Association between maternal plasma glucose levels during pregnancy and risk of preterm birth: a retrospective study

Abstract Background Preterm birth is a leading cause of health problems and death in infants. This study aims to investigate the association between maternal plasma glucose levels during pregnancy and risk of preterm birth. Methods This population-based retrospective study of 6,842 pregnant women used data from a tertiary hospital in China from January 2016 to December 2022. Plasma glucose levels were measured at fasting, 1 h, and 2 h after a 75-g OGTT between 24 and 28 weeks of gestation. The primary outcome of interest was preterm birth. Analysis was performed using restricted cubic splines and logistic regression models. Results The proportion of gestational diabetes mellitus (GDM) and preterm birth in this study were 7.92% and 5.86%, respectively. The levels of fasting plasma glucose (aOR: 1.26; 95% CI: 1.08, 1.47; P = 0.003; P for nonlinear = 0.264), 1-hour plasma glucose (aOR: 1.10; 95% CI: 1.03, 1.17; P = 0.003; P for nonlinear = 0.535), and 2-hour plasma glucose (aOR: 1.10; 95% CI: 1.02, 1.19; P = 0.012; P for nonlinear = 0.368) showed statistically significant linear associations with an increased risk of preterm birth. Conclusion Elevated plasma glucose levels during pregnancy statistically significantly increase the risk of preterm birth. Given that hyperglycemia during pregnancy can be prevented and managed, it is crucial to enhance health education and glucose monitoring for pregnant women. Timely interventions should be implemented to control plasma glucose levels, thereby reducing the incidence of preterm birth.