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New study casts doubt on 'rhythm method' of birth control


The "rhythm method" —long espoused as a "natural" means of birth control— may not be all that effective.
 
This is based on the latest findings published in the Aug. 28 issue of the Proceedings of the US National Academy of Sciences.
 
The study, led by veterinarian and reproductive biologist Gregg Adams of the University of Saskatchewan in Saskatoon, Canada, confirms that seminal fluid also contains a substance that can trigger ovulation and other pregnancy-supporting hormonal responses in female mammals. In other words: unprotected sex, even during the supposedly "safe" period before ovulation, may actually hasten ovulation —and pregnancy.
 
Induced vs spontaneous ovulation
 
Previously, only a few animal species, like camels and rabits, were considered to be "induced ovulators." These animals release eggs only in response to sex.
 
Human females, on the other hand, have long been thought to be "spontaneous ovulators." This means that they release eggs on a regular basis, regardless of sexual activity.
 
However, the new study's findings run against this common wisdom. It seems that the male does indeed play a part in female ovulation, and that engaging in unprotected sex can trigger ovulation.
 
Ovulation-inducing factor
 
In 1985, a group of Chinese researchers hypothesized that there might be an ovulation-inducing factor (OIF) in semen itself.
 
This served as the take-off point for Adams' research. His colleagues injected the seminal fluid of male llamas —a mammal closely related to camels— into the hind legs of female llamas. Much to their surprise, Adams said, "[I]njecting seminal fluid into the female llamas' bloodstream had a very potent ovulatory effect."
 
The OIF, according to the study, travels into the bloodstream of females, causing the body —the hypothalamus and pituitary gland, in particular— to release hormones required for pregnancy.
 
Adams' team dug deeper to find out which component of semen stimulates ovulation.
 
After all, Adams said, "Sperm make up only about 5 percent of semen."
 
Common protein
 
Adams' team found that the culprit is neural growth factor (NGF), a common and well-known kind of protein long associated with nerve development.
 
"We were looking for an unknown protein," Adams said.
 
But NGF or OIF is found throughout the body in a lot of species —including humans.
 
"I didn't know whether to be happy or sad about that," Adams quipped.
 
His team examined not only llamas, but a number of other species, including boars, rabbits, stallions, mice, and humans.
 
After this, the team intends to study the relationship between NGF and human infertility. Adams also said that perhaps OIF treatments could be developed for couples having a difficult time getting pregnant. — TJD, GMA News