Putting on too few or too many pounds during a pregnancy "may permanently affect mechanisms that manage energy balance and metabolism in the offspring, such as appetite control and energy expenditure," study author Sneha Sridhar, of Kaiser Permanente's Division of Research, theorized in a Kaiser news release.
"This could potentially have long-term effects on the child's subsequent growth and weight," she said.
In the study, Sridhar's team looked at the medical records of children aged 2 to 5 born to more than 4,100 women in California.
They found that 20.4 percent of those children whose mothers gained more than the recommended amount of weight during pregnancy were overweight or obese, compared to 14.5 percent of those whose mothers gained weight within recommended guidelines.
Similar numbers arose when the researchers compared overweight rates for children whose mothers gained less than the recommended amount of weight during pregnancy.
Among women with a body-mass index (a measurement of body fat based on height and weight) in the normal range before pregnancy, those who gained less than the recommended amount of weight during pregnancy were 63 percent more likely to have an overweight or obese child, the researchers said. The risk was 80 percent higher among those who gained more than recommended amount of weight during their pregnancy.
The study could only point to an association between pregnancy weight gain and a child's risk for obesity; it could not prove cause and effect. But according to senior study author Monique Hedderson, also from Kaiser Permanente, the fact that the trend was found among non-obese, normal weight women "suggests that perhaps weight gain in pregnancy may have an impact on the child that is independent of genetic factors."
Current Institute of Medicine guidelines for weight gain during pregnancy are: for obese women (a BMI of 30 or above), 11 to 20 pounds; for overweight women (BMI of 25 to 29), 15 to 25 pounds; for normal weight women (BMI Of 18.5 to 25), 25 to 35 pounds; and for underweight women (BMI under 18.5), 28 to 40 pounds.
The study was published April 14 in the American Journal of Obstetrics and Gynecology.
The March of Dimes has more about weight gain during pregnancy.