In 2009 a panel of specialists was assembled to review the weight gain recommendations for pregnant women. Guidelines were developed based on whether the women were underweight, normal weight, overweight or obese before becoming pregnant. 

Obesity is becoming a significant health problem for women of child bearing age. Data from the Pregnancy Nutrition Surveillance System at the Center of Disease Control shows that the number of women entering pregnancy overweight or obese increased about 20% over the last 20 years. In 1989, only one third (36%) of women were overweight or obese when they became pregnant and the most recent statistics from 2009 says the number is now up to 53%.

Women who are overweight or obese at the time of becoming pregnant are at a greater risk of gaining more weight. In 2009, about 39% of normal weight women gained weight in pregnancy ABOVE the recent guidelines. For overweight women in the same report, the number was more than half. 59% of overweight women and 56% of obese women gained more weight than recommended.

The weight gain guidelines were developed because of the increased risk that not enough or too much weight gained during pregnancy has on the health of the mother and her unborn baby.

Gaining above the recommendations can contribute to gestational diabetes, high blood pressure, or babies being born either small or large. Mothers gaining excess pregnancy weight are more likely to never lose the weight, and the children have an increased risk of becoming obese themselves.