Maternal pre-pregnancy body mass index and the risk for gestational diabetes mellitus in women with twin pregnancy in South Korea

Objective: To investigate the association between maternal pre-pregnancy body mass index (BMI) and the risk for gestational diabetes mellitus (GDM) in women with twin pregnancy in South Korea. Materials and methods: We performed a single-center, retrospective cohort study involving 1028 women with twin pregnancy from January 2006 to December 2018 in South Korea. Pregnancies with monoamnionic twins, twin-twin transfusion syndrome, fetal death in utero before 24 weeks, pre-gestational diabetes mellitus, and unknown BMI or GDM status were excluded. Subjects were grouped into four groups based on pre-pregnancy BMI: underweight (<18.5 kg/m2), normal (18.5-22.9 kg/m2), overweight (23.0-24.9 kg/m2), and obese (>25.0 kg/m2). Results: Among 1028 women who were included in the analysis, 169 (16.4%), 655 (63.7%), 111 (10.8%), and 93 (9.0%) women were underweight, normal, overweight, and obese, respectively, before pregnancy. The incidence of GDM was 8.9% in the total study population: 4.7%, 8.2%, 11.7%, and 17.2% in the underweight, normal, overweight, and obese group, respectively (p = 0.005). The incidence of GDM significantly increased according to the increase in pre-pregnancy BMI (p < 0.001). Women in the obese group were more likely to be affected by GDM compared to the normal group (adjusted odds ratio = 2.20, 95% confidence interval = 1.19-4.08) after controlling for maternal age, parity, type of conception, and chorionicity. Conclusion: In twin pregnancies in South Korea, the risk of GDM increased as maternal pre-pregnancy BMI increased and obese women before pregnancy were more likely to be affected by GDM. (c) 2021 Taiwan Association of Obstetrics & Gynecology. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).