Introduction: Elevated risk of adverse fetal/infant outcomes associated with twin pregnancy are well known, while severe maternal morbidity has been understudied. In this study we quantified severe maternal morbidity and mortality associated with twin vs singleton pregnancy.
Methods: We carried out a population-based retrospective cohort study of all hospital singleton and twin births at ≥20 weeks’ gestation in Canada (excluding Quebec) between 2004 and 2017 (N=3,924,873). We used data from the Canadian Institute for Health Information, which contains information on all hospital separation including maternal characteristics and delivery details. Rates of severe maternal morbidity (SMM) and mortality associated with twin pregnancy were quantified. Adjusted odds ratios (AOR) and 95% confidence intervals (CI) were estimated using logistic regression after adjusting for maternal age, parity, chronic hypertension and diabetes, previous caesarean, and assisted conception.
Results: Overall, 54,438 twin deliveries (1.4%) occurred between 2004 and 2017. The rate of composite SMM/maternal death was 33.8 per 1,000 twin deliveries vs 9.69 per 1,000 singleton deliveries (rate ratio 3.49, 95% CI 2.52-4.66; AOR 2.80, 95% CI 2.65-2.97). Women with twin delivery had significantly increased rates of severe preeclampsia, eclampsia or HELLP syndrome (AOR 4.26, 3.86-4.70), severe hemorrhage (AOR 2.78, 2.47-3.13), ICU admission (AOR 2.81, 2.29-3.45), severe cardiac conditions (AOR 4.25, 3.52-5.14), acute renal failure (AOR 4.68, 3.71-5.91) and other morbidity (Table 2). Maternal mortality was as 5.51 per 100,000 twin pregnancies compared with 3.42 per 100,000 singleton pregnancies (rate ratio 1.43, 95% CI 0.45-3.45). The median length of hospital stay for women with twins vs singletons was 4 days versus 3 days, while the frequency of prolonged hospital stay (≥ 7 days) was 11.6% versus 1.56%, respectively.
Conclusion: Compared with women with singletons, women with twin pregnancy are at increased risk of severe maternal morbidity and delivery should be planned accordingly.
Amelie Boutin– Post-Doctoral Fellow, University of British Columbia
Giulia Muraca– Post-Doctoral Fellow, Karolinska Institutet
Neda Razaz– Postdoctoral Fellow, Karolinska Institutet
KS Joseph– Professor, Department of Obstetrics and Gynaecology, Children's & Women's Health Centre of British Columbia; University of British Columbia; Women's Health Research Institute; BC Children's Hospital Research Institute
Sarka Lisonkova– Assistant Professor, University of British Columbia
Yasser Sabr– University of British Columbia