Prepregnancy Prediabetes and Large‐for‐Gestational‐Age Birth Independent of Gestational Diabetes Among Asian Women

Aim Prediabetes may increase the likelihood of adverse perinatal outcomes, but evidence regarding prepregnancy prediabetes remains limited. This study examined its associations with gestational diabetes mellitus (GDM) and the delivery of a large‐for‐gestational‐age (LGA) infant. Methods This multicenter retrospective study included women who delivered at 12 obstetric facilities in Japan between January 1, 2014, and December 31, 2024, and had undergone hemoglobin A1c (HbA1c) measurement within 1 year before conception. The primary maternal and fetal outcomes were GDM and LGA birth, respectively. Multivariable logistic regression analyses were performed to evaluate each outcome, with adjustment for maternal age, assisted reproductive technology, prepregnancy body mass index, and primiparity. Results A total of 282 pregnancies were included, of which 19 (6.7%) were complicated by prepregnancy prediabetes. Prepregnancy prediabetes showed a more than twofold increase in the estimated odds of GDM (adjusted odds ratio [aOR], 2.15; 95% confidence interval [CI], 0.53–8.66), although the association was not statistically significant. In contrast, it was significantly associated with the delivery of an LGA infant (aOR, 3.48; 95% CI, 1.14–10.66). After women who developed GDM were excluded, 262 women remained, including 16 (6.1%) with prepregnancy prediabetes. In this subgroup, prepregnancy prediabetes remained significantly associated with the delivery of an LGA infant (aOR, 3.49; 95% CI, 1.09–11.57). Conclusion Prepregnancy prediabetes was independently associated with higher odds of delivering an LGA infant among Asian women, including those without a diagnosis of GDM. These findings suggest that preconception dysglycemia may help identify women at increased risk of excessive fetal growth beyond GDM diagnosis and warrant further evaluation in larger studies.