Objective: To estimate the association between maternal overweight and obesity on complications during pregnancy and delivery in Denmark.
Methods: A population-based study on a cohort consisting of all Danish women giving birth to a singleton from 2004 through June 30, 2010 (N = 403,092) was undertaken. Women were identified from the Danish Medical Birth Registry, which contains data on 99.8% of all deliveries in Denmark. Maternal complications during pregnancy and delivery and fetal complications were classified according to the International Classification of Diseases, 10th Revision.
Results: The final study population consisted of 369,347 women, 20.9% being overweight (body mass index [BMI] 25-29.9), 7.7% obese (BMI 30-35), and 4% severely obese (BMI higher than 35). Overweight, obese, and severely obese women had more complications than did normal weight women. Adjusted odds ratios (ORs) were significantly increased as follows: for gestational diabetes mellitus, 3.5, 7.7, and 11.0 for each BMI category; for preeclampsia 1.9, 3, and 4.4. Planned and especially emergency cesarean delivery was significantly increased with increasing BMI (OR ranging from 1.2 to 2.1). The risk of giving birth to a macrosomic neonate (greater than 4,500 g) increased significantly with increasing BMI (1.6, 2.2, and 2.7), as did the risks of having a neonate with a low Apgar score (1.3, 1.4, and 1.9) and having a stillborn fetus (1.4, 1.6, and 1.9). For shoulder dystocia the risk was significantly increased in the unadjusted analysis, but the significance disappeared in the adjusted analysis. No statistically significance was seen for hemorrhage and thrombosis.
Conclusion: This study shows a significant increased risk of a wide variety of pregnancy, birth, and neonatal complications in overweight, obese, and severely obese women.
Level of evidence: II.