WOMEN who are not overweight and lose significant weight between their first and second pregnancies could have a greater risk of a premature birth.

It is according to research by University of Southampton, which found that one in a hundred women who have a body mass index between the recommended range of 18.5kg/m2 and 24.9kg/m2 lost significant weight between pregnancies.

Although ill general health or stress could also lead to both weight loss and premature birth, researchers said these findings could help midwives and other health professionals identify women who may have greater odds of premature birth.

Dr Alwan, from the faculty of medicine at the University Of Southampton, led a team who studied data from 2003 to 2018 of around 15,000 women receiving antenatal care and lived in Southampton and surrounding parts of Hampshire during at least two of their pregnancies.

As well as studying the mothers’ weight, they looked at factors such as education, employment and smoking.

Women who gained significant weight by the start of a second pregnancy were more likely to be smokers, unemployed, with lower educational attainment and a longer interpregnancy interval.

Researchers found losing weight was much less common than gaining weight between pregnancies, with half of all women gaining weight between their first and second pregnancies compared to under one in six women who lose weight during that period.

They therefore recommend that the best situation is to be within the recommended body mass index of between 18.5kg/m2 and 24.9kg/m2 at the start of each pregnancy.

Dr Nisreen Alwan said: “The period between pregnancies is a key window of opportunity to improve health given the close contact families have with health and care professionals, but there has been little research into effective ways to help mothers maintain a healthy weight in this period.”

“It is standard practice to weigh mothers at the start of pregnancy and a comparison to their weight at the start of previous pregnancies could flag up any risks, giving mothers and health professionals the chance to take steps to improve pregnancy and later health outcomes.”