LA JOLLA, Calif. -- Scientists Thursday reported successful tests of a powerful synthetic brain hormone that may lead to a 'once-a-month' birth control pill for women that avoids the side effects of current contraceptives.
The same hormone also may reverse infertility in women with a condition known as luteal phase defect, said a research team at the University of California, San Diego.
Dr. Samuel S.C. Yen, chairman of the reproductive medicine department, reported the study in the current issue of Science Magazine.
Researchers said it will take two to three years to conclude further experiments before large-scale clinical trials can be considered.
The pilot two-year study involved 17 fertile women who were given injections of a synthetic version of a natural brain hormone called LRF-agonist (luteninizing hormone releasing factor).
With the hormone the researchers induced a condition known as luteal phase defect, a disorder that causes infertility when it occurs naturally.
The hormone interrupts the delicate synchronization of the menstrual cycle enough to hamper implantation of a fertilized egg in the wall of the uterus.
'Daily analysis of the participants' hormone levels indicated that they developed a luteal phase defect because the corpus luteum, which supplies hormones to the uterus in preparation for implantation, had ceased functioning by the time the eggs arrived,' Yen said.
Yen said the synthetic hormone differs from current birth control pills because it acts on a precise target -- the pituitary cells that produce other hormones that control the ovarian cycle.
The present pills inhibit activities of the hypothalamus, pituitary and ovaries and also act outside of the reproductive system, affecting the liver, gallbladder, and blood clotting system.
None of the 17 women tested experienced side effects from injections of the synthentic hormone, but Yen cautioned that it may take years -- as in the case of present birth control pills -- to determine whether side effects may result.
The advantage of the hormone is that it needs to be taken only only once at the beginning of each menstrual cycle, instead of daily.
Paradoxically, Yen said low doses of the hormone can cure infertility in women whose brains produce insufficient quantities. The team has treated 12 such patients. All have begun ovulating and four pregnancies have resulted.