Drug Study Finds Lesbian Link -- Women Were Exposed To Synthetic Estrogen While In Womb

NEW YORK - Women who took the synthetic estrogen DES when pregnant were more likely to have daughters with bisexual or homosexual tendencies, according to a newly published study by a Columbia University psychologist.

Experts said the finding had important implications for two closely related controversies in science: Does biology play a major role in determining sexual orientation? And, are estrogen-mimicking man-made chemicals having powerful effects on people?

"This is potentially a very significant finding," said Bruce McEwen, director of the laboratory of neural endocrinology at Rockefeller University in Manhattan and an expert on hormonal effects on the brain. "This really is a bold hypothesis, but it is a credible hypothesis."

Researchers found that eight of the 117 DES daughters studied had bisexual or homosexual tendencies, while none did in a carefully selected 117-woman control group.

"It is a mild increase, but it is statistically significant, and it was repeated in all the subgroups we studied," said the study's lead author, Dr. Heino Meyer-Bahlburg, a professor of clinical psychology at the College of Physicians & Surgeons of Columbia University. The research was reported in January's Developmental Psychology.

Women who were exposed to DES in their mothers' wombs were compared to their unexposed sisters, to unexposed women with gynecological problems similar to those caused by DES and to a healthy control group. In each case, psychological tests developed by sex researcher Alfred Kinsey showed that the DES women were significantly more likely to have homosexual or bisexual tendencies, according to the Columbia study.

The results suggest that while exposure to estrogenic chemicals in the womb is not the dominant cause of homosexuality, it may be one of many causes - some inborn and some learned, Meyer-Bahlburg said.

DES, or diethylstilbestrol, was widely prescribed to pregnant women as an anti-miscarriage drug for more than 20 years, until it was banned in 1971 for causing vaginal and cervical cancers in female offspring, among other health problems.

It is considered too dangerous today to give people similarly massive doses of estrogenic hormones, so studying DES sons and daughters is the only way to determine the effects of powerful estrogens on human development.

Several gay groups declined to comment on the Columbia study.

Meyer-Bahlburg has also studied DES sons and found no increase in homosexuality or bisexuality.

But the increase among DES daughters is consistent with what researchers know about the fetal brain, experts said.

Scientists know that the brains of female fetuses, unlike male ones, have a protein that blocks natural estrogens. But DES and other man-made estrogens don't bind with that protein so they enter the fetal brain and theoretically trigger a process of masculinization that influences sexual orientation.