Effects of Infant Diets on Estrogen Activity and Development

Study Summary

This study, conducted at the Children's Hospital of Boston and the Brigham and Women's Hospital in Boston, will examine the natural history of infant development in the first year of life and how different types of infant feeding may affect that development. During pregnancy, babies are exposed to the female hormone estrogen from their mothers. Estrogen affects development of breasts and milk production, as well as the development of the uterus, ovaries and possibly other hormonally responsive organs in both males and females. Between 6 and 12 months of age, the effects are reduced. Breast milk and some infant formulas may contain compounds that can act like female hormones in the body and may prolong the estrogen effects. This study will examine the natural history of estrogen activity in infants on different feeding regimens, breast milk, cow's milk, and soy milk and will serve as preparation for a larger study of the effects of soy formula on estrogen activity in infants. Full-term female babies (37 to 41 weeks gestational age at birth) from 0 to 12 months of age and male babies from birth to 6 months of age who weigh from 2501 to 4499 grams (about 5.5 to 10 pounds) at birth and who have no chromosomal abnormalities, major malformations, or endocrine problems may be eligible for this study. Males must have palpable testes. Babies being fed a diet of breast milk, soy milk, or cow's milk will be included. Study procedures include the following: * History of the baby's dietary intake since birth, provided by the parent; * Ultrasound measurement of the uterus, ovaries, and breasts in female babies; the testes, prostate, and breasts in males; and the thymus, thyroid, and kidneys in all babies; * Measurements of all babies' weight, length, and head circumference.