The Association of Twin Chorionicity with Maternal Outcomes.

Objective: Our objective was to investigate the association between maternal outcomes and twin chorionicity in a large, contemporary obstetric population.
Study Design: Retrospective cohort study was conducted at a single, large tertiary care center. Prenatal and inpatient records for all individuals with twin gestations were reviewed from 2000 to 2016. Patients with monoamniotic twins, higher-order multiples reduced to twins, multiple sets of twins in the study period, or undetermined chorionicity were excluded. Patients with monochorionic twins were compared with those with dichorionic twins. The co-primary outcomes were gestational diabetes mellitus and hypertensive disorders of pregnancy. Secondary outcomes included cesarean delivery, preterm delivery, postpartum hemorrhage, and other maternal outcomes. Bivariate and multivariate analyses were performed to assess associations of chorionicity with maternal outcomes.
Results: Of the 2,979 patients eligible for inclusion, 2,627 (88.2%) had dichorionic twin gestations and 352 (11.8%) had monochorionic twin gestations. Patients with monochorionic twins were less likely to self-identify as non-Hispanic White and to have conceived via assisted reproductive technology but were more likely to be publicly insured, multiparous and have prenatal care with a maternal-fetal medicine provider. Neither gestational diabetes mellitus (6.8% monochorionic vs. 6.2% dichorionic, p  = 0.74; adjusted odds ratio [OR] 1.06, 95% confidence interval (CI) 0.60-1.86) nor hypertensive disorders of pregnancy (21.9% monochorionic vs. 26.3% dichorionic, p  = 0.09; adjusted OR 0.99, 95% CI, 0.71-1.38) differed by chorionicity. Of the secondary maternal outcomes, patients with monochorionic twins experienced a lower frequency of cesarean delivery (46.0 vs. 61.8%, p  < 0.001), which persisted after multivariate analyses (adjusted OR 0.60, 95% CI 0.46-0.80). There were no differences in preterm delivery, preterm premature rupture of membranes, hemorrhage, hysterectomy, or intrahepatic cholestasis of pregnancy.
Conclusion: The odds of gestational diabetes mellitus and hypertensive disorders of pregnancy do not appear to differ by twin chorionicity.
Key Points: · Hypertensive disorders of pregnancy do not differ by twin chorionicity.. · Gestational diabetes mellitus does not differ by twin chorionicity.. · Maternal outcomes are similar for individuals with monochorionic and dichorionic twin gestations..
Competing Interests: None declared.
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