A recent study showed that Obese mothers who gain excessive weight during pregnancy are nearly 7 times more likely to give birth to a large infant which themselves will be at risk of obesity.
Further, excessive gestational weight gain (GWG) increases the risk of having a large infant, even in mothers who start pregnancy with a normal body mass index (BMI). The researchers analyzed data from 4321 mother-infant pairs to investigate the effect of maternal weight and weight gain during pregnancy on the likelihood of giving birth to a child weighing more than 4000 g (8.8 pounds) which is deemed to be a cut off point for high birth weight. Mothers who reported a prepregnancy BMI indicating overweight — 25 to 29.9 kg/m2 — were nearly twice as likely to give birth to an large for gestational age (LGA) as women of healthy weight. For obese women, with a BMI of 30 kg/m2 or more, the chance of having a LGa was over 2.5 times. If a mother’s GWG exceeded the US Institute of Medicine (IOM) guidelines, the risk of having an LGA infant increased for women of any weight at pregnancy and the problem was compounded if a woman was already overweight or obese. The UK does not have specific guidelines on weight gain in pregnancy.The range of acceptable weight gain during pregnancy recommended by the IOM changes according to a mother’s weight at the time of pregnancy. Women considered underweight, with a BMI less than 18.5 kg/m2, should gain 12.5 to 18 kg (28 to 40 pounds). Healthy-weight women — BMI of 18.5 to 24.9 kg/m2 — should gain 11.5 to 16 kg (25 to 35 pounds). Overweight women are advised to gain 7 to 11.5 kg (15 to 25 pounds), and obese women, 5 to 9 kg (11 to 20 pounds). In the study, only 29.3% of the women stayed within IOM GWG guidelines.Before pregnancy, 23.7% of women in the study were overweight, and another 16.2% were obese.
J Matern Fetal Neonatal Med. 2012;25:538-542. Abstract