While many health agencies, including the Centers for Disease Control and Prevention, tout the benefits of breastfeeding babies for at least 6 months to reduce the likelihood of childhood overweight, the positive effects do not appear to last into adulthood. The authors studied over 35,000 nurses working in the United States for 12 years. Their mothers were sent questionnaires asking about breast- and bottlefeeding, and about the type of milk or milk substitute given in the bottle. The participants were asked about their body shape at ages 5 and 10, weight at age 18, and current weight. Results showed that the duration of breastfeeding, including breastfeeding only, was not related to being overweight during adulthood. Women who were exclusively breastfed for more than 6 months had a 0.94 risk of becoming obese as adults compared with women who were not breastfed. Women who were breastfed for more than 6 months had a leaner body shape at 5 years of age compared to women who were not breastfed or breastfed for less than 1 week, but this result did not last until adulthood. The authors concluded that while breastfeeding is of benefit to the health of the mother and baby, it does not have a lasting impact on obesity.