Many mothers-to-be relish the idea of 9 months of eating for two and giving in to cravings of pickles and ice cream. But, a new study indicates that women who gain excessive weight during pregnancy are more likely to have heavier babies, and these children may grow up with long-term adverse health consequences.

The authors of the study, published in the The Lancet, analyzed the weight gain of more than 500,000 mothers in the United States who gave birth to more than 1.1 million infants over a period of 14 years. The authors reported that excessive weight gain during pregnancy increases not only the infant’s birth weight, but also the child’s risk of obesity later in life. Since the study analyzed multiple pregnancies of the same mothers, genetic factors were ruled out as confounders of the results. The authors excluded births that included gestational age less than 37 weeks or more than 41 weeks, maternal diabetes, and birth weights less than 500 g (1.1 lbs) or more than 7000 g (15.4 lbs).

Among the population analyzed, each kilogram of weight gained by a mother increased the baby’s birth weight by 7.35 g. Mothers who gained more than 24 kg (52.8 lbs) during pregnancy gave birth to infants who were approximately 150 g heavier, weighing 4 kg (8.8 lbs) or more on average, than infants of women who gained 8 to 10 kg (17.6-22 lbs). The authors also emphasized the association between birth weight and adult obesity, as well as chronic conditions like asthma, allergies, and cancer. This report underscores the need to help women of reproductive age maintain healthy body weights before and during pregnancy.

Prepregnancy weight predicts pregnancy outcomes, also, according to related research. The effect of weight gain on adverse pregnancy outcomes depends on prepregnancy body mass index (BMI). Currently, weight gain recommendations vary according to prepregnancy BMI: normal weight women (BMI 18.5-24.9), 25 to 35 lbs; underweight women (BMI less than 18.5), 28 to 40 lbs; overweight women (BMI 25-29.9), 15-25 lbs; and obese women (BMI greater than 30), 11-20 lbs. These recommendations are guidelines for ensuring a healthy birth weight, preventing pregnancy and birth complications, and preventing postpartum maternal overweight and obesity. In most cases, appropriate weight gain during pregnancy decreases the risk of adverse consequences such as gestational hypertension, augmentation of labor, preterm birth, metabolic abnormalities in the newborn, and long-term maternal weight retention. Current evidence reports that only 33% to 40% of women in the United States gain the recommended amount of weight during pregnancy. Excessive weight gain is more prevalent than inadequate weight gain. The Lancet study did not evaluate prepregnancy weight or BMI.

The only truly important pregnancy outcomes are having a healthy infant and a healthy new mom. But, efforts to ensure lifelong health for both start early. A focus on preconceptual health and body weight may be more important than just gestational weight gain. Prevention of childhood obesity needs to include interventions targeted at mother-to-be. Healthy lifestyles that start before a child is even conceived could break the generational cycle of overweight and obesity that is plaguing the world.

References

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