Recurrent preterm delivery following twin versus singleton preterm delivery: A retrospective cohort

Objective: The main risk factor for preterm delivery (PTD; <37 gestational weeks) is having a history of PTD. The aim of this research was to compare the risk for recurrent PTD following twin versus singleton gestation PTD.Methods: A retrospective population-based cohort study was performed, including all women who had two consecutive pregnancies, the first of which ended with PTD. The incidence of PTD recurrence was compared between women with PTD in twin versus singleton gestation. Multivariable logistic models were used to study the association between twinning status and PTD recurrence, and specifically by gestational age of the first PTD, inter-pregnancy interval (IPI), and mode of conception.Results: The study population included 15 590 women, of whom 1680 (10.8%) had twins in their index pregnancy and 13 910 (89.2%) had singletons. The incidence of recurrent PTD was 10.5% (n = 177) following twin PTD versus 21.9% (n = 3044) following singleton PTD (adjusted odds ratio = 0.50, 95% confidence interval 0.32-0.76, while controlling for confounding variables). The results were consistent while stratifying by IPI, gestational age of the first PTD, or mode of conception.Conclusions: Women with PTD in twin gestations are at lower risk for recurrent PTD compared with women with singleton PTD.