03/06/2009 10:40 BST | Updated 22/05/2015 10:12 BST

New Guidelines On Weight Gain During Pregnancy

Over in the US, the Institute of Medicine (IOM) has just released new guidelines about how much weight women should put on during pregnancy, largely in response to the US rise in obesity.

The guidelines, the first to be issued by the IOM since 1990, do provide a basis for UK recommendations too.

This latest report from the IOM sets out that women should keep weight gain within limits based on their body mass index (BMI) before pregnancy, rather than stick to a "one size fits all" approach.

The IOM's weight gain guidelines for a woman carrying one child state: If she's underweight, she should gain 28-40 pounds. If she's at a normal weight, she should gain 25-35 pounds. If she's overweight, she should gain 15-25 pounds. And if she's obese, she should gain 11-20 pounds.

Apparently, a normal-weight woman would need only the equivalent of one extra Snickers bar a day to maintain a healthy pregnancy, or in other words 300 extra calories. And yes, you're supposed to make healthier choices than chocolate.They also set out weight guidelines for women before they get pregnant, in a bid to maximise the health of mother and baby from conception onwards.

Meanwhile, US doctor Yvonne S. Thornton, MD, MPH, a clinical professor of obstetrics and gynaecology and board-certified specialist in maternal-fetal medicine at New York Medical College, has conducted research into the effect of a controlled diet on obese women during pregnancy.

Researchers followed 232 pregnant obese women. Half of the group were given a well-balanced nutritionally managed diet, while the other half followed the conventional dietary approach of "eat to appetite".

The study showed that the "eat to appetite" group gained 31 pounds and the nutritionally managed group 11 pounds. However, there were no foetal deaths in the latter group, fewer risky 10 pounds-plus babies, fewer caesarean deliveries and the women retained less weight after they delivered and were less likely to develop gestational diabetes.