Mary Broadfoot inquired about breastfeeding vs bottle (ABM) feeding and its relation to timing of sexual development. This research was reported in the Proceedings of the National Academy of Sciences on May 24, 1994. The research was done by Dr. Yitzhak Koch and his colleagues at the Weizmann Institute of Science in Rehovot, Israel. I did not read this report, but a description of it in an article in the N.Y. Times that day, written by Natalie Angier, in the "Science Times" section, p. B5, and titled, "Mother's Milk Found to Be Potent Cocktail of Hormones." I hope this is enough information to allow you to track it down. The research was conducted in rats and was recognized as the first detection of a neural hormone being synthesized in the breast gland itself instead of in the brain or elsewhere and then secreted into the milk. Angier states, "What exactly the hormone does for a suckling infant remains unclear, but researchers propose that it influences the development of the newborn's sex organs, forstalling their maturation until the offspring is ready for reproduction..." It is an interesting article. We did have a discussion of this on Lactnet this fall sometime, but I am not sure which month. Anne Altshuler, RN, MS, IBCLC and LLL leader in Madison, WI