Healthy Living

Pregnancy and Weight: Why It Matters

Jun. 11, 2024
How obesity, weight loss, and weight gain affect pregnancy health.

If you’re pregnant or considering having a baby, you likely have a long list of questions. Weight gain and loss might be on that list—and it should be, according to UR Medicine Obstetrics & Gynecology expert Stacy Sun MD, MPH.

Sun shares ways to be as healthy as possible for your baby, the ranges of healthy weight gain, and what to consider if you’re obese.

How much weight is normal to gain during pregnancy?

Everyone will gain weight during pregnancy, mostly during the 2nd and 3rd trimesters. While the amount will be different for everyone, the recommended ranges are important to know.

    In general, the average ranges of healthy weight gain during pregnancy—based on body mass index (BMI) are:

    • BMI 20-25: 25-35 lbs
    • BMI 25-29: 15-25 lbs
    • BMI > 30: 11-20 lbs

    But, remember the big picture.

    Just like a child’s growth curve, the overall trend of weight gain is key,” says Sun.

    To help keep your baby healthy, health care providers recommend against trying to lose weight or severely restricting weight gain during pregnancy.

    Does being overweight while pregnant lead to more risks?

    Yes. Being overweight or obese is associated with increased risks of both maternal and fetal complications. These risks include:

    • Miscarriage
    • Stillbirth
    • Heart conditions
    • Endometritis (uterine infection)
    • Venous thrombosis (clots)
    • Gestational diabetes
    • Having a baby that’s smaller or larger than average
    • Spine, brain, and heart complications for the baby

    While some of these risks are directly related to physical health, some may also be connected to the limitations of medical technology. Ultrasound and genetic testing are not as accurate for patients who are obese compared with patients of average weight.

    “There’s a huge gap in literature about taking care of our patients who are obese. It’s a community we don’t serve as well,” Sun says. “There are many inequities related to someone’s size, on the community level and the technology level.”

    Salmon, avocado, whole grains, and vegetables lie on a kitchen table

    What can I do to help decrease the risks if I’m overweight?

    Sun recommends weight control before pregnancy if possible. “This doesn’t necessarily mean a huge loss of weight,” she emphasizes. Even small weight reduction, from 5-7%, before pregnancy is associated with drastically improved pregnancy outcomes.

    If you’re overweight, in addition to the standard recommendations, you may want to consider:

    • Early glucose testing
    • Talking to your doctor about taking aspirin to reduce the risk of preeclampsia (high blood pressure during pregnancy)
    • Talking to your doctor about your current medications
    • Early genetic testing

    Can you have a healthy pregnancy if you’re overweight?

    Yes, absolutely. But Sun encourages people who are pregnant to keep a healthy lifestyle, which is the same recommendation for anyone, regardless of weight. This might include:

    • Limiting sugar intake
    • Eating a healthy diet of fiber, fruits, and vegetables
    • Exercising regularly

    • Seeing health care providers
    • Monitoring blood pressure
    • Taking prenatal vitamins

    Looking for more information? UR Medicine offers expert family-planning resources and renowned maternity sites.

    Learn more