study of data from a large perinatal data base with 109,428 consecutive deliveries from 1982 to 1987.
Results: Among 109,428 women who delivered during the study period, 8019 (7.3%) were hypertensive. The hypertensive group included 5971 (74.5%) with PIH and 2048 (25.5%) with CHH. Hypertension was associated with a significantly higher risk for adverse pregnancy outcome. Compared with PIH, CHH was more likely to result in an adverse outcome as shown by increased odds ratio (OR) for fetal death (OR, 1.9 for PIH, 2.9 for CHH), prematurity (OR 1.6 for PIH, 1.8 for CHH), and intrauterine growth retardation (OR 2.8 for PIH, 3.7 for CHH). Chronic hypertension was associated with a 184 gm reduction in birth weight compared with 168 gm reduction with PIH. Mothers with CHH were more likely to be black (CHH, 50.1%; PIH, 40.2%), receive public assistance (CHH, 41.6%; PIH, 34.5%), and have no prenatal care (CHH, 3.2%; PIH 2.1%).
Conclusions: In this study population, hypertension during pregnancy was associated with significantly increased morbidity and mortality rates. Women with chronic hypertension are at greater risk for adverse outcome than those with pregnancy-induced hypertension.