Pre-eclampsia in a first pregnancy and subsequent pregnancy outcomes: a nationwide cohort study.

BACKGROUND: For women whose first pregnancy was complicated by pre-eclampsia (PE), particularly if severe and requiring early birth, the risk of recurrence and maternal and neonatal outcomes at subsequent birth are important considerations. METHODS: In this observational cohort study, all primiparous women who gave birth in Denmark between 1997 and 2016 were identified using nationwide registries. Women were stratified by whether they developed PE and followed from date of birth until subsequent birth, emigration, death or end of study (December 2016). The cumulative incidences of subsequent birth among women with versus without PE were assessed using the Aalen-Johansen estimator. Subsequent outcomes including PE recurrence and maternal and neonatal morbidity and mortality were also examined. Factors associated with subsequent birth and recurrent PE were examined using multivariable Cox regression models. RESULTS: Among 510 615 primiparous women with singleton pregnancies, 21 683 (4.2%) developed PE, with 1819 (0.4%) being early-onset PE (birth <34 weeks). Women with PE had a lower subsequent birth rate (57.4%) compared with women without PE (61.2%), and it was considerably lower among women with early-onset PE (49.4%). Among women with PE who had a subsequent birth, the overall recurrence rate of PE was 15.8% and higher among those with early-onset PE (31.5%). The gestational age increased with a median of 3 days (IQR -5 to 14) overall and 50 days (IQR 35-67) among those with early-onset PE. Moreover, neonatal and maternal morbidity and mortality were substantially improved in a subsequent pregnancy. CONCLUSIONS: Primiparous women with PE have a significantly lower rate of a subsequent birth than women without PE, yet the absolute difference was modest. Although the overall risk of recurrent PE is 1 in 6, maternal and neonatal morbidity and mortality at subsequent birth are substantially improved.