Pregnancy-induced hypertension: recurrence rate in second pregnancies

Abstract

Objective: The purpose of this study was to estimate the rate of recurrence of pregnancy-induced hypertension in an Australian population.

Design: Case records of women with hypertension during pregnancy who were delivered at our hospital during a two-year period were examined retrospectively. Those who had pregnancy-induced hypertension and records of subsequent pregnancies at our hospital were examined for recurrence of proteinuric or non-proteinuric pregnancy-induced hypertension in their second pregnancy.

Setting: A Sydney teaching hospital with approximately 2500 obstetric deliveries per year.

Participants: Pregnancy-induced hypertension was defined as diastolic blood pressure above 90 mmHg after 20 weeks' gestation in a nullipara who had normal blood pressure before 16 weeks' gestation, with no known history of hypertension or renal disease and whose blood pressure returned to normal postpartum. Case records of 610 women were examined; 236 had records of a second pregnancy at our hospital and of these 140 had pregnancy-induced hypertension.

Measurement and main results: Of these 140 women 50% had a normotensive second pregnancy (95% CI, 42%-58%), 47% again developed pregnancy-induced hypertension (95% CI, 39%-55%) and 3% (95% CI, 0%-6%) had developed chronic, probably essential, hypertension before their second pregnancy. Proteinuric pregnancy-induced hypertension occurred in 14% of first but only 4.5% of second pregnancies (chi 2(1) = 4.711, df = 1, P less than 0.05).

Conclusions: Although these data are limited by retrospective gathering, it is clear that there is a high recurrence rate of pregnancy-induced hypertension in Australia. However, the risk of having proteinuric pregnancy-induced hypertension, a more severe form of this disorder, diminishes in a second pregnancy.