With a growing trend of obesity in children and teenagers, parents are increasingly concerned with the health of their children. Research from the University of North Carolina suggests that whether a mother is obese during pregnancy, and how much weight she gains during pregnancy, can affect whether her child will become obese later in life.

The study, published in the International Journal of Obesity, followed the weight gain of 24 000 pairs of mothers and daughters. The results found that when mothers were overweight before pregnancy, their daughters were twice as likely to become obese by the age of 18 as daughters born to mothers with a normal pre-pregnancy weight.

The study also found that gaining too much or too little weight during pregnancy could also increase the risk of the child becoming obese. The lowest risk of the daughter becoming obese by age 18 was linked with moderate weight gain in the mother — about 15 to 19 pounds.

However, if the mother gained more than 40 pounds during pregnancy, her daughter was twice as likely to become obese by age 18, and if the mother gained less than 10 pounds, the daughter was about 1.5 times as likely to be obese by 18.

The study from the University of North Carolina is supported by other research as well. One of the studies was conducted by the Agricultural Research Service, and showed that rat mothers who were obese during pregnancy gave birth to rat pups that tended to become overweight when allowed to eat an unlimited amount of food, in comparison to rat pups that were born to lean rat mothers. Both groups of rat pups had normal weight at birth and weaning, but after weaning, the pups who were born to obese mothers showed a much higher propensity to eat high-fat food and gained significantly more fat. The research indicates that the mother’s obesity could affect the unborn baby’s metabolism and weight-regulating mechanisms, leading the babies to become overweight later in life.

Taking into account the research about maternal obesity, the Institute of Medicine revised its maternal weight gain recommendations in 2009. The IOM recognized that with women with different body-mass indexes (BMI), a range of different weight gains should be recommended. With these new guidelines, health-care providers should consider the mother’s height, weight, and weight gain during pregnancy, with obese mothers gaining less weight during their pregnancy, and underweight mothers gaining more. The report on maternal weight by the IOM is provided here: Weight Gain During Pregnancy.

The IOM stressed the importance of would-be mothers conceiving at a normal Body-Mass-Index (ie. healthy body weight). During pregnancy, women should also stick to a healthy diet and get regular physical activity, in consultation with their health-care provider.