Male Contraception Research

Male contraception, or birth control, keeps sperm from coming into contact with an egg to avoid pregnancy. There are two approaches currently available to do this:

1. Blocking the sperm from entering the vagina (as with condoms)
   
2. Keeping the sperm from coming out of the penis (vasectomy/sterilization)

In addition, scientists are researching the development of a male birth control pill. Research for a male birth control pill comparable to the female birth control pill is focused on three approaches:

1. Keeping the male from producing the sperm (hormonal contraception)
   
2. Keeping the sperm from swimming (inhibiting sperm motility)
   
3. Preventing the sperm from fertilizing an egg (interfering with membrane integrity.

This means that the male birth control pill will be a systemic method of contraception – affecting many body systems.

Researchers have conducted studies on two types of systemic birth control for men: hormonal male contraception and immunocontraception. Hormonal male contraception uses hormones (injected, implanted, or taken orally) to stop sperm production, but this would reverse when the contraception is no longer used.

Immunocontraception is a birth control method that uses the body's immune system response to prevent pregnancy. Although this is a viable option for many animal species, scientific interest in use by human subjects has recently declined because research does not show a reliable decrease in fertility among male subjects.

• Different Types of Male Contraception
• Differences From Female Birth Control
• How Advanced Is The Research?
• Does It Protect Against STIs?
• Does It Protect Against Pregnancy?

Different Types of Male Contraception

At least four types of hormonal male contraception are currently being tested: testosterone, androgen/progestin combination, testosterone/GnRH combination, and selective androgen and progestin receptor modulators.

All four methods of hormonal birth control try to stop or slow sperm production by interfering with some step in the sperm growth cycle. This creates a low sperm count, which could be reversed when the male stops using the contraceptive.

Androgen – a type male sex hormone that influences the male reproductive system – inhibits sperm production by suppressing the pituitary gland's secretion of hormones. These pituitary hormones (LH and FSH) are the signals required for normal sperm production. Without them, sperm do not form properly.

The androgen/progestin combination indirectly increases testosterone levels. (Testosterone is a male sex hormone that controls sperm development.) Increasing the testosterone slows the sperm production by suppressing the LH and FSH released from the pituitary gland.

GnRH also suppresses pituitary hormones, and thus, reduces sperm count. Finally, androgen and progestin receptor modulators slow sperm production by changing the shape of the molecular receptors that bind androgen and progestin so that the male reproductive cells will not correctly produce sperm.

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Differences From Female Birth Control

Obviously, male and female reproductive systems are very different. Many birth control methods available to women do not work for men. For example, men cannot use intrauterine devices, also known as IUDs, because they do not have uteruses in which to implant the IUD.

Currently, most female contraceptives are oral medications. The majority of male birth control options presently being researched are injections. Many of these medications must be taken often as weekly injections. Although Depo-Provera is an injectable birth control option for women, it is only needed once every three months.

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How Advanced Is The Research?

Currently, the most promising approach to hormonal male contraception is the combination of testosterone and progestin. There is ongoing research to test the drug's effectiveness, evaluate its safety, and monitor the side effects in 1,000 men in China.

Many researchers believe a daily male birth control pill could be on the American market within five to seven years. Injectable or implantable male contraception may be available even sooner.

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Does It Protect Against STIs?

No. Only barrier methods such as male condoms, female condoms, or dental dams can prevent sexually transmitted infections (STIs).

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Does It Protect Against Pregnancy?

Yes. When used correctly, this type of contraception is meant to lower sperm count to the point where it is nearly impossible to become pregnant.

Since all hormonal male birth control methods are currently in the testing phase, there is no comprehensive data on the efficacy of these methods.

However, in one androgen-only study, pregnancy rates were 0/250 person-years for men with no sperm in the ejaculate, and 4/50 person-years for men with a very low sperm count. This means that only four out of 300 men, or 1.3 percent, were able to get a woman pregnant while using male birth control.

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