Babies of women who were obese before becoming pregnant are at TWICE the risk of dying in infancy

Women who are obese when they become pregnant are at twice the risk of their baby dying before the age of one, experts have warned.

Losing weight prior to trying for a baby, and only gaining a healthy amount of weight while expecting, 'significantly' reduces the risk of the baby dying in infancy.

Experts say the findings highlight the need for a comprehensive approach to reducing obesity among women of a reproductive age.

They say weight counselling before conception and during pregnancy, could be key.

Lead author of the study, Dr Lisa Bodnar, an associate professor at the University of Pittsburgh, said: 'One in three women start pregnancy at an unhealthy weight and more than half of women gain either too much or too little weight during pregnancy.

'While more research needs to be conducted, we are hopeful that this study can be used to start a dialogue between physicians and women on the importance of not only gaining a healthy amount of weight while pregnant, but also reducing excess weight before they become pregnant as a potential way to improve infant survival.' 

Every year, around 24,000 infants die in their first year of life in the US.

The rate of infant deaths in America, of 6.1 deaths per 1,000 live births, ranks 26th in the world, despite a 20 per cent decline in the US infant mortality rate from 1990 to 2010.

Dr Bodnar and her colleagues examined records from more than 1.2 million live births in Pennsylvania from 2003 to 2011.

Among them were 5,530 infant deaths - defined as the death of a baby before his or her first birthday.

The mothers were all classified as underweight, normal weight, overweight or obese, which was divided into three grades, based on their pre-pregnancy body mass index.

In each weight group, the researchers also examined the impact on infant mortality when women gained significantly more or less weight during pregnancy that Institute of Medicine guidelines.

The guidelines, for example, recommend a weight gain of 25 to 35 pounds for normal-weight women and 11 to 20 pounds for obese women.

In all the weight groups, except the most obese, gaining less than or much more than recommended weight increased the risk of infant death.

However, even when obese women gained the optimal weight during pregnancy, their risk of infant death was still about twice as great as that of women who began pregnancy at a normal weight.

Study co-author, Dr Katherine Himes, an associate professor at Pitt's Department of Obstetrics and Gynecology, said: 'Obesity and infant mortality are among the most critical public health issues today.

'Our study highlights the importance of discussing weight loss with obese women prior to pregnancy because losing weight during pregancny may increase the risk of her baby dying.

'We hope this information empowers providers, including obstetricians, family doctors and primary care physicians, to discuss the benefits of preconception weight loss with all obese, reproductive-age women.'

The findings are published online and will appear in the February issue of the journal Obesity.

The research was funded by the National Institutes of Health.  

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