The time between pregnancies is a ‘crucial period' for obese women to lose weight, a new study has found.

Obese women who become pregnant have an increased risk of suffering a range of health risks, including pre-eclampsia (high blood pressure) and gestational diabetes. They are also more likely to require medical intervention, such as induction or a Caesarean section.

Obese women also tend to have larger babies and these babies are more likely to have health problems such as low blood sugar and jaundice. They are also more likely to become obese in childhood.

A study carried out in the Coombe Maternity Hospital in Dublin in 2010 found that almost half of all pregnant women in Ireland are overweight, while 15% are obese or morbidly obese.

However, according to US scientists, the time between pregnancies is a golden opportunity for obese women to lose weight. Obese women should also be encouraged not to gain excessive weight while pregnant.

"This data suggested that the interval between pregnancies is a crucial period for obese women to lose weight. In addition, the pregnancy and postpartum periods provide a unique opportunity for behaviour change because healthcare professionals are well positioned to counsel women," explained lead scientist, Dr Arun Jain, of St Louis University.

The study involved an analysis of the records of almost 10,500 women who gave birth to their first two babies between 1998 and 2005.

It found that those who lost weight after the birth of their first child were more likely to go on to have a normal sized baby compared to those whose weight increased or stayed the same.

Furthermore, the results indicate that the women did not have to lose huge amounts of weight to make a difference. For example, an obese woman who was five feet, four inches tall, who lost just under 12lbs between her first and second pregnancy, was much less likely to have a large baby the second time around compared to an obese woman who stayed the same or gained weight.

Dr Jain described this as ‘an achievable weight loss that provides the next generation with a healthier start to life'.

On the other hand, obese women who gained weight between pregnancies significantly increased their risk of having a larger baby. And overall, the study found that the women did tend to gain weight with each pregnancy. One in four was severely obese during their first pregnancy, but this rose to one in three for second pregnancies.

The rate of morbid obesity also rose.

"In our study cohort, women who gained more weight in their first pregnancy were heavier in the beginning of their second pregnancy and more likely to deliver a big baby.

"Based on the findings of our study, patients should avoid excessive weight gain during pregnancy and be counseled that losing weight between pregnancies may decrease the risk of adverse maternal and foetal outcomes. You and your child are likely to benefit," Dr Jain added.

Details of these findings are published in the American Journal of Obstetrics and Gynecology.

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