(1064) Clinical and Treatment-Related Predictors of SGA in GDMA2 patients treated with Metformin

Concerns have emerged regarding a possible association between metformin treatment for gestational diabetes mellitus (GDM) and increased risk of small for gestational age (SGA) neonates. While this has been reported in type 2 diabetes, data in GDMA2 pregnancies remain limited. We aimed to identify clinical and treatment-related risk factors for SGA among metformin-treated women with GDMA2.

 

Study Design:

We conducted a retrospective cohort study of singleton GDMA2 pregnancies treated with metformin at a tertiary center. Neonates were categorized as SGA (< 10th percentile) or appropriate for gestational age (AGA). Maternal, obstetric, and neonatal characteristics were compared. Multivariable logistic regression was performed to identify independent predictors of SGA. Exclusion criteria included pregestational diabetes and fetal anomalies.

 

Results:

Of 397 metformin-treated women, 46 (11.6%) delivered SGA neonates. In univariate analysis, SGA was associated with female fetal sex (62.9% vs. 28.3%, p< 0.01), primiparity (43.5% vs. 22.8%, p=0.002), lower prior birth weight (2637g vs. 3023g, p=0.019), and earlier metformin initiation (≤28 weeks: 54.3% vs. 37.1%, p=0.024). In multivariable analysis, female fetal sex (aOR 0.039; 95% CI 0.004–0.373; p=0.005) and lower prior birth weight (aOR 0.999; 95% CI 0.998–1.000; p=0.016) were independently associated with SGA. Initiation of metformin ≤28 weeks was borderline significant (aOR 4.098; 95% CI 0.93–18.01; p=0.062). Metformin dose, duration, insulin co-treatment, weight gain, and glycemic control were not associated with SGA.

Conclusion:

Among metformin-treated GDMA2 pregnancies, fetal female sex and lower prior birth weight were significantly associated with SGA. Early metformin initiation showed a borderline association. These findings highlight the need for a risk-based and individualized approach to metformin use in GDMA2.