[RobertLS]

http://news.sciencemag.org/scienceno...nt.html?ref=hp




If you're trying to avoid getting pregnant, here's another reason to mistrust the rhythm method of birth control: New research confirms that the fluid in semen, long dismissed as primarily a vehicle for sperm, contains a substance that can trigger ovulation and other pregnancy-supporting hormonal responses in female mammals. The find could lead to new fertility treatments in humans.

Like most female animals, women are spontaneous ovulators, meaning they release eggs on a fairly regular basis regardless of their sexual activity. A few animal species, however, such as camels and rabbits, release viable eggs only in response to sex. These animals are called "induced ovulators." For decades, scientific dogma has held that in induced ovulators, the physical stimulation of sex triggers hormonal responses within the female that lead to the production and release of eggs. In 1985, however, a group of Chinese researchers challenged this idea by suggesting that there might be an ovulation-inducing factor (OIF) in semen itself. According to veterinarian and reproductive biologist Gregg Adams of the University of Saskatchewan in Saskatoon, Canada, the hypothesis ran so counter to common wisdom that "people just ignored it. Me included."


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