When we think of pregnancy, we may think of the ancient joke, “You’re eating for two now,” or imagine nighttime treks to the kitchen to snack with wild abandon. We’ve seen it depicted on TV and in movies over and over: gaining a lot of weight during pregnancy is expected.

But the conversation surrounding weight gain during pregnancy is a complex one, and one that will differ for every pregnant mom depending on her starting weight. There is such thing as gaining too much weight during pregnancy. And if you are considered medically obese when becoming pregnant, this can create serious medical risks for you and your baby.

Dr. Jennifer Neilsen, an OB-GYN and director of women’s services at Novant Health New Hanover Regional Medical Center, helps moms-to-be cut through the confusing mixed messages when it comes to weight gain during pregnancy. She’s passionate about creating a supportive environment for moms and helping them understand the nuances of what a healthy pregnancy weight means.

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What qualifies as being medically obese?

A person is considered medically obese if he or she is 20% over the ideal body weight. Doctors use a computation called body mass index, or BMI, to calculate this, Neilsen explained. In adults, a BMI of 18.5 to 24.9 is defined as normal, while BMI of 25.0 to 29.9 is categorized as overweight, and BMI greater than 30.0 pertains to the obese category.

Of course, some weight gain during pregnancy is expected, beneficial and completely normal.

Dr. Jennifer Neilsen
Dr. Jennifer Neilsen

“Even if you're obese, you're not advised to lose weight in pregnancy,” Neilsen said. “You're supposed to gain some weight. It takes energy to grow a baby. But you'll want to minimize the weight gain.”

How much weight gain is ideal during pregnancy depends on your starting weight. A mom who is underweight when becoming pregnant should aim to gain 28-40 pounds during pregnancy, while a mom who is obese when becoming pregnant should aim to gain 11-20 pounds. This infographic from the Institute of Medicine details these numbers further.

Obesity during pregnancy is very common, Neilsen said. In the United States in 2020, 31.1% of women ages 18-44 were obese. Obesity, of course, is one of the most common and serious health problems in the U.S. But it presents an extra layer of concerns for women who are expecting.

5 tips for maintaining a healthy pregnancy weight

  1. Aim to consume 70 grams of lean protein each day from sources like eggs, beans, low-fat dairy like Greek yogurt, chicken and beans. Fish is a great protein source, too. Just go for low-mercury fish like salmon, which is also high in beneficial fats.
  2. Try to get 30 minutes of exercise, like walking or swimming, most days. You can split your exercise up into three 10-minute increments and still receive the same benefits. Exercising with a friend or family member can help make it fun and keep you accountable. If you’re starting to exercise for the first time, talk to your doctor before you begin.
  3. If you struggle with being aware of your food choices, try keeping a food log where you write down what you are eating and in what portions. This is a great tool to have when consulting a dietitian or nutritionist. An app like My Fitness Pal can make logging your food easy and quick.
  4. You don’t have to meticulously track your calories, but it’s helpful to know what you’re aiming for. Ask your OB/GYN what the right amount of daily calories is for you. For most pregnant women, the right amount of calories is 1,800 calories a day in the first trimester; 2,200 calories a day in the second trimester; and 2,400 calories a day in the third trimester.
  5. Make sure to drink enough water. The American Congress of Obstetricians and Gynecologists recommends between 8 to 12 cups (64 to 96 ounces) a day. Fruits with high water content – like citrus, apples, berries, plums and pears – can help keep you hydrated and also contain healthy dietary fiber.

What are the health impacts for a mom who is obese during pregnancy?

There are numerous serious health risks to moms who are medically obese during pregnancy. These include:

  • Gestational diabetes.
  • Preeclampsia, a complication caused by high blood pressure during pregnancy.
  • Blood clotting problems, including venous thromboembolism (VTE), when a blood clot breaks off and travels through the blood to organs like the brain, lungs or heart. This can lead to heart attack or stroke.
  • Sleep apnea.
  • Labor complications, such as the need for cesarean section, problems with anesthesia, longer labor, and/or the need to have your labor induced.
  • Miscarriage or stillbirth.

Black women may be particularly at risk for weight-related pregnancy complications, since four out of five Black women in the U.S. are overweight or obese, the U.S. Department of Health and Human Services Office of Minority Health reports. Because of several underlying factors, Black women also face disproportionately higher rates of maternal mortality, a systemic problem that Novant Health is working to address.

Does obesity during pregnancy affect baby’s health?

There are potential risks for your baby. These include:

  • Premature birth.
  • Birth defects, including neural tube (brain and spine) defects and heart defects.
  • Macrosomia, or high birth weight, which can cause complications during labor and birth, including injury.
  • Gestational diabetes may cause health problems for your baby including breathing complications, low glucose levels and jaundice.

Neilsen also points out that obesity during pregnancy may “perpetuate further complications down the road” for children. “There's a higher instance of abnormal glucose levels in these babies,” she said. “They have more body fat and sometimes the bigger body fat distribution means they’re more prone metabolically to childhood obesity.”

Childhood obesity is associated with a higher chance of premature death and disability during adulthood, the World Health Organization reports.

What steps can a pregnant mom take to maintain a healthy body weight before and during pregnancy?

Small changes are important and do add up, Neilsen said. Women often shoulder a lot of responsibility when making healthy choices for themselves and their families, so it’s important not to feel guilty or ashamed.

Neilsen recommends starting with small amount of light to moderate exercise for 150 minutes a week.

“That would be if you did a half-hour a day, most days of the week. Go out for a little walk,” she said.

This moderate level of exercise has numerous benefits in addition to helping with weight management, including building strength and stamina for labor and aiding in recovery after delivery.

Neilsen also suggests keeping in mind that all foods and beverages you consume will be fuel for your baby. This makes it important to eat a variety of wholesome foods like fruits, vegetables and lean protein. She encourages people to think of food as balance and energy, not companionship and comfort.

“Think about what building blocks you want to make your little person,” she said. “If you wouldn't give your baby sweet tea, don't drink sweet tea.”

If you’re not sure where to start, connecting with a support system is great step in the right direction. If you’re in the “thinking about it” phase of pregnancy, a preconception visit with an OB-GYN is a smart way to ensure you’re prepared for a healthy pregnancy. Being a healthy weight before becoming pregnant is a great way to decrease pregnancy risks. As a bonus, being a healthy weight can also help improve fertility.

During pregnancy, Novant Health nutrition counselors can assist moms with making healthy choices.

“Nutritional counseling can help you utilize what you have available and make you aware of what you're putting into your body as building blocks for our next generation,” Neilsen said.