Being overweight and obese could up your risk of giving birth to a premature baby, says a new study.
The babies could also suffer from numerous health problems due to preterm birth.
Dr. Sarah McDonald, associate professor in the Michael G. DeGroote School of Medicine's Department of Obstetrics and Gynaecology found that overweight or obese women have a 30 per cent greater risk of induced preterm birth before 37 weeks and that risk climbs to 70 per cent for very obese women.
McDonald said the popular view that a pregnant woman is eating for two is not true.
"It's just not right. Typically, women should add about 300 calories a day - the equivalent of a large glass of milk and a piece of fruit - in the latter half of their pregnancy," she said.
"Family doctors, nurses, obstetricians, public health nurses, and dieticians are all important in delivering a consistent message.
"Women often make many positive lifestyle changes for their pregnancies to have healthier babies, so now we need to make sure that they are aware of these findings so they can optimise their weight before pregnancy."
The research appears in the latest issue of the British Medical Journal (BMJ).