Overweight women 20% more likely to miscarry

BEING overweight could increase the risk of suffering repeated miscarriages by more than a fifth, scientists have found.

An estimated one in four pregnancies here end in miscarriage, and up to 3% of Irish women suffer numerous subsequent losses. And now a study has found an increased risk of consecutive miscarriages among those who are overweight.

The review of 16 studies found that women who were overweight, with a body mass index (BMI) above 25, had a 21% higher risk of suffering at least two miscarriages in a row.

This higher risk was compared to women of a healthy weight. Experts have suggested that being overweight may change the environment within the womb.

Experts have stressed that recurrent miscarriages are still rare and around one in six women who have had three or more of them go on to have a successful pregnancy. And they said women who are already pregnant should not try to lose weight but should eat well. However, the evidence has suggested the importance of trying to achieve a healthy weight before trying to conceive.

The review also looked at the odds of further miscarriages in women who had already had at least two and found the risk was 77% higher in those who were obese. Dr Bonnie Ng, lead author of the study from Southampton University, said: ‘We need to focus on helping women manage their weight, to bring it within the normal BMI range, if they are planning a pregnancy or have a history of pregnancy loss. This will reduce the potential risk of pregnancy complications such as miscarriage.’

The cause of recurring miscarriages is ‘unexplained’ in half of cases which prompted the team to investigate lifestyle causes including weight, smoking, alcohol and caffeine. Researchers also found that in women who have already had repeated miscarriages, those who are overweight have a 35% higher risk of suffering another.

There are several reasons why overweight women may be at greater risk of repeated miscarriages, but some experts suspect fat in the body disrupts signalling between the cells in the womb and those of the embryo and placenta, so the unborn baby does not develop as well.

The review was published in the journal Scientific Reports and was based on a relatively limited level of evidence from studies, rather than ‘gold standard’ randomised controlled trials.