Risks of hypertensive disorders in the second pregnancy.

This study examined the incidence of and risk factors for recurrent and newly developed hypertensive disorders in the second pregnancy. We analysed data on 1641 women who had both the first and second pregnancies in the Collaborative Perinatal Project, a large prospective cohort study at 12 hospitals in the US. Nineteen per cent [95% CI 14%, 24%] of women who had gestational hypertension in the first pregnancy, 32% [95% CI 17%, 48%] of those with pre-eclampsia and 46% [95% CI 32%, 60%] of patients with gestational hypertension or pre-eclampsia superimposed on chronic hypertension, had recurrent hypertensive disorders in the second pregnancy. Risk factors for recurrence included history of chronic hypertension and thromboembolism, early onset of hypertension in the first pregnancy or persistent hypertension after 5 weeks postpartum and high baseline blood pressure in the second pregnancy. Women with a normotensive first pregnancy but a severe small-for-gestational-age birth had twice the risk of developing hypertension in the second pregnancy (RR = 2.1, 95% CI, 1.1, 4.0). In summary, hypertensive disorders have a 20--50% recurrence rate in the second pregnancy. The earlier the onset of hypertension in the first pregnancy, the higher the overall recurrence rate. Intrauterine growth restriction of the first birth is an independent risk factor for hypertension in the second pregnancy.