Many studies have suggested that too much, or too little, weight gain in pregnancy can be harmful to both baby and mother.  A recent review brings together data from over 1.3 million women, to help us understands what the health risk are of inappropriate weight gain in pregnancy.

First, let’s review the recommendations for weight gain in pregnancy.  The recommended amount is based on Body Mass Index pre pregnancy, which is calculated by your weight in kg, divided by your height in metres squared (kg/m2). Note that these numbers apply to single pregnancies only (recommendations are higher for twin, triplets etc).


  • BMI less than18.5:  28-40 lbs (about 13-18 kg)
  • BMI 18.5-24.9:       25-35 lbs (about 11-16 kg)
  • BMI 25-29.9:          15-25 lbs (about 7-11 kg)
  • BMI 30 or more:     11-20 lbs (about 5-9 kg)

The review, published in the Journal of the American Medical Association, found that gestational weight gain fell below these guidelines in 23% of pregnancies, and above these guidelines in 47% of the pregnancies studied.

For women not gaining enough weight in pregnancy, there was a 53% higher risk of having a small for gestational age baby, and a 70% increase in the risk of preterm birth.

For women gaining excessive weight in pregnancy, there was an 85% higher risk of having a large for gestational age baby, and a 30% increased risk of needing a C section.

Not only do we know that it is important to manage weight during pregnancy, but optimizing weight prior to pregnancy is important too, as underweight or overweight pre-pregnancy is also associated with adverse outcomes.

If you are pregnant or thinking about becoming pregnant, be sure to speak with your doctor about optimizing weight both before and during pregnancy.


Follow me on twitter! @drsuepedersen © 2017