The placental component and neonatal outcome in singleton vs. twin pregnancies complicated by gestational diabetes mellitus

Objective: We aimed to compare placental histopathological lesions and neonatal outcome in singleton vs. twin pregnancies complicated by gestational diabetes mellitus (GDM).

Methods: Maternal characteristics, neonatal outcomes, and placental histopathology reports of pregnancies complicated by GDM, between 1/2008-10/2016, were reviewed. Results were compared between singletons (singleton group) and dichorionic-diamniotic twins (twin group). Placental lesions were classified as placental weight abnormalities, maternal and fetal vascular malperfusion lesions (MVM, FVM), inflammatory lesions, and lesions associated with chronic villitis. LGA was defined as birth-weight ≥90th percentile. Composite adverse neonatal outcome was defined as one or more early neonatal complications.

Results: Compared with the twin group (n = 57), the singleton group (n = 228) was characterized by higher gestational-age (38.6 ± 0.9 vs. 35.1 ± 1.8 weeks, p < 0.001) and a higher rate of insulin treatment (32.9% vs. 17.5%, p = 0.023). Placentas from the singleton group were characterized by higher rates of MVM lesions (54.4% vs. 30.7%, p < 0.001), villitis of unknown etiology (VUE, 5.7% vs. 0.9%, p = 0.040), villous immaturity (10.1% vs. 0.9%, p = 0.001), and placental weight <10th percentile (16.7% vs. 8.8%, respectively, p = 0.049). Using multivariable regression analysis, MVM (aOR = 2.2, 95% CI = 1.6-4.1), VUE (aOR = 1.2, 95% CI = 1.1-2.1), villous immaturity (aOR = 2.3, 95% CI 1.8-7.6), and placental weight <10th percentile (aOR = 1.1, 95% CI = 1.02-1.6), were the only lesions associated with singleton pregnancies. Composite adverse neonatal outcome was more common in the twin group (54.3% vs. 14.0%, p < 0.001) and it was associated only with lower GA (aOR = 3.7, 95% CI 2.1-7.3).

Conclusion: Higher rate of placental weight <10th percentile, MVM lesions, villous immaturity, and VUE characterize GDM singleton pregnancy as compared to twins GDM gestation, suggesting different placental alterations in the diabetic environment.