Adults whose moms were obese may die sooner, study says

Middle-aged adults whose mothers were obese or overweight in pregnancy have increased risks for developing serious cardiovascular problems and dying young, a new study shows.

The study, based on the health records of more than 37,000 people born in Scotland between 1950 and 1976, does not explain why a mother's weight would affect the health of an adult child decades later. Genes and upbringing may play roles. But the results also add to growing evidence that adverse conditions in the womb might have profound effects on offspring long after birth, says the study, published Tuesday in the British medical journal BMJ.

"It's very difficult to tease out," causes and effects when it comes to intergenerational health problems, says lead researcher Rebecca Reynolds, professor of metabolic medicine at the University of Edinburgh. But she says the results lend credence to a theory that "over-nourished" fetuses may develop differences in their brains, blood vessels, hearts or metabolisms that make it more likely for them to become obese, unhealthy or both.

The study focused on adults ages 34 to 61 and linked their records with those from their mothers' first prenatal visits. After accounting for socioeconomic status, mothers' ages and other differences that might matter, researchers found that those born to obese women were 35% more likely to die, for any reason, and 29% more likely to be hospitalized for heart attacks, strokes or other cardiovascular problems when compared to adults who had normal-weight mothers. Cardiovascular diseases and cancer were the most common causes of death.

More modest increases in illness and death were seen among the grown children of women who were overweight but not obese.

The researchers defined overweight and obese by body mass index (BMI), a measure that takes weight and height into account. Mothers were considered obese if their BMIs were 30 or higher and overweight if their BMIs were between 25 and 29. It's not known whether the adults who got sick or died tended to share their mothers' weight problems. The study did show that the results held up whether or not babies were born heavy, Reynolds says.

The study "is certainly intriguing," though it lacks crucial information "on what happens between birth and midlife," in homes where children are raised by overweight and obese mothers, says Pam Factor-Litvak, an associate professor of epidemiology at Columbia University, New York. It also lacks information on fathers, she notes. Genes, shared diets and other factors need to be studied, she says.

But the suggestion that the womb environment sets the stage for later-life cardiovascular health and mortality is important to pursue, she says in an editorial accompanying the study.

In any case, there already are many good reasons for women to enter pregnancy at healthy weights and not to gain too much during the nine months, says Jeanne Conry, president of the American College of Obstetricians and Gynecologists. The college recommends that women talk with their doctors about weight at every routine check-up, before and between pregnancies. Women who start a pregnancy obese have an increased risk of developing diabetes and high blood pressure, having a Cesarean section and having a baby with birth defects, she says.

"You see an immediate effect on the fetus, so it's not too much of a leap to say we may see long-term impacts," says Conry, an obstetrician/gynecologist at Kaiser Permanente in Sacramento.

The issue is pressing, she says, because obesity among pregnant women has risen 70% in just the past decade in the United States.

Reynolds notes that just 4% of the mothers in her study were obese — but that 35% of reproductive-age women in the United States today are obese and that rates are similar in Europe.