Fallout from mom’s weight may linger beyond childhood, say Israeli researchers who looked at clinical information on 1,400 young adults born between 1974 and 1976, including data on their mothers’ weight before pregnancy. By age 32, those whose mothers’ prepregnancy weight was in the upper 25 percent had higher risks for heart and metabolic disease than those with moms in the lowest 25 percent. Their waists averaged 3.3 inches larger, their BMI averaged five points higher, and they had significantly higher blood pressure and blood levels of sugar and fat.
Paradoxically, dieting at the time of conception could also be problematic. An animal study found that eating too little at the start of pregnancy altered DNA in a part of the fetal brain related to food and blood sugar, which boosted the offspring’s risk of being overweight later in life.
What to do
Already-heavy women are the most likely to gain excess pregnancy weight—Josefson’s study found a 70 percent likelihood!—but about one-third of normal-weight women also gain too much. Aside from postponing pregnancy until your weight is normal, the best thing you can do for your baby is eat right while you’re expecting. A review of 44 studies found that expectant moms who ate a balanced, healthy diet gained an average of 9 fewer pounds than those who ate as usual. In contrast, moms-to-be who exercised but ate their usual diet gained just 1.5 fewer pounds.
Even dieting is gaining acceptance, though only for obese women who have their doctor’s OK. A balanced diet that enables them to gain little or no weight during pregnancy is not only safe for the baby, it can help prevent preeclampsia, diabetes, high blood pressure and premature birth.
Obesity and your baby’s brain
Scientists have discovered that a mother’s weight can alter the delivery of nutrients to the fetal brain. One study showed that obese moms risked delivering babies with low iron reserves, perhaps because obesity promotes production of the hormone hepcidin, which may interfere with the transfer of iron to the fetus. Iron is crucial to the central nervous system; deficiency puts babies at risk for delays in motor and cognitive development.
Other research found that the children of moms who were obese before pregnancy tested two points lower in math and three points lower in reading at ages 5 and 7. The differences seem slight, but they correlate with seven fewer years in a mother’s education and significantly lower household income, both classic risk factors for low test scores.