A woman who is both over weight and pregnant faces double challenges, not least because many women who are not overweight struggle not to gain weight over the course of the nine month gestation period.

Pregnant women who are overweight or obese can have serious health risks including high blood pressure, pre-eclampsia, diabetes and premature birth, but there is good news. A study published today on bmj.com shows that these risks can be mitigated by following a healthy calorie controlled diet over the course of the pregnancy. With the infamous cravings, this might prove more difficult in practice, nonetheless the benefits are proven.

The article outlines quite shocking figures, showing that more than half the women in the UK are are overweight or obese, while more than 40% of women in the US and Europe gain more than the recommended weight while pregnant. While some girls like to assume it’s their time to relax about their weight and diet and give into the cravings, excessive weight gain during pregnancy can cause serious health problems.

On the other hand, women who are pregnant are generally receptive to health issues, with many quitting smoking and drinking and being concerned about their diet and health, to do everything possible not only to give their baby the best start in life, but also protect their own health during the pregnancy. It’s said that pregnancy is the only time a person goes to hospital without being ill, but none the less it is a delicate time for a mother to be.

The researchers, led by Dr Shakila Thangaratinam from Queen Mary, University of London, investigated looked at both of diet and exercise, or a combination of both, to assess how that could factor into weight gain during pregnancy. They also wanted to see if dieting and calorie control would have any adverse effects on mother or baby.

The study is quite impressive, with 44 randomized controlled trials being put in place to involving some 7,000 women. The design of the study was taken into account to minimize bias. Diet was clearly the most effective, with a 4kg reduction in weight gain, compared with only 0.7kg for exercise and 1kg for the combination of both. Diet also prevented the most complications with blood pressure, pre-eclampsia, diabetes, and premature birth being reduced, but the overall evidence rating was low to very low.

While the authors conclude that dietary and lifestyle interventions do not adversely affect the baby’s birth weight and can be positive for both mother and baby, they take note of risk factors, such as mother’s age, ethnicity and socioeconomic status. At the same time, accompanying editorial from experts at St Thomas’ Hospital in London, say there is not yet sufficient evidence to support any particular intervention.

Lucilla Poston and Lucy Chappell say they welcome the study, but does not go as far as to provide evidence needed for the National Institute for Health and Clinical Excellence (NICE) to reassess the guidelines for weight management in pregnancy. They point to the future though, and mention several ongoing trials that they hope will enable a better understanding of the best types of interventions for overweight and obese women curing pregnancy.

Written by Rupert Shepherd