A mother’s weight gain during pregnancy was incrementally associated with elevated BMI and odds of overweight and obesity in offspring through 12 years of age, study findings indicate.
In a cohort of women with two or more pregnancies, each kg of weight gained during pregnancy was significantly associated with an increase in the child’s BMI (95% CI 0.0134-0.0306, P<0.0001) at around 12 years of age, David Ludwig, MD, PhD, of Boston Children’s Hospital, and colleagues reported in PLoS Medicine.
Similarly, for every kg of weight gained in pregnancy the child’s risk for being overweight or obese increased significantly (OR 1.007; 95% CI: 1.003-1.012; P=0.0008).
The study involved 42,133 Arkansas women with more than one singleton pregnancy and 91,045 of their children. The researchers analyzed the relationship between maternal weight gain during pregnancy and the child’s weight at a mean age of 11.9 years.
They used data from the Vital Statistics Natality records on pregnancy weight gain, baby’s birth weight, gestational diabetes status, the week of gestation at delivery, maternal age, marital status, maternal smoking, child’s sex, parity and year of birth.
Maternal weight-gain was determined by subtracting reported pre-pregnancy weight from weight at delivery. The researchers collected children’s weight and height from school records to calculate BMI.
Mothers gained a mean 3.9 kg from their pre-pregnancy weight, the researchers found. Mean age was 24.5 years and 17.9% reported smoking.
Children had a mean birth weight of 3,416.5 g, a mean gestation of 39.3 weeks and 39.4% were overweight or obese at the time of their last BMI measurement.
After adjustment, each kg of maternal weight gained during pregnancy was associated with a childhood BMI increase of 0.0143 kg/m2 (95% CI 0.0057-0.0229, P=0.0007).
“[O]ur study suggests that overnutrition in pregnancy may program the fetus for an increased lifetime risk for obesity, though the magnitude of this effect may be small,” the researchers concluded.”However, because inadequate weight gain during pregnancy can also adversely affect the developing fetus, it will be essential for women to receive clear information about what constitutes optimal weight gain during pregnancy.
Study limitations include the potential for errors in reporting pregnancy weight gain and a lack of data for pre-pregnancy BMI.