Women invited to trial twice-a-year contraceptive jab

Trials to test the effectiveness of a six-monthly contraceptive injection for women are to start in Lothian and Ayrshire.

Women invited to trial twice-a-year contraceptive jab

If successful, the study will expand the range of contraceptive options available to women, giving them greater choice over how to control their fertility.  

Some 750 volunteers between the ages of 18-35 years will take part in the study across four countries, using a contraceptive injection of depot medroxyprogesterone acetate (DMPA), similar to the existing injectable method.  

Contraceptive injection 

In the study, women will receive an injection of DMPA under the skin every six-months.  

The contraceptive injection is used by 15 per cent of women in the UK, and currently involves injecting DMPA into the muscle on a three-month basis.  

DMPA contains the hormone progestogen, which acts to prevent pregnancy by stopping the release of the egg from the ovary. It also thickens the cervical mucus, which makes it difficult for sperm to access the womb. 

More convenient 

Researchers say the new method provides a more convenient option for delivery, with women required to attend two appointments a year for an injection instead of the four currently needed.  

This could also lead to increased effectiveness – having to inject less frequently should reduce unintended pregnancy due to missed or late injections, experts say.  

Many benefits 

Side effects could also be improved. The drug is absorbed more slowly when injected under the skin instead of into the muscle, resulting in a gentler peak in hormone levels. 

Moving to two injections per year would reduce the amount of DMPA injected by half. This could lead to a more rapid return of fertility after stopping the contraceptive and further improvements to side effects, according to scientists. 

Global study 

The University of Edinburgh trial will be part of a global study that builds on previous research of 21 women that showed that DMPA stopped all participants from ovulating - releasing eggs - for at least six-months when it was given under the skin. 

Before joining, study participants will be examined and have their blood tested to check they can take part. All participants will have scheduled follow up visits to check their progress for the full 13-month study duration.  

Volunteers will also be required to undertake pregnancy tests each month, with a check-in phone call to follow up on results. 

People who would like to take part can register their interest by contacting the study team in Edinburgh at, or Ayrshire at

This trial of a new contraceptive method, designed to be taken twice a year rather than the current four-times a year, could potentially offer meaningful benefits to many women around the world who are taking birth control. As it is injected under the skin instead of into a muscle, DMPA will last twice as long in the body, thereby offering a more convenient option and potentially fewer side effects compared to the current dosage regimen.

Professor Sharon CameronNHS Consultant Gynaecologist and Honorary Professor at the MRC Centre for Reproductive Health

Related links

MRC Centre for Reproductive Health

Study medicine at the University of Edinburgh

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