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Weight Gain During Pregnancy: Answers to Common Questions

By Marisa Cohen
Reviewed by Alyssa Quimby, M.D.
May 05, 2023

Getting weighed regularly is a part of being pregnant: It’s one way that doctors track the progress of you and your baby. You can expect to step on the scale at every prenatal visit. Those appointments happen about once every four weeks for the first two trimesters, then every two weeks until 36 weeks, and finally every week until you give birth.

Weight gain during pregnancy isn’t just due to the baby growing inside you, says Tara Scott, M.D., medical director at Forum Health, in Akron, Ohio. There’s also an increase in blood volume, she says—as much as 40% by your third trimester. On top of that, Scott says, in preparation for feeding your baby, your body will store fat, and your metabolism will slow down to conserve energy.

How Much Weight Gain Should You Gain During Pregnancy?

During the first trimester, you may gain only 1 to 5 pounds, or no weight at all. After that, doctors recommend that you gain about 1/2 to 1 pound per week. The American College of Obstetricians and Gynecologists (ACOG) has guidelines for pregnancy weight gain based on your body mass index (BMI) before you were pregnant (calculate your BMI here). (Note: If you’re pregnant with twins or multiples, those numbers will be higher—if you want to know what your recommendation is, talk to your doctor.)

In many cases, doctors take your pre-pregnancy weight to calculate your recommended weight gain. This might look like:

  • Underweight (BMI < 18.5): Your recommended weight gain is 28–40 pounds.
  • Normal weight (BMI 18.5–24.9): Your recommended weight gain is 25–35 pounds.
  • Overweight (BMI 25–29.9): Your recommended weight gain is 15–25 pounds.
  • Obese (BMI > 30): Your recommended weight gain is 11–20 pounds.

And remember, these guidelines are simply a recommendation and don’t take into account the vast amount of diversity and deviation experienced by all people who are pregnant. “This is just a rule of thumb—some [pregnant people] will gain more, some will gain less,” says Alex Robles, M.D., a board-certified ob-gyn at Columbia University Irving Medical Center, in New York City.

What If I Don’t Gain As Much Weight As Recommended?

Although it’s common for pregnant people to worry about not gaining enough weight, that’s rarely a problem. The first few months of pregnancy can be a time of morning sickness and food aversions, so don’t fret if you can’t seem to stomach anything other than a few saltines, Robles says. “The baby will take what it needs from your body to support its growth and development,” he explains. “Just be sure to stay hydrated, even if you can’t keep down a lot of food.”

There is a condition to watch out for, however: As anyone who was following the three royal pregnancies of the Duchess of Cambridge may remember, she developed a condition called hyperemesis gravidarum, which can cause severe nausea and vomiting during pregnancy, possibly leading to dehydration. If you’re not keeping down fluids, tell your doctor. The condition is highly treatable with IV fluids and anti-nausea medications.

By the second trimester, your doctor will begin to measure your fundal height, which refers to the size of your uterus and is an indicator of the baby’s growth. “As long as the baby is growing,” Scott says, “I wouldn’t be too concerned about not hitting the exact marks for weight gain.”

What If I Gain More Weight Than Recommended?

Although there’s no perfect number for each pregnancy, and stepping on the scale makes some people feel uncomfortable, there are a few things your doctor is keeping an eye on to make sure you and your baby are staying healthy.

One concern with a higher-than-average pregnancy weight gain is what it may say about the size of the baby. Excessive weight gain can lead to a very large baby, Scott says, which can lead to delivery complications. In addition, research suggests that the more weight a pregnant person gains, the higher the risk of developing gestational diabetes.

The best ways to achieve healthy weight gain during pregnancy are the same basic strategies that are recommended at any time in a person’s life: Eat a balanced diet including whole grains, fruits and vegetables, and lean proteins and try to remain active. If you’re hungrier than usual, try to make healthy choices, focusing on getting protein with your snacks, which will fill you up for longer. Examples are apples with peanut butter, carrots and hummus, string cheese, or a handful of almonds.

Also, be aware that your body might not need as many extra calories as you’ve heard. “There’s a common phrase thrown around—“you’re eating for two”—but in reality, you only need to add about 300 to 500 calories a day to support a growing fetus,” Robles says.

When Will I Lose the Pregnancy Weight?

Give it time. It may be at least several months before you return to your pre-pregnancy weight, Robles says. “The only thing that came out of you when you delivered was the baby, the placenta, and the amniotic fluid, and that weighs about 10 pounds total,” he says.

After you give birth, your body will still have extra blood circulating, plus the extra fat stores added during pregnancy, and your breasts will grow heavier with milk. Your uterus doesn’t shrink back down to its normal size until about six weeks postpartum.

You can expect to lose much of the pregnancy wait after 12 weeks—this is one of the reasons those first months after giving birth are sometimes known as the fourth trimester. But expect it all to vary. Your body, like your baby, is on its own schedule.

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