Aims: Previous studies have shown that higher hemoglobin A1c (HbA1c) levels within the normal range during pregnancy can increase the risk of adverse birth outcomes. However, the effects of the longitudinal HbA1c trajectory during pregnancy on adverse birth outcomes among non-gestational diabetic women are poorly characterized. We aimed to identify HbA1c trajectory during pregnancy among non-gestational diabetic women and to estimate their associations with adverse birth outcomes.
Methods: Data was extracted from the Information System of Guangdong Women and Children Hospital, China, from January 2017 to July 2022. This study involved 13,979 women who did not have gestational diabetes mellitus and underwent repeated HbA1c measurements during pregnancy. Latent mixture modeling was used to identify HbA1c trajectory groups. Logistic regression was applied to explore the associations between HbA1c trajectory groups and adverse birth outcomes, including preterm delivery, low birth weight, macrosomia, small for gestational age, and large for gestational age (LGA).
Results: Three HbA1c trajectory groups were identified: low-stable (range 4.0% [20 mmol/mol]-4.4% [25 mmol/mol]), moderate-stable (range 4.6% [27 mmol/mol]-5.1% [32 mmol/mol]), and elevated-increasing (range 5.0% [31 mmol/mol]-5.6% [38 mmol/mol]). Compared with the low-stable HbA1c group, the elevated-increasing group had a higher risk of preterm delivery and LGA. The adjusted OR (95% CIs) were 1.67 (1.13, 2.49) and 1.47 (1.01, 2.12) for preterm delivery and LGA, respectively.
Conclusions: Among non-gestational diabetic women, the elevated-increasing HbA1c trajectory group was associated with a higher risk of preterm delivery and LGA. This finding emphasizes the importance of maintaining optimal HbA1c levels throughout pregnancy.
Keywords: Adverse birth outcomes; HbA1c; Pregnancy; Trajectory.
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