A high estrogenic environment in utero may increase subsequent breast cancer risk. It was therefore determined whether a maternal exposure during pregnancy to the phytoestrogen genistein, which exhibit estrogenic activities in vitro and in vivo, alters breast cancer risk among female offspring. The results indicate that in utero exposure to genistein, dose-dependently increased the incidence of breast tumors, when compared with the controls. The number of estrogen receptor binding sites was significantly elevated in the mammary glands of genistein offspring.

Oncol Rep 1999 Sep-Oct;6(5):1089-95

Dr. Mercola's Comment:

If you have not read the soy article by Dr. Enig in my article section at www.mercola.com, I would encourage you to do so. This is another reason that soy should not be consumed by most of us. It is even worse to provide soy formula for the same reasons. The phytoestrogens in soy are potent hormonal influences and can profoundly adversely affect the health of infants.

This does not even factor in the issue of aluminum contamination as soy formula has ELEVEN times as much as aluminum as regular formula.

Obviously, breast milk is best. But for many reasons, breast milk is not always an option. If one is forced to use a commercial formula, I find that the Carnation product Good Start (for under six months) is one of the best. It is from milk, but hydrolyzed about 80%, which helps reduce the allergenic side effects tremendously.

However, the take home message from this study is to avoid soy, especially if you are a pregnant woman. Just remember that the edible oil industry is a 70 billion dollar enterprise and they fund many studies to show the benefits of soy so that you will consume it. Their goal is to sell more domestic soy. Their goal is NOT your health.  Also, one half of the soy grown in this country is genetically modified and we have no idea what type of complications that might result in.