Excessive weight gain during pregnancy a predictor for above-average birth weight

"Obesity can become part of an intergenerational cycle," said Dr. Kristi Adamo, co-author of this report and co-founder of the Healthy Active Living and Obesity (HALO) Research Group at the CHEO Research Institute. "Birth weight averages can be an indicator of the weight a child will carry through preschool and even into adulthood. It's critical for a mother to understand that her healthy eating and lifestyle decisions during pregnancy will impact much more than a nine-month gestation period."

To investigate this issue in more detail, Dr. Adamo and her colleagues examined data from more than 4,000 mother and baby pairs cared for at The Ottawa Hospital and the Kingston General Hospital between 2002 and 2009. They found that excessive gestational weight gain (GWG) can be just as problematic as pre-pregnancy overweight and obesity. In fact, the study indicated that independent of pre-pregnancy body mass index (BMI), mothers who exceeded GWG recommendations specific to their pre-pregnancy BMI significantly increased the likelihood that their child would be born larger than average for gestational age (i.e. above the 90th percentile of infant weight for gestational age.)

"It doesn't matter if you're categorized as normal weight, overweight or obese during pre-pregnancy -- exceeding the 2009 Institute of Medicine GWG targets seems to have a growth promoting effect on the fetus," explained the co-author Zach Ferraro, a PhD student in Dr. Adamo's lab and in the Human Kinetics doctoral program at the University of Ottawa. He is co-supervised by Dr. Denis Prud'homme, co-author of this report and dean of the Faculty of Health Sciences. "Unfortunately, delivering a large baby increases the risk for many delivery-related complications in both mom and baby. But the takeaway here is that GWG is a modifiable risk factor that can and must be addressed during prenatal visits for all women!"

The data for this study was obtained from the Ottawa and Kingston (OaK) Birth Cohort, developed by Drs. Mark Walker, Shi Wu Wen and Marc Rodger of the Ottawa Hospital Research Institute and the University of Ottawa. The study was funded by the Ontario Ministry of Research and Innovation, the Canadian Institutes of Health Research, the Ontario Women's Health Council, and the Heart and Stroke Foundation of Canada.