Pregnancy Outcomes in Women with Preeclampsia Superimposed on Chronic Hypertension with and without Severe Features.

 The American Congress of Obstetricians and Gynecologists (ACOG) task force on hypertension in pregnancy introduced a new definition of superimposed preeclampsia (SIP) adding severe features (SF) as new criteria to define severe disease. They also recommended that those with SIP be delivered ≥ 37 weeks, whereas those with SF be delivered ≤ 34 weeks. Our aim was to investigate the validity of this new definition by comparing adverse pregnancy outcomes in SIP with (SIP-SF) and without SF (SIP).  Women with chronic hypertension (CHTN) enrolled in a multicenter trial were studied. SIP was reclassified according to the new definition to SIP and SIP-SF (persistent systolic blood pressure [BP] > 160 or diastolic BP > 110, platelets < 100 K, liver function tests > 70, creatinine > 1.1, or persistent central nervous system/abdominal symptoms). Composite adverse outcomes including rates of indicated preterm birth, abruptio placentae, postpartum hemorrhage, and maternal death were compared by chi-square. Adjustment was done with a multivariate logistic-regression analysis and all statistical tests were two-sided.  A total of 216 women (28%) out of 774 with CHTN developed SIP, 87 (11%) had SIP-SF, and 129 (17%) didn't have SF. Baseline characteristics including maternal age, baseline BP, and assignment to low-dose aspirin were similar between groups. Using univariate analysis, the composite adverse outcome was higher among the SIP-SF group ( = 0.04), as well as indicated preterm birth ( = 0.02), cesarean section ( = 0.02), and SGA ( = 0.02). After adjustment, composite adverse outcomes were not significantly different between groups. The rate of SGA, however, was higher among SIP-SF (adjusted odds ratio: 3.12,  = 0.02).  The rate of SIP-SF in this study was 11% of all women with CHTN. Surprisingly, pregnancy outcomes were not significantly different in those with and without SF. We suggest a prospective observational study to determine the optimal timing for delivery in those with SIP using new ACOG diagnostic criteria.