A world first clinical trial will examine whether an everyday antibiotic could help reduce recurrent miscarriage.
Scientists hope it will result in a potential new test and treatment for the condition which causes heartbreak as people endure the loss repeatedly.
It is thought it could help half of women with recurrent miscarriage – about 7,000 couples in England and Wales per year.
Researchers do not know what causes the inflammation in the womb that leads to the rejection of the foetus, but one suggestion is that it could be a lingering infection the woman has picked up.
In some women the lining of the womb (the endometrium) is inflamed, a condition called endometritis.
Experts also suspect endometritis may be caused by an imbalance of the bacteria (microbiome) that live in the reproductive tract.
A healthy endometrium is important for the embryo to be able to attach to the womb and it is thought that endometritis disrupts this process, and can lead to a miscarriage.
Treating endometritis with antibiotics may reduce the condition by reducing disruptive bacteria and allowing the healthy bacteria to grow, scientists say.
Warwick Medical School’s Professor Siobhan Quenby, principal investigator on the trial, said: “This is potentially a new treatment for up to half of people with recurrent miscarriage.
“We know that doxycycline is given to some women experiencing miscarriage in other countries, but there has never been a proper trial conducted.
“And instead of just having your blood tested to look for causes of miscarriage, as is current practice, you will have the lining of the womb tested too so that we can identify those who will benefit from this treatment.
“Our aim is to try to improve the womb before you get pregnant.
“Most miscarriages occur within the first trimester – 12 weeks – of pregnancy and our aim is to see a reduction in these early miscarriages.”
The research will be conducted by the University of Warwick in partnership with University Hospital Coventry and Warwickshire NHS trust.
It will investigate whether a course of antibiotics prior to conceiving could reduce the likelihood of miscarriage in up to 50% of cases.
The Chronic Endometritis and Recurrent Miscarriage (CERM) trial aims to discover whether using the antibiotic doxycycline – often used to treat chest and skin infections – in women with the condition endometritis can improve their chances of having a baby.
In America and Germany the antibiotic is already used to treat recurrent miscarriage by improving the balance of bacteria present in their reproductive system.
Prof Quenby will be the first to examine the effectiveness in a clinical trial.
Speaking at the British Science Festival, being held in Coventry and Warwickshire, she described the emotional toll recurrent miscarriages take on the parent, highlighting how they grieve for the lost child.
She explained: “What you have lost is hope of the future, which is the same as any grief.
“What I get frustrated about is ‘just because you have been pregnant for a month, it doesn’t count’.
“A miscarriage is a grief reaction – it is normal to grieve, it is normal to be sad.”
Prof Quenby added that often people are left feeling there is nothing they can do, and the trial offered them a positive course of action.
She said they would “rather have a placebo than sit at home and suffer”.
The trial has received £1.9 million in funding from the Efficacy and Mechanism Evaluation (EME) Programme and will involve more than 3,000 women in NHS hospitals in the UK who have recurrent miscarriage.
Professor Quenby added: “The special trial design means that we can answer a series of questions rather than just one as in a traditional trial.
“We will investigate what degree of inflammation is needed to cause miscarriage, how does inflammation cause miscarriage, does doxycycline reduce inflammation, does doxycycline alter the microbiome, does doxycycline reduce miscarriage, does doxycycline increase the number and time taken to achieve a live birth.”