A common diabetes drug can improve the chance of success for some women undergoing IVF, say UK researchers.
Metformin is used to treat diabetes
A hormonal disturbance called Polycystic Ovarian Syndrome (PCOS) is one of the leading causes of infertility in women.
Even with IVF, many women with PCOS will still be unable to have a baby.
Doctors from Leeds General Infirmary told a European fertility conference how metformin can double the chance of IVF success for these women.
Mr Adam Balen and colleagues recruited 94 women with PCOS seeking IVF to help with fertility problems.
They gave half of the women metformin and the other half a
Metformin increased the chance of an ongoing pregnancy - beyond 12 weeks gestation - from 20% to 40% compared to placebo.
"This is the first study to show such a significant effect in women undergoing IVF," Mr Balen told the European Society of Human Reproduction and Embryology in Copenhangen, Denmark.
Metformin is already commonly used to treat PCOS - a condition affecting up to that up to one in four women.
If the woman is overweight, the symptoms are often worse and they will tend to have higher than normal levels of the blood sugar regulating hormone insulin.
Sufferers may have some or all of the following
Amenorrhea (no menstrual period)
Multiple, small cysts in the ovaries
Obesity or weight gain
Increased levels of male hormone
Insulin causes the ovary to produce the male hormone testosterone which can impair fertility.
Metformin works by lowering insulin levels, thereby lowering testosterone levels which means the ovary can begin to work more efficiently.
IVF can help women with PCOS conceive but these women are at a greater risk of a rare but potentially fatal side effect of IVF, called Ovarian Hyperstimulation Syndrome (OHS).
Not only did metformin increase the chance of ongoing pregnancy, it also reduced the risk of OHS.
With placebo the risk was 20% where as the risk with metformin was only 3%.
Mr Baden said: "We are getting more pregnancies and less hyperstimulation so it's an all round benefit.
"Metformin is very safe, even in pregnancy, and has been used for diabetes for 40 years.
"More and more people have been using it for PCOS, but it has not been established for women with PCOS undergoing IVF. Our data may well change that."
His team at Leeds now gives metformin to all women with PCOS undergoing IVF routinely, based on the findings.