Multiple birth differences found

The study looked at almost 500 women who were expecting twins

A treatment which prevents premature births in single pregnancies may be ineffective in women expecting more than one child, research has shown.

The study, led by an Edinburgh University researcher, suggests a difference in the way the births occur with single and multiple pregnancies.

The findings could pave the way for treatments to delay early multiple births.

The study looked at almost 500 women around the country expecting twins.

These pregnancies account for more than 98% of multiple births in the UK.

Understanding the differences between what happens in premature births in singleton and multiple pregnancies can help us improve treatments Prof Jane Norman Edinburgh University

It is hoped the findings, published in The Lancet, will help lead to improvements in treatment to prevent premature births in women expecting more than one child and help researchers understand how the process of premature labour may be different.

Half of the women in the study group were given progesterone gel - a hormone which helps protect the lining of the womb - while the other half were given a dummy version.

The gel treatment has been shown to reduce early births in women expecting one child considered at high risk of early labour, including those who had previously given birth prematurely.

However, researchers found that contrary to single pregnancies, the hormone gel did not reduce rates of premature births in those expecting twins.

Effective strategies

Professor Jane Norman, director of Tommy's Centre for maternal and fetal health research at Edinburgh University, said: "While the study looked at twins, it suggests that the biological process of premature births in women with multiple births is different than in women expecting one child.

"Understanding the differences between what happens in premature births in singleton and multiple pregnancies can help us improve treatments and also address the higher incidence of premature labour in multiple pregnancies."

Professor Norman, who is also a consultant obstetrician at the Simpson's Centre for reproductive health at the Royal Infirmary of Edinburgh, said that about 20% of multiple pregnancies resulted in pre-term delivery before 34 weeks, compared with 2% to 3% of pregnancies for women expecting one child.

Richard Kennedy, secretary general of the International Federation of Fertility Societies (IFFS), said: "This latest research underscores the lack of effective treatments in the prevention of pre-term birth in multiple pregnancy.

"This means that fertility services need to adopt effective strategies for the prevention of multiple pregnancy."

Multiple pregnancies accounted for 1.6% of all births in the UK in 2007, but rates of stillbirths and neonatal mortality are between three and eight times higher than in single pregnancies.