Impact of maternal body mass index above 30 kg/m2 on adverse pregnancy outcomes in women with and without gestational diabetes mellitus in southeastern Sweden.

Abstract

Introduction: Our objective was to evaluate the association of early-pregnancy body mass index (BMI) in women with gestational diabetes mellitus (GDM) with maternal, delivery, and child outcomes, and compare with pregnancies without diabetes in southeastern Sweden, including after a surge of non-European immigration.

Material and methods: A retrospective population-based observational study of all 401 singleton pregnancies with GDM in the Kronoberg and southern Kalmar regions, 2013-2018, and 377 pregnancies without diabetes, matched by date of delivery. Data were collected by chart review. Women with early-pregnancy BMI <30 kg/m²/≥30 kg/m² were compared. Main outcomes were gestational weight gain (GWG), continuous and dichotomized <8 kg/≥8 kg, preeclampsia, cesarean section (CS), and large-for-gestational-age (LGA). Maternal age, ethnicity, parity, smoking, physical activity, delivery type and week, birthweight, and the APGAR_5min score were also registered.

Results: Obese women with GDM had lower mean GWG (9.2 ± 6.8 vs. 11.7 ± 6.1 kg); fewer reached ≥8 kg (54% vs. 75%), more had preeclampsia (13% vs. 2.6%), and infants weighed 200 g less than those of nonobese women with GDM all p < 0.001 and those of obese women without GDM (11.2 ± 5.8 kg, p < 0.001; 68%, p = 0.05, 3.1%, p = 0.03). APGAR_5min scores were high in all groups, 9.4-9.8. All women with GDM had a higher prevalence of LGA infants than controls without diabetes; obese 24% versus 12% (p = 0.03) and nonobese 11% versus 6% (p = 0.05). Obese women with GDM delivered more LGA infants than nonobese women with GDM, p = 0.001. The combination of GDM and obesity increased risk of LGA, OR 5.3 (2.76-10.1); preeclampsia OR 4.3 (1.83-10.23); and CS OR 1.9 (1.26-2.97) and decreased odds of GWG ≥8 kg, OR 0.25 (0.16-0.38), compared to the reference group of nonobese women without GDM. All results remained unchanged in a sensitivity analysis using the BMI obesity limit ≥27.5 kg/m² for Asians, who were overrepresented in the group of women with GDM.

Conclusions: Women with GDM and obesity, especially in combination, had a greater risk for preeclampsia, CS, and delivering LGA infants; their lower GWG and high APGAR_5min scores in all groups, compared to earlier studies, suggested successful care interventions. Efforts to lower the levels of early-pregnancy obesity and strict glucose control in women with GDM are recommended to reduce adverse outcomes.