Chorionicity and gestational diabetes mellitus in twin pregnancies in relation to placental weight

Background: Gestational diabetes mellitus (GDM) is glucose intolerance first detected during pregnancy. Twin pregnancies have a higher risk of GDM, likely due to increased placental mass and elevated placental lactogen levels. Objective: The aims of this study were 1) to assess the impact of chorionicity on the development of GDM in twin pregnancies and 2) to assess a possible association between placenta weight and the development of GDM. Methods: We conducted a prospective cohort study of all women with twin pregnancies (N = 819) at the department of Obstetrics and Gynecology, Lillebaelt University Hospital, Kolding, Denmark, between January 1, 2007 and April 30, 2019. Information on chronicity was determined at the first visit with ultrasonic imaging, during weeks' gestation 11-13. Oral glucose-tolerance test was performed to diagnose gestational diabetes mellitus. Results: Among 819 twins, 17.8% were monochorionic twins and 82.2% were dichorionic twins. There were no statistically significant difference of GDM prevalence between monochorionic twins group 7.4 % and dichorionic twins group 9.8 % (P = 0.42). Placenta's weight in dichorionic twins was larger compared with monochorionic twins. No association was found between the weight of placenta and the prevalence of GDM (P = 0.21), even after adjustment for body mass index, gestational age, and fertility treatment (P = 0.87). Conclusions: Our study could not find an association between chorionicity, placental weight, and GDM. It is, therefore, possible that twin pregnancies, regardless of chorionicity and placental weight, have the same risk for GDM.