Pregnancy and Weight Gain
The average weight of American men and women has been increasing for a long time, but the increase has been particularly pronounced since 1980. Over the same period, childhood obesity has increased greatly and today nearly one out of every 5 American children is classified as obese.
Over the past 20 years, the percentage of American men and women of childbearing age who are overweight or obese has nearly doubled. For women, more than half are overweight, and about one-third are obese. Statistics for men are similar. Thus, more American men and women are entering pregnancy overweight or obese than ever before. In addition, the proportion of women who gain too much weight during pregnancy has increased since 1990. Today, according to the Institute of Medicine1, 1 in 5 American women gain more than 40 pounds during pregnancy and nearly all women gain more than is recommended.
This is important for several reasons. First, during pregnancy, overweight women face serious health risks including high blood pressure and diabetes conditions that are harmful to both mother and baby. Overweight moms also face a higher risk of premature delivery by surgery (Caesarean section). The more overweight a woman is when she becomes pregnant, the higher these health risks to both mother and baby. The infants born to overweight or obese mothers (and fathers) face greater health risks. These babies are fatter at birth and they face a higher risk of obesity by the age of 4. All of these risks increase higher still if the mother gains more than the recommended amount of weight during pregnancy.
Second, the more weight a pregnant woman gains during pregnancy, the more weight she will retain postpartum – that is after she gives birth. Women who gain too much during pregnancy are more likely to retain an extra 10 to 20 pounds beyond 6 months postpartum. This applies to women of all races and ethnicities and all levels of pre-pregnancy body mass index (BMI). In short — women who gain more than the recommended amount are less likely to return to their pre-pregnancy body weight. This matters because the health risks for both mother and baby will be much higher in a subsequent pregnancy, because the mother is entering that pregnancy at a higher BMI.
To give you an idea of how parental overweight and obesity increases the risk of childhood obesity, in one study2 of more than 4400 families who gave birth to more than 7000 children, researchers found a much higher risk of childhood obesity when the parents (either the mother or the father) was overweight or obese. The higher the parental BMI, the greater the risk of childhood obesity. Compared to parents of normal weight (defined as a pre-pregnancy BMI falling between 18.5 to 25.0):
- If both parents were overweight, the risk of childhood obesity in the offspring doubled
- If both parents were obese, the risk of childhood obesity increased about 10 times
- If both parents were severely obese, the risk of childhood obesity increased about 20 times
To prevent childhood obesity and other health risks for parents and children it would be ideal if all people who might become parents someday would maintain a healthy BMI of no less than 18.5 and no more than 24.9. Since most pregnancies are unplanned, this is good advice for everyone.
1 Institute of Medicine
2 Whitaker KL et al. Comparing maternal and paternal intergenerational transmission of obesity risk in a large population-based sample. AJCN 2010; 91:1560-1567