Comparative risk of gestational diabetes mellitus following fresh and frozen embryo transfers: a retrospective cohort study in Palestinian women undergoing in vitro fertilization

Abstract Background Gestational diabetes mellitus (GDM) is a common metabolic complication of pregnancy and is increasingly recognized among women conceiving through assisted reproductive technology (ART). However, whether the type of embryo transfer fresh or frozen affects GDM risk remains controversial, particularly in non-PCOS populations. This study aimed to compare the incidence of GDM between fresh and frozen embryo transfer (ET) and identify independent metabolic predictors of GDM among Palestinian women undergoing in vitro fertilization (IVF). Methods This retrospective cohort included 416 women who achieved singleton pregnancies following IVF between 2021 and 2025 at two fertility centers in Palestine. To minimize confounding, women with polycystic ovary syndrome (PCOS), multiple gestations, advanced maternal age (> 35 years), pre-existing diabetes, or other endocrine disorders were excluded. Clinical and metabolic parameters assessed included maternal age, pre-pregnancy body mass index (BMI), blood pressure, infertility duration, and number of IVF cycles. GDM was diagnosed according to the American Diabetes Association/International Association of Diabetes and Pregnancy Study Groups (ADA/IADPSG) one-step 75-g oral glucose tolerance test. Multivariable logistic regression analysis was performed to determine independent predictors of GDM. Results The overall incidence of GDM was 37.7% (157/416), with a significantly higher rate among women who underwent fresh ET 42.5% (93/219) compared with frozen ET 32.5% (64/197). After adjustment for potential confounders, frozen ET remained independently associated with a 52% lower risk of GDM (aOR = 0.48, p = 0.002). In the regression model, higher pre-pregnancy BMI (aOR = 1.10; 95% CI, 1.06–1.14; p < 0.001), longer infertility duration (aOR = 1.18; 95% CI, 1.05–1.33; p = 0.006), and greater number of IVF cycles (aOR = 1.21; 95% CI, 1.03–1.42; p = 0.018) emerged as independent predictors of GDM. In the frozen ET subgroup, elevated pre-pregnancy blood pressure was also significantly correlated with increased GDM risk. Conclusion Fresh ET was associated with a higher incidence of GDM compared with frozen ET, even after adjusting for multiple confounders. While this association may be related to the supraphysiologic hormonal milieu of fresh cycles, causality cannot be inferred. The findings highlight BMI, infertility duration, number of IVF cycles, and pre-pregnancy blood pressure as key determinants of GDM risk among IVF pregnancies. These findings highlight the importance of individualized ART protocols to optimize maternal metabolic health and support early metabolic screening for women at risk. For future prospective, large-scale studies are needed to confirm these associations and refine clinical strategies to mitigate GDM risk in IVF pregnancies.