A New Birth Control Method for Men
It used to be that if a man wanted to take control his reproductive life his choices were limited to vasectomy, condoms, withdrawal, or celibacy. That may be about to change as Chinese researchers test the effectiveness of testosterone shots as an alternative method of birth control for men.
In a recent study, 1,045 Chinese men between 20 and 45 years of age were given testosterone injections for over two years. All these men had fathered a child within the last two years and their partners did not report any fertility problems. Yet these shots where able to prevent pregnancy 99% of the time, coming close to the success rate of female hormonal contraceptives.
The men in the study were given a monthly injection of a formulation of testosterone undecanoate in tea seed oil. Testosterone undecanoate shots have been used worldwide for the treatment of hypogonadism (low testosterone) in men and, in some cases, have been prescribed to improve male fertility by first reducing sperm count with the assumption that once the shots ceased that the sperm count would rebound to higher levels than before (this assumption has been challenged by contemporary fertility specialists).
It seemed to me counterintuitive that the same male hormone used by some men to improve sexual function and sperm count in fact reduces or shuts down sperm production, so I looked for answers on internet and found this explanation of how testosterone affects sperm count from Dr. Perloe, a licensed practitioner of Reproductive Endocrinology and Infertility:
“Sperm production is driven by hormonal stimulation from the pituitary gland. FSH and LH (follicle-stimulating hormone and luteinizing hormone) are released and stimulate sperm production from the testicle as well as testosterone. As testosterone rises, a feedback loop comes into play and the pituitary gets the message that it is doing its job well enough and stops driving the testicle and no longer releases FSH and sperm production drops. It is sort of like giving a woman estrogen and birth control pills. In that case the pituitary gland stops producing FSH and ovulation does not occur.”
Doctors have known about this effect for years. In fact, testosterone undecanoate shots for use as a birth control method for men were first tested back in the nineties but in those early studies a different formulation was used that required weekly, rather than monthly, shots. Since these shots are administered intramuscularly, often in the buttocks, this method of birth control was considered by many potential marketers to be too inconvenient—literally, a pain in the ass.
However the newer oil-based formulations currently being tested allow the testosterone hormone to be released slowly, over a longer period of time, which allows for a monthly, rather than a weekly, shot. Tenderness at the site of injection is the one of the most common side effects reported in the Chinese study—other side effects included acne and increased sex drive in some men. Doctors involved in the study caution that more testing is needed to determine the long-term effects of testosterone injections on men’s hearts and prostate glands and the behavioral effects of testosterone shots.
It is important to emphasize here that all the men in Chinese study had fathered at least one child and, when the shots were terminated at the end of the study, the fertility levels of the participants returned to normal level within three to fifteen months in all but two of the men who completed the trial. It appears that in most cases, sperm count recovers to normal baby-making ranges, making this method ideal for those who want a reliable but not a permanent method of birth control.
Currently this type of shot is being tested in large-scale human clinical trials. This is normally the last stage of testing before a drug is approved for the market. If approved for wider use, this method of contraception promises to be a relatively safe alternative for those men who want to be solely responsible for birth control but for whatever reason are not prepared to undergo a vasectomy or don’t want to deal with the mess and worry of the alternatives. It is unclear at this stage in the process what the cost, and logistics of delivery to the user, will be.
For those who want to go straight to the source, the Chinese study titled “Multicenter contraceptive efficacy trial of injectable testosterone undecanoate in Chinese men” is being published the June 2009 issue of the Journal of Clinical Endocrinology & Metabolism.
Copyright Laura S. Scott. Published 1 June 2009 in Features.
Reader comments
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I don’t think I’d be using testosterone for birth control, there is a link between it and prostate cancer. Oh for a reliable, reversable vasectomy (I’ve had a vasectomy ages ago, but it’d be great for guys who want children later but don’t want to get ‘ooops’ed).
permalink — 2 June 2009, 05:02
I don’t know about other women out there but I sure as hell would not want to leave my reproductive destiny up to any man. We are all in charge of our own bodies and should take steps to protect ourselves if we do not want to get pregnant. It’s great for men who don’t want to have children, however. Too many many men are “oops’d” into fatherhood.
permalink — 1 July 2009, 07:41