Hormonal Contraception for Men Shows Mixed Results

Tim Locke

October 28, 2016

Researchers say a hormone contraceptive injection for men is effective at preventing pregnancy – but stopped their trial because of too many side effects.

Contraception for women was revolutionised with the Pill and other hormone based contraceptives. However, for men the options haven’t changed for years – condoms or vasectomies – or the risky method of trying to pull out in time – called withdrawal.

Contraceptive Jabs for Men

The idea of a long-lasting contraceptive for men that is not meant to be permanent like a vasectomy has been researched for around 40 years – but has not gone into general use.

The new study published in the Journal of Clinical Endocrinology & Metabolism looked at using regular hormone injections in men as a contraceptive.

The study was just about preventing pregnancy rather than looking at the wider aspects of a new contraceptive for men – such as whether sex partners would trust men to remember to have the injections.

The other aspect of hormone contraceptives for men that was not addressed is that they are not a method of safe sex – unlike condoms, they do not help prevent sexually transmitted infections. This means that male hormonal methods may be more suitable for a couple in a long-term monogamous relationship who don't want to have children at that time – but might later.

Male Contraceptive Study

Researchers found 320 men to volunteer for the study in 10 centres in the UK and around the world. They were healthy with normal sperm counts, aged 18 to 45, and were in long-term relationships with one female partner for at least a year. The partners were aged 18-38 with no known fertility problems.

The volunteers were given 2 injections every 8 weeks. These were 200 milligram injections of a long-acting progestogen and 1,000 milligrams of a long-acting androgen.

Semen samples were tested after 8 and 12 weeks while the hormones worked to reduce sperm count. Tests were then done again every 2 weeks until the man's sperm count was very low - down to less than 1 million/ml in 2 consecutive tests. This took around 24 weeks – so use of the male contraceptive injection would need to be planned in advance. During this phase the couples were told to use other birth control methods. After that, they then relied on the contraceptive jabs alone to prevent pregnancy, and semen samples were checked every 8 weeks during visits to receive the jabs.

Injections and sperm count tests carried on for up to 56 weeks in this phase.

Once injections stopped, researchers checked that sperm counts recovered to normal levels over a period of time.

There were 4 pregnancies during the trial while couples were relying on the jabs alone. This means they were only slightly less effective at preventing pregnancy than the female contraceptive pill.

Side Effects

The main drawback with the jabs was the side effects they caused, including depression and mood disorders. There was one death by suicide, but this was not found to be due to the contraceptive injections.

The study stopped recruiting volunteers because of the side effects – and 20 men dropped out because of them.

Milder problems included injection site pain, muscle pain, high blood pressure, palpitations and acne. One other change in some men was a higher sex drive – although it had the opposite effect for a smaller number.

Overall there were 1,491 problems reported – but 39% were assessed as not due to the jabs.

Despite the side effects, 75% of the volunteers said they'd be willing to use this method of contraception.

More Research Needed

In a statement, one of the researchers, Dr Mario Festin, from the World Health Organisation in Geneva says: "The study found it is possible to have a hormonal contraceptive for men that reduces the risk of unplanned pregnancies in the partners of men who use it.

"Our findings confirmed the efficacy [effectiveness] of this contraceptive method previously seen in small studies."

However, he admits: "More research is needed to advance this concept to the point that it can be made widely available to men as a method of contraception.

"Although the injections were effective in reducing the rate of pregnancy, the combination of hormones needs to be studied more to consider a good balance between efficacy and safety."

Reaction

UK experts have been reacting to the findings in statements.

Professor Allan Young, a mood disorders expert from King’s College London, says: "This is an interesting and important study which adds to the body of data about hormonal effects on mood, although the findings will need to be replicated. The adverse effects on mood of an injectable combination hormonal contraceptive reminds us that men, as well as women, may be subject to effects of reproductive hormones on mood."

Professor Allan Pacey from the University of Sheffield, says: “There is certainly an unmet need for an effective reversible contraceptive for men, along the lines of the hormonal contraceptive for women."

However, he adds: "The fact that so many side effects were observed in the men who were taking part in the trial is of concern. For a male contraceptive to be accepted by men (or women) then it has to be well tolerated and not cause further problems. For me, this is the major concern of this study. But, it is noteworthy that 75% of the men who took part in the trial would be willing to use this method of contraception again. So perhaps the side effects weren’t all that bad after all."

SOURCES:

Journal of Clinical Endocrinology & Metabolism: Efficacy and Safety of an Injectable Combination Hormonal Contraceptive for Men.

Science Media Centre.

NHS Choices: Combined pill.

 

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