Excessive gestational weight gain predicts large for gestational age neonates independent of maternal body mass index

Abstract

Objective: To determine the effects of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) on large-for-gestational-age (LGA) birth weight (≥90th % ile). Methods: We examined 4321 mother-infant pairs from the Ottawa and Kingston (OaK) birth cohort. Multivariate logistic regression (controlling for gestational and maternal age, pre-pregnancy weight, parity, smoking) were performed and odds ratios (ORs) calculated. Results: Prior to pregnancy, a total of 23.7% of women were overweight and 16.2% obese. Only 29.3% of women met GWG targets recommended by the Institute of Medicine (IOM), whereas 57.7% exceeded the guidelines. Adjusting for smoking, parity, age, maternal height, and achieving the IOM’s recommended GWG, overweight (OR 1.99; 95%CI 1.17–3.37) or obese (OR 2.64; 95% CI 1.59–4.39) pre-pregnancy was associated with a higher rate of LGA compared to women with normal BMI. In the same model, exceeding GWG guidelines was associated with higher rates of LGA (OR 2.86; 95% CI 2.09–3.92), as was parity (OR 1.49; 95% CI 1.22–1.82). Smoking (OR 0.53; 95%CI 0.35–0.79) was associated with decreased rates of LGA. The adjusted association with LGA was also estimated for women who exceeded the GWG guidelines and were overweight (OR 3.59; 95% CI 2.60–4.95) or obese (OR 6.71; 95% CI 4.83–9.31). Conclusion: Pregravid overweight or obesity and gaining in excess of the IOM 2009 GWG guidelines strongly increase a woman’s chance of having a larger baby. Lifestyle interventions that aim to optimize GWG by incorporating healthy eating and exercise strategies during pregnancy should be investigated to determine their effects on LGA neonates and down-stream child obesity.

Keywords::

• Gestational weight gain
• maternal obesity
• macrosomia
• pediatric obesity

Declaration of interest: Funding support was received from the Ministry of Research and Innovation—Early Researcher Award (KA) to help support the doctoral training of ZMF who is also supported by an Ontario Graduate Scholarship. Dr. Mark Walker is a CIHR New Investigator. Dr. Shi Wu Wen is a recipient of Ontario Women’s Health Council-CIHR Mid-Career Salary Award. An abstract of this paper was presented by ZMF at the 2nd National Obesity Summit in Montreal, Quebec on April 28, 2011.