Maternal super obesity is increasing and is associated with an increased risk of pregnancy complications-a call for concern.

Objective: This study aimed to assess the relationship of increased body mass index (BMI) with pregnancy complications.

Study design: We obtained data for a retrospective cohort of singleton live births using an electronic birth certificate database from 2010 to 2022. Institutional review board exemption was obtained. BMI was assessed as a continuous variable and a categorical variable with groups of BMI 18.5-29.9 kg/m², 40-49.9 kg/m², and ≥50 kg/m² compared to patients with BMI 30-39.9 kg/m². Primary outcomes were pregnancy and maternal outcomes. Secondary outcomes were neonatal outcomes. ANOVA and χ² were used to compare continuous and categorical variables respectively, and logistic regression was used to obtain adjusted odds ratios for primary and secondary outcomes.

Results: There were 223,837 patients with singleton live births with mean BMI 27.86 kg/m2. 54,385 (24.3%) had BMI 30-39.9 kg/m2, 13,299 (5.9%) had BMI 40-49.9 kg/m2, and 1,958 (0.87%) had BMI ≥50 kg/m2. Patients with BMI > 50 kg/m2 have a higher likelihood of APGAR scores <7 (aOR 1.38, 95% CI 1.05-1.83), and NICU admission or transfer out of facility (aOR 1.17, 95% CI 1.02-1.34). In the nulliparous subgroup analysis, For patients with BMI >50 kg/m2, there was a higher odds of preterm birth <37 weeks (aOR 1.57, 95% CI 1.23-2.00) and preterm birth <34 weeks (aOR 1.51 95% CI 1.00-2.30. There is also an increased odds of cesarean section in both of these BMI groups (aOR 1.68 95% CI 1.57-1.79 and aOR 2.30 95% CI 1.94-2.72).

Conclusion: BMI ≥ 50 kg/m² was significantly associated with increased pregnancy complications.