Twin Birth and Hemolysis, Elevated Liver Enzymes, and Low Platelets (HELLP) Syndrome: A Population-Based Study.

OBJECTIVES

Although twin pregnancies are known to have higher rates of preeclampsia, the association between twin pregnancy and Hemolysis, Elevated Liver Enzymes, and Low Platelet Count (HELLP) syndrome has not been adequately studied. We assessed the association between twin pregnancy and HELLP syndrome, and also examined gestational age-specific rates of HELLP syndrome in twin and singleton pregnancies.

METHODS

We conducted a retrospective cohort study of women with singleton or twin live births or stillbirths between 200 and 436 weeks gestation in British Columbia, Canada, from 2008/09 to 2019/20. Data on the demographic and clinical characteristics were obtained from the British Columbia Perinatal Database Registry. Logistic regression was used to estimate adjusted odds ratios and 95% CIs, adjusted for maternal age, body mass index, smoking, and other potential confounders.

RESULTS

Among 524 236 women (515 953 singleton and 8283 twin pregnancies), 1510 were diagnosed with HELLP syndrome (2.9 per 1000 women). HELLP syndrome occurred in 181 twin pregnancies (21.9 per 1000 women), while 1329 cases occurred in singleton pregnancies (2.6 per 1000 women) (rate ratio 8.5 [95% CI 7.3-9.9]). The adjusted odds ratio for the associations between HELLP syndrome and twin versus singleton pregnancies was 7.1 (CI 6.0-8.5). In twin pregnancies, the incidence of HELLP syndrome increased markedly from 260 to 286 weeks gestation until 370 to 396 weeks. In contrast, the incidence of HELLP syndrome increased more gradually from 230 to 406 weeks gestation in singleton pregnancies.

CONCLUSIONS

Twin pregnancy is strongly associated with HELLP syndrome. HELLP syndrome risk in twin pregnancies increases markedly from 260 weeks gestation onwards.