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Healthy weight gain: The BMI breakdown for your pregnancy

Weight gain and pregnancy go hand in hand, but how much is too much weight to gain? Or conversely, how much is too little? 

You don't want to try to lose weight during your pregnancy. But you do want to keep an eye on how much weight you gain—for the sake of your health and the health of your baby.

Why weight gain is important

If you put on too little weight during pregnancy, you're at an increased risk for having a premature baby or a baby with a low birth weight. Premature babies may be born with health problems and are more likely to have health problems later in life, such as being overweight or obese.

If you put on too much weight during pregnancy, you are at an increased risk for:

  • Having a premature baby. 
  • Having a baby with fetal macrosomia, which means your baby is born weighing more than 8 pounds, 13 ounces. Delivering a baby this large can lead to complications, such as problems during labor and heavy bleeding after birth.
  • Needing a cesarean birth.
  • Having trouble losing weight after childbirth. This can increase your risk for health problems like diabetes and high blood pressure.

How much weight should you gain?

Recommendations for how much weight you should gain during pregnancy depend on how much you weighed prior to getting pregnant. 

One way your doctor may measure the health of your pregnancy is to track your weight gain through your body mass index (BMI). BMI is a measure of body fat based on calculations of your weight and height. You can figure out your BMI by using our simple BMI calculator

Here's how pre-pregnancy BMI breaks down:

  • Underweight—your BMI is less than 18.5.
  • Healthy weight—your BMI is between 18.5 and 24.9.
  • Overweight—your BMI is between 25 and 29.9.
  • Obese—your BMI is 30 or higher.

Based on your pre-pregnancy BMI, here's how much weight you should gain according to both the March of Dimes and American College of Obstetricians and Gynecologists:

  • If you were underweight, you want to gain about 28 to 40 pounds during pregnancy.
  • If you were at a healthy weight, you want to gain about 25 to 35 pounds during pregnancy.
  • If you were overweight, you want to gain about 15 to 25 pounds during pregnancy.
  • If you were obese, you want to gain about 11 to 20 pounds during pregnancy. 

It's normal to have questions and concerns about weight gain during pregnancy. Just remember that your doctor is the best judge of a healthy weight gain. He or she will check your weight at each prenatal visit to monitor your added weight, but you can always reach out between appointments with any questions. 

Your first trimester tests

Have you been wondering why kinds of tests you and your growing baby will be getting? Check out what's in store for your first trimester tests.  

Sources: American College of Obstetricians and Gynecologists; March of Dimes

Reviewed 12/18/2023

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