The impact of abnormal maternal body mass index during pregnancy on perinatal outcomes: a registry-based study from Qatar.

Objectives: Abnormal body mass index (BMI) during pregnancy, a growing public health concern, increases maternal and neonatal complications. This study aimed to investigate the impact of abnormal BMI on perinatal outcomes compared to normal BMI.

Methods: A total of 14,624 women having singleton births were categorized as underweight (BMI<18.5 kg/m), overweight (25.0-29.9 kg/m), obesity class I (30.0-34.9 kg/m), obesity class II (35.0-39.9 kg/m), and obesity class III (≥40.0 kg/m) and compared to those with normal BMI (18.5-24.9 kg/m). Outcomes included gestational diabetes (GDM), gestational hypertension (GHT), postpartum haemorrhage (PPH), cesarean delivery (CD), preterm birth (PTB), low birth weight (LBW), congenital anomalies and neonatal intensive care unit admission.

Results: Women with increasing BMI had increasingly higher odds of developing specific adverse outcomes, the highest being in the class III obesity group (GDM-aOR 2.71, 95 % CI 2.25-3.27, p<0.001, GHT-aOR 5.32 95 % CI 3.49-8.11, p<0.001, CD-aOR 2.33 95 % CI 1.85-2.94, p<0.001, PPH-aOR 1.77 95 % CI 1.35-2.33, p<0.001). On the other hand, being underweight during pregnancy was associated with increased odds of PTB (aOR 2.09, 95 % CI 1.37-3.20, p=0.001), LBW (OR 1.88, 95 % CI 1.27-2.79, p=0.002) and congenital anomalies (aOR 2.52 95 % CI 1.12-5.64, p=0.025). Majority in the underweight category gained less than expected gestational weight gain during the pregnancy.

Conclusions: The findings of this study have important implications for the clinical management of pregnant women with abnormal BMI. Interventions to improve maternal and neonatal outcomes must focus on enhancing pre-pregnancy BMI and maintaining adequate gestational weight gain.