What is male contraception?
Male contraceptive methods are those men undertake in order to prevent pregnancy.
Currently available methods
The condom is a form of barrier contraception that stops sperm from meeting an egg and offers additional protection against sexually transmitted infections.
A vasectomy is a minor surgical procedure that involves either cutting or blocking the tubes that carry sperm (called the vas deferens). It therefore prevents sperm meeting the semen that forms the ejaculate, and so acts as a contraceptive. Together, these methods comprise the only currently available contraceptives for men.
The future: Hormonal methods
For several decades, there has been ongoing research into hormonal contraceptives for men. Sperm production is controlled by reproductive hormones. The hypothalamus is a part of the brain that secretes a hormone called gonadotrophin-releasing hormone (GnRH). This acts on another gland within the brain called the pituitary gland, resulting in the secretion of two further hormones, luteinizing hormone (LH) and follicle stimulating hormone (FSH). These hormones travel in the blood stream to the testes where they act to cause testosterone production, which also supports sperm development.
The production of testosterone is under the control of a negative feedback loop such that when testosterone levels are high, GnRH and gonadotrophin secretion is reduced. Hormonal contraceptive methods exploit this negative feedback loop to suppress sperm production.
Initial attempts at using hormonal approaches to achieve male contraception included injection of high doses of testosterone, which by causing negative feedback on the hypothalamus and pituitary gland, acts to suppress GnRH and gonadotrophin secretion. This will result in a reduction in sperm production sufficient to prevent pregnancy. However, the high doses of testosterone required were associated with several side effects, such as acne, and additionally multiple injections were not desirable for patients. More recent developments have therefore attempted to address this.
Progesterone is a hormone that naturally exists in men in small amounts. However, at higher doses it is also able to suppress secretion of GnRH and gonadotrophins. By combining progesterone with low dose testosterone, sperm production is suppressed by the progesterone, whilst also providing physiological levels of testosterone. This results in a reduction in side effects, such as low libido. Initial studies investigated the use of a combination of an oral progesterone tablet with a topical testosterone gel. However, most recently, Phase IIb clinical trials (which confirm efficacy before moving to the final phase of testing) have been initiated investigating the use of a gel which has a combination of both progesterone and testosterone. This gel is applied to the skin, and acts to suppress the production of sperm without affecting libido. Although the gel requires daily application to ensure suppression of reproductive hormones, and is a reversible form of contraception, it has a long duration of action meaning that its contraceptive effect can be preserved even if doses are missed. Whilst is currently too early to determine whether this hormonal combination (known as NES/T) will reach the market, early reports from the study have been promising.
The future: Non-hormonal methods
In addition to hormonal methods, there is ongoing research into non-hormonal alternative methods of male contraception. These include the injection of a non-toxic chemical into the vas deferens in a procedure called ‘reversible inhibition of sperm under guidance’ (RISUG). The non-toxic chemical stimulates a local reaction that results in the blockage of the vas deferens, thus preventing any sperm entering the ejaculate. Furthermore, this non-toxic chemical additionally damages any sperm that comes into contact with it. The effects of this chemical can then be reversed by injecting a further substance that washes it out. Additional research is needed to determine the long-term effects of RISUG, however it has potential as a future contraceptive option for men that is reversible. An alternative to RISUG involves the insertion of a device into the vas deferens, called an intra-vas device (IVD). This device is inserted under local anesthetic, and acts as a physical filter for sperm, preventing them entering the ejaculate. The IVD could then be removed when contraception was no longer required.
Are there any side-effects to male contraception?
Condoms are not associated with any side effects and when used correctly, are 98% effective at preventing pregnancy.
A vasectomy is a day-case surgical procedure. Men may experience pain for several weeks afterwards. It is considered a permanent form of contraception and is >99% effective at preventing pregnancy. Whilst it is possible to attempt reversal, this is not always successful. Given this, it is important that patients consider carefully whether they may want any future children before undergoing the procedure.
High-dose testosterone may be associated with acne and weight gain, although the lower doses of testosterone used in the most recent studies have fewer side effects. However, as hormonal contraceptives are not yet licensed for use, their full side effect profile remains to be determined.
Related websites
British Association for Sexual Health and HIV