There is little evidence to support any long-term impact of maternal body mass index (BMI) in pregnancy on a child's risk of fatness in childhood and adolescence, according to a new study published in PLOS Medicine by Rebecca Richmond of the University of Bristol, UK, and colleagues. Research has shown that a mother's BMI during pregnancy is associated with greater birth size of her offspring. However, whether this association continues through childhood and is mediated by processes that occur during gestation—such as effects of circulating glucose and lipids levels—had been unclear. In the new study, the researchers used body mass and genetic information on 6,057 mother-offspring pairs from two prospective birth cohort studies. In one cohort, the offspring's BMI was measured around age 6; in the other it was taken multiple times between ages 7 and 18. While the researchers found associations between maternal BMI before pregnancy and offspring BMI at all ages,...