Objective: To evaluate the association of intertwin membrane separation and pregnancy outcome.
Methods: This is a retrospective cohort study of women with dichorionic twins who were diagnosed with spontaneous intertwin membrane separation between 2004 and 2013 at a large tertiary care maternity hospital. Control participants were selected as the next two sets of dichorionic twins that delivered at the study institution after a case participant delivered and that did not have an intrauterine procedure. Maternal, fetal, and delivery characteristics were compared using Wilcoxon rank-sum tests. Logistic regressions were used to assess the association of membrane separation and preterm delivery.
Results: Among the 27 cases of spontaneous intertwin membrane separation, the median gestational age at diagnosis was 28 weeks (interquartile range 25.5-28.8) and the median gestational age at delivery was 37 weeks (interquartile range 35.3-37.0). The rate of preterm delivery, our primary outcome, was 48% for the case group and 76% for the control group (odds ratio [OR] 0.29, P=.01). The rate of spontaneous preterm delivery was also lower for the case group (19% compared with 44%; OR 0.25, P=.26) as was the rate of neonatal intensive care unit admission (37% compared with 61%; OR 0.37, P=.04).
Conclusion: Our retrospective cohort study demonstrates that intertwin membrane separation is not associated with adverse outcomes in dichorionic twin pregnancies. Thus, it is reasonable to manage these pregnancies expectantly.
Level of evidence: II.