Maternal risk factors and adverse birth outcomes associated with HELLP syndrome: a population-based study

BJOG. 2020 Sep;127(10):1189-1198. doi: 10.1111/1471-0528.16225. Epub 2020 Apr 13.


Objectives: We assessed the incidence, risk factors and adverse birth outcomes associated with elevated liver enzymes and low platelets (HELLP) syndrome.

Design: A retrospective population-based cohort study.

Setting: Canada (excluding Quebec), 2012/2013-2015/2016.

Population: Mothers with a singleton hospital live birth or stillbirth at ≥24 weeks' gestation (n = 1 078 323).

Methods: HELLP syndrome was identified using ICD-10-CA diagnostic code from delivery hospitalisation 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.

Main outcome measures: Adverse maternal (e.g. eclampsia) and fetal/neonatal outcomes (e.g. intraventricular haemorrhage, perinatal death).

Results: The incidence of HELLP syndrome was 2.5 per 1000 singleton deliveries (n = 2663). 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 the syndrome had a 10-fold higher maternal mortality (95% CI 1.6-84.3) and elevated severe maternal morbidity (9.6 versus 121.7 per 1000; AOR 12.5, 95% CI 11.1-14.1); and higher perinatal mortality (4.3 versus 21.0 per 1000; AOR 4.5, 95% CI 3.5-5.9) and perinatal mortality/severe neonatal morbidity (21.2 versus 202.4 per 1000; AOR 10.7, 95% CI 9.7-11.8).

Conclusion: 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.

Tweetable abstract: HELLP syndrome is associated with higher maternal death rate, and substantially higher severe maternal and neonatal morbidity, and perinatal mortality.

Keywords: HELLP syndrome; perinatal death; severe maternal morbidity; severe neonatal morbidity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Canada / epidemiology
  • Case-Control Studies
  • Databases, Factual
  • Female
  • HELLP Syndrome / mortality*
  • Humans
  • Infant, Newborn
  • Infant, Newborn, Diseases / epidemiology*
  • Middle Aged
  • Pregnancy
  • Retrospective Studies
  • Risk Factors
  • Stillbirth / epidemiology*
  • Young Adult