Comparison of risk factors and perinatal outcomes in early onset and late onset preeclampsia: A cohort based study in Reunion Island.

Clinical differences, maternal risk factors and pregnancy outcomes of deliveries complicated by early- (delivery<34 weeks) and late-onset (delivery≥34 weeks) preeclampsia were studied in a cohort of women in Reunion Island during 15 years (period 2001-2015; N=62,230 pregnancies). The overall preeclampsia rate in singleton pregnancies was 2.37%. Early- and late-onset preeclampsia rates were 0.75% and 1.5% respectively, and the trend for each type of disease was stable over time. In both form of preeclampsia, smoking during pregnancy was a protective factor and associated risk factors were: older age, primiparity, pre-existing diabetes, chronic hypertension, higher pre-pregnancy body mass index and obesity, infertility treatment, history of renal disease and hypercholesterolemia (all p<0.05). The rate of caesarean section, medically-induced delivery and impaired foetal and neonatal outcomes were significantly higher in preeclamptic women (all p<0.0001). When comparing early- versus late-onset preeclampsia, the only difference was the older maternal age in primiparae with early-onset preeclampsia (p=0.02), and the two groups of preeclamptic women were similar in terms of maternal risk factors, with the exception of higher rates of chronic hypertension in early-onset preeclampsia (p=0.02). Foetal and neonatal outcomes were evaluated after adjustment for gestational age at delivery and no difference was detected between early- and late-onset preeclamptic women. These analyses failed to identify a specific phenotype of preeclampsia in terms of predisposition or pre-existing risk factors for one form or another. Gestational age at delivery was the most important predictor for offspring outcome.