Body Mass Index and Gestational Weight Gain During Pregnancy and Foetomaternal Outcomes: A Cohort Study at a Tertiary Health Facility in Lagos, Nigeria.

INTRODUCTION: Both body mass index (BMI) and gestational weight gain (GWG) may play a significant role in predicting events that could impact maternal and foetal health. OBJECTIVES: We determined the association between BMI and GWG versus foetomaternal outcomes and their accuracy in predicting adverse pregnancy outcomes. METHODOLOGY: A cohort study of 231 pregnant women with a singleton foetus at ≤20 weeks of gestation, who received antenatal care and delivery at Lagos University Teaching Hospital, Lagos, Nigeria, over three years between August 1, 2019, and July 31, 2022 was conducted. Data was extracted from case notes. The exposures were BMI and GWG, while the outcomes were the incidence of foetomaternal complications. Associations between categorical variables were determined using the chi-square test, and the receiver operating characteristic curve was used to determine accuracy. RESULTS: The mean age of participants was 32.7 ± 5.4 years. BMI was found to be associated with an increased incidence of maternal mortality (p = 0.006), foetal macrosomia (defined as birth weight >4 kg, p = 0.001), and stillbirths (p = 0.008). Conversely, GWG showed no significant association with any of the outcome measures (p > 0.05). Both BMI, with an area under the curve (AUC) of 0.547 (95% CI: 0.472-0.723), and GWG, with an AUC of 0.561 (95% CI: 0.487-0.635), were not meaningful predictors of adverse pregnancy outcomes. CONCLUSION: BMI and GWG are poor predictors of adverse pregnancy outcomes. However, underweight and obese pregnant women should be considered high-risk because of a higher incidence of stillbirth, foetal macrosomia, and maternal death.