Association of Normal-Range Hemoglobin A1c Value During Midpregnancy with Adverse Birth Outcomes

BACKGROUND: The midpregnancy normal-range HbA1c value and adverse birth outcomes were controversial. To address this lack of data, we examined the associations between midpregnancy normal-range HbA1c value and adverse birth outcomes. OBJECTIVE: To evaluate whether an association exists between the midpregnancy normal-range HbA1c value and adverse birth outcomes. MATERIALS AND METHODS: A total of 8389 women in their midpregnancy with normal gestational HbA1c value from the Affiliated Hospital of Jining Medical University in China participated in this study from January to December 2019. Subjects were stratified on the basis of their midpregnancy HbA1c value, and multivariate logistic regression was implemented to investigate the association between different HbA1c values and adverse birth outcomes. RESULTS: Incidence of preterm birth, macrosomia, and large for gestational age (LGA) for 8389 subjects were 4.8%, 6.3% and 16.5%, respectively. The multivariate logistic regression model demonstrated that the risk of preterm birth (adjusted odds ratio [OR]: 1.71 and 95% confidence interval [CI]: 1.25–2.34), macrosomia (OR: 1.68 and 95% CI: 1.26–2.22), and LGA (OR: 1.53 and 95% CI: 1.28–1.83) increase for every increase of 1% maternal HbA1c. Women with a prepregnancy body mass index (BMI) of < 25 kg/m(2) have a stronger correlation with HbA1c values and adverse birth outcomes than women with a prepregnancy BMI of ≥25 kg/m(2). CONCLUSION: Our results indicated that the midpregnancy normal-range HbA1c level within the normal range is associated with adverse birth outcomes. Monitoring and controlling HbA1c may reduce the risk of adverse birth outcomes.