Maternal risk factors and adverse birth outcomes associated with HELLP syndrome: a population-based study.
We assessed the incidence, risk factors and adverse birth outcomes associated with elevated liver enzymes and low platelets (HELLP) syndrome.A retrospective population-based cohort study.Canada (excluding Quebec), 2012/13-2015/16.Mothers with a singleton hospital live birth or stillbirth at ≥24 weeks gestation (N=1,078,323).HELLP syndrome was identified using ICD-10-CA diagnostic code from delivery hospitalization data. We used logistic regression to identify independent risk factors for HELLP syndrome by obtaining adjusted odds ratios (AOR) and 95% confidence intervals (CI), and to assess the associations with adverse outcomes.Adverse maternal (e.g., eclampsia) and fetal/neonatal outcomes (e.g., intraventricular hemorrhage, perinatal death).The incidence of HELLP syndrome was 2.5 per 1,000 singleton deliveries (n=2,663). Risk factors included: age ≥35 years, rural residence, nulliparity, parity ≥4, pre-pregnancy and gestational hypertension and diabetes, assisted reproduction, chronic cardiac conditions, systemic lupus erythematosus, obesity, chronic hepatic conditions, placental disorders (e.g., fetomaternal transfusion), and congenital anomalies; PROM and age <25 years were inversely associated with HELLP syndrome (p-values <0.05). Women with syndrome had a 10-fold higher maternal mortality (95% CI 1.6-84.3) and elevated severe maternal morbidity (9.6 vs. 121.7 per 1,000; AOR=12.5, 95% CI 11.1-14.1); and higher perinatal mortality (4.3 vs. 21.0 per 1,000; AOR=4.5, 95%CI 3.5-5.9) and perinatal mortality/severe neonatal morbidity (21.2 vs 202.4 per 1,000; AOR=10.7, 95% CI 9.7-11.8).HELLP syndrome is associated with specific pre-pregnancy and pregnancy risk factors, higher rates of maternal death, and substantially higher severe maternal morbidity, perinatal mortality and severe neonatal morbidity.