Obesity in Pregnancy

How much weight should I gain?

By:  Dr. Dina Deldon-Saltin

It is no secret that in the last 20 -30 years there has been an epidemic of obesity in this country.  Currently 2/3 or 66% of all women in the United States are considered overweight and 1/3 of these women are considered obese.   Obesity is associated with reduced fertility primarily as a result of decreased and lack of ovulation (monthly release of egg from ovary).  During pregnancy, additional risks occur in obese patients including, but not limited to gestational diabetes, preeclampsia, cesarean delivery and infectious morbidity.

Maternal obesity can have effects on the fetus as well, including increased risks of congenital anomalies, growth abnormalities, miscarriage, and stillbirth.  The most common types of obesity-associated birth defects are related to the neural tube, heart and facial clefting.  In addition increased body mass impairs visualization of ultrasound images and can compromise prenatal diagnosis of these fetal anomalies.  Although some studies have reported an increase in small infants, most studies report an increase in large and macrosomic infants.  The risk of stillbirth is 2-4 times greater in obese compared with normal weight women.

Since the beginning of the twentieth century recommendations for weight gain during pregnancy have changed.  These changes have mirrored nutritional status of pregnant women and fetal outcomes.  In the early 1900’s, recommendations were between a 15 and 20 lb weight gain.  Between 1970 and 1990 weight gain recommendations increased to 20-25 lbs.

In August 2009 these recommendations changed once again. This time the change in recommendation for weight gain is dependent on one’s Body Mass Index or (BMI).  A person’s BMI is a standardized calculation of weight based on an individual’s height and can be calculated by dividing one’s weight in kilograms by meters squared.  The following webpage can help you calculate this yourself.


Women with a BMI under 18.5 are considered underweight and should gain approximately 1 lb a week in pregnancy or 28-40 lbs total

Women with a BMI between 18.5 and 24.9 are considered normal weight and should gain approximately 1 lbs a week or 25-35 lbs total.

Women with a BMI between 25 and 29.9 are considered overweight and should gain approximately 0.6 lbs a week or 15-25 lbs total

Women with a BMI greater than 30 are considered obese (class I =BMI 30-34.9, class II= BMI 35-39.9, Class III=  BMI >40).  In all classes of obesity women should gain approximately 0.5 lbs a week or between 11-20 lbs.

For women carrying twins add about another 10 lbs onto weight gain recommendations.