Twin pregnancy and severe maternal mental illness: a Canadian population-based cohort study

Abstract

Objective: To quantity the short-and long-term risks of severe maternal mental illness arising after a twin vs. singleton birth.Methods: This propensity-score weighted population-based retrospective cohort study comprised primiparous Canadian women aged 15-50 years. We compared 15,024 twin livebirths to 796,804 singletons livebirths, from 2003-2019. The primary composite outcome was a psychiatric emergency department visit, hospitalization, self-harm or suicide eventboth in the first year postpartum, and from 1 year postpartum up to 17 years post-delivery. Results:In the first year postpartum, after weighting, the rate of composite outcome events was 10.5 vs. 8.7 per 1000 person-years among twin and singleton births respectively (HR 1.21, 95% CI 1.07-1.47). Starting from 1 year postpartum, the corresponding rates were 5.9 vs. 6.1 per 1000 person-years (HR 0.96, 95% CI 0.89-1.04). Conclusions:Women with a twin birth may experience more severe adverse mental health within 1-year postpartum, but not in the long-term.I would like to thank everyone who assisted me with my studies and contributed to this thesis project. Specifically, I would like to thank my supervisor, Dr. Simone Vigod for her enthusiasm in working with an ObGyn resident, and her assistance, support, and encouragement throughout the process. I would also like to thank my thesis committee consisting of Dr. Hilary Brown, Dr. Kellie Murphy, and Dr. Joel Ray for their engagement with this project and ongoing support and positive feedback, as well as Kinwah Fung for her data support at ICES. As well, I would like to thank the University of Toronto Department of Obstetrics and Gynecology, and specifically Dr. Michèle Farrugia and Dr. John Kingdom for their logistical and financial support which allowed me to complete this degree during my residency. Finally, I would like to thank my friends and family for supporting me through the challenges and celebrating my successes.