According to a study published in Lancet on August 5, infants born to women who gain too much weight during pregnancy are more likely to become overweight children and adults later in life.

More than 500,000 health records were reviewed for the study. Pregnant women who gained more than 53 pounds during pregnancy with a single fetus were two times more likely to give birth to an infant weighing nine pounds or more when compared to women gaining only 18 to 22 pounds.

There has been a consistent increase in babies being born weighing more than the average infant. This result is thought to be attributed to an increase in obesity rates in the adult population. On average, obese and overweight women who conceive tend to gain more weight while pregnant than a pregnant woman of normal weight at conception.

Guidelines for weight gain during pregnancy differ based upon the BMI of a woman at conception. Women with a normal BMI are supposed to gain between 25 and 35 pounds during pregnancy. Underweight women can gain up to 40 pounds. Women who are overweight or obese, falling within the BMI range of 30 or higher, should gain no more than 20 pounds. These numbers are relevant for a singlet pregnancy only. Being pregnant with multiples will result in more weight gain.

Genetic factors are not ruled out for people who come from a long line of overweight people, but researchers believe more weight could be placed on pregnancy weight gain over genetic factors leading to weight gain later in life.

Source: David Lancet MD, Janet Currie PhD. The Lancet. 5 August 2010