Pregnant women warned not to eat for two: Study

By Dr. Ananya Mandal, MDMay 19 2011

According to health experts, there is a “life-long obesity risk of 'eating for two' in pregnancy”. The common advice is reinforced by the results of a study that followed women for a number of years.

The study used the body mass index (BMI) to follow 2,356 UK mothers during their pregnancy and once again 16 years later. Women were divided into groups depending on whether their weight gain during pregnancy was above or below US guidelines, with the researchers looking at how this related to their body shape and chances of being overweight 16 year later.

Overall the study highlights the importance of nutrition in pregnancy. The researchers say there is a “window of opportunity” in pregnancy where paying attention to things like weight gain could improve health outcomes for mothers and children later in life.

The study was carried out by researchers from the University of Bristol and the University of Glasgow. It was supported by grants from several research institutes, including the Wellcome Trust in London, the US National Institutes of Health and the UK Medical Research Council. It was published in the peer-reviewed American Journal of Clinical Nutrition.

Questionnaires were used to collect a range of other data, such as socioeconomic status (based on parental occupation), height, pre-pregnancy weight, smoking during pregnancy, physical activity and diet in pregnancy, duration of breastfeeding and current smoking habits.

Women with low gestational weight gain (GWG) (according to the US Institute of Medicine definition) had on average lower BMI and waist circumference than women who had gained recommended weight levels during pregnancy. Women with a high GWG had a higher average BMI, waist circumference and blood pressure at 16 years.

After making their adjustments the researchers found that there was a three-fold increase in the chance that those with a high GWG were overweight and had central obesity at 16 years compared with those who put on the recommended amount of weight during pregnancy. Pre-pregnancy weight was positively linked to all outcomes; that is, the higher the woman’s pre-pregnancy weight, the greater her BMI, waist circumference and blood pressure 16 years after the pregnancy.

NHS guidelines specifically advise against eating for two. They suggest that in the first six months of pregnancy, a woman’s recommended energy intake of 1,940 calories a day does not change. In the final trimester, pregnant women need around 200 extra calories a day, equivalent to two slices of toast with butter.

Maternal obesity has become one of the biggest risks in childbirth. In 2007 it was found that half of all women who died during pregnancy or soon after giving birth were overweight. The problem is increasing the burden on the NHS. Maternity units have had to order special operating tables, wheelchairs and other equipment to deal with the increasing number of obese mothers and doors have had to be widened to accommodate them. High risk caesarean sections carry increased risk of potential complications including infection, bleeding and clots while babies born to overweight women are at greater risk of diabetes and obesity.

Dr Abigail Fraser, the report’s main author, said, “Our findings suggest that regular monitoring of weight in pregnancy may need to be reconsidered because it provides a window of opportunity to prevent health problems later in life. You don’t need to eat for two in pregnancy because this will cause you problems in later life, and is also linked to a higher risk of your baby becoming obese in childhood.”