BAKERSFIELD, Calif. -- Weight gain during pregnancy varies considerably -- some women gain just 15 pounds while others pack on more than 60.

But what weight target is ideal? According to new guidelines released today by the Institute of Medicine, it depends on a woman's starting point.

Women who have a normal weight at conception should gain between 25 and 35 pounds throughout pregnancy, while underweight women are advised to gain a bit more -- as much as 40 pounds.

But doctors are concerned that many women are now overweight or obese at the start of their pregnancies. Adding even more extra pounds raises the risk for pregnancy complications such as gestational diabetes, premature birth, and Caesarian delivery.

To reduce these risks, the Institute of Medicine recommended that overweight women gain no more than 15 pounds during pregnancy. For obese women, the weight guidelines are even stricter -- just 11 to 20 pounds.

Experts recommended that doctors work closely with obese pregnant women to ensure they are eating healthy meals and not empty calories from soda and junk food.