Pre-Gestational Diabetes Mellitus and Adverse Pregnancy Outcomes in 6.4 Million Women in Rural China During 2010-2016: A Population-Based, Cohort Study

Background: Pre-gestational diabetes mellitus (pGDM) and elevated fasting blood glucose level are associated with increased risk of maternal, perinatal and neonatal morbidity and mortality. Only 30.1% of those with diabetes had been previously diagnosed in China. It was reported that nearly 50.0% of Chinese population is the rural population in the population census data in 2014. It has been verified the effects of glucose level during pregnancy on adverse pregnancy outcomes. However, data of the relationship between glucose level before pregnancy and its pregnancy outcomes is scarce. We investigated the epidemiology of reproductive-aged women in China, aiming to provide the data for the prevalence of pGDM and its association with pregnancy outcomes. Methods: Data are from a nationwide sample of women of reproductive age who participated in National Free Preconception Health Examination service in 31 provinces of rural China during 2010-16. Study population characteristics were presented as mean (SD) for continuous variables and number (percentages) for categorical variable, and analysis of variance and chi square test were used to test association between each level of blood glucose concentration, risk factors and adverse outcome. Findings: Of 7,094,807 registered women (age 20-49 years), 6,447,339 were included in analyses. The incidence of pGDM and IFG was 76,297 (1.18%) and 847,737 (13.15%), respectively. Only 917 (1.20%) women were aware that they had pGDM in rural China. Among women without previously diagnosed DM, there is a positive linear association between FPG levels and incidence of combined (counted when occurrence of any of the adverse outcome) and multiple adverse pregnancy outcome(counted when having ≥2 adverse outcomes at the same time) when FPG level was divided into 7 groups ( 10mmol/L). Interpretation: The awareness rate of pGDM prevalence in rural China is extremely low. The management of pGDM is unsatisfactory in women diagnosed with pGDM. PGDM is associated with an increased risk of adverse maternal, perinatal and neonatal outcomes across all levels of FPG. Further analysis is need to support decision on the cut-off point for increased risk of adverse outcome and target blood glucose level before pregnancy to achieve satisfactory outcome. Policy decision on adoption of an extensive screening of pGDM in prepregancy examination and strategies for pGDM and adverse pregnancy outcome control from a broader perspective require more evidence on cost-effectiveness of such approaches. Funding: The National Key Research and Development Program of Reproductive Health & Major Birth Defects Control and Prevention (Grant no. 2016YFC1000402); World Diabetes Foundation (Grant no. WDF14-908). National Natural Science Foundation (Grant no. 81402757) Declaration of Interest: We declare that we have no conflicts of interest. Ethical Approval: This study was approved by the Institutional Research Review Boards at NHFPC and Peking University First Hospital, and all participants provided written informed consent.