How Much Weight Should You Gain During Pregnancy?

At every prenatal checkup, you step on the scale, and a nurse records your weight. But why is weight gain so crucial when you’re expecting? And realistically, how much weight should you gain during pregnancy?

Here’s a look at weight gain during pregnancy: How much is too much (or too little), and why it matters.

Weight Gain During Pregnancy

Gaining the right amount of weight when you’re pregnant is vital for your health — and the health of your baby. For most women, the optimal weight gain during pregnancy is between 25 and 35 pounds.

However, suggested average weight gain during pregnancy can vary. Your weight gain depends on your weight and height prior to pregnancy. Women carrying twins will gain more weight than those with a single pregnancy.

The Centers for Disease Control and Prevention (CDC) recommends basing pregnancy weight gain on your body mass index (BMI).

If, before pregnancy, you were:

  • Underweight (BMI less than 18.5), you should gain 28 to 40 pounds.
  • Normal weight (BMI 18.5 to 24.9), you should gain 25 to 35 pounds.
  • Overweight (BMI 25 to 29.9), you should gain 15 to 25 pounds.
  • Obese (BMI 30 or more), you should gain 11 to 20 pounds.

Here’s how the ideal 25 to 35 pounds breaks down:

  • Amniotic fluid: 2 to 3 pounds.
  • Baby: 7 to 8 pounds.
  • Breast tissue: 1 to 3 pounds.
  • Fat stores: 5 to 9 pounds.
  • Growth of uterus: 2 to 5 pounds.
  • Increase in blood supply: 3 to 4 pounds.
  • Placenta: 2 to 3 pounds.

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Problems with Gaining Too Much Weight

If you gain too much weight during pregnancy, you’re also at risk of having:

  • A baby that’s too big. The term “fetal macrosomia” describes any newborn who weighs more than 8 pounds, 13 ounces. A large baby can cause complications like tearing and heavy bleeding during labor.
  • A C-section. Doctors cut into your belly and uterus to deliver the baby. This is a major surgery that comes with greater risks and a longer recovery time than a vaginal birth.
  • Gestational diabetes. You may develop this form of pregnancy-related diabetes, which increases your chances of having a baby that’s too big.
  • Preeclampsia. This pregnancy-related rise in blood pressure can become serious if not detected and closely monitored.
  • More postpartum weight to lose. Becoming overweight increases your risk of many chronic health problems, including high blood pressure, heart disease, and diabetes.

Problems with Gaining Too Little Weight

Not gaining enough weight is another potential problem. Your body may not store enough resources to nourish the baby. Gaining too little weight may put your baby at risk for:

  • Low birth weight. If your baby weighs less than 5 pounds 8 ounces, they are at risk for illness and developmental delays. Low birth weight babies may also have trouble breastfeeding.
  • Prematurity. If your baby is born early, they may have to stay in the newborn intensive care unit (NICU) for days or weeks. Premature babies are at risk for long-term health problems as well as intellectual and developmental disabilities.

When You Should Gain Pregnancy Weight

During your first trimester (the first 12 weeks of pregnancy), you may only gain a few pounds. Some women don’t gain any weight during these months, especially if they have morning sickness. You don’t need to consume any extra calories during the first trimester.

A slow, steady weight gain during the second and third trimesters is best. If you were a healthy weight before pregnancy, gaining half a pound to a pound a week is best.

During the second trimester, you should eat an extra 340 calories per day. In the third trimester, you should eat about 450 extra calories per day. These extra calories should come from high-nutrition foods, not burgers and milkshakes.

Achieving a Healthy Weight Gain During Pregnanc

What if you were overweight or underweight when you got pregnant? Now is not the time for a crash diet — or a junk food binge. But it’s a great time to tweak your lifestyle habits to support a healthy pregnancy.

Of course, consult your ob-gyn when making any lifestyle changes during pregnancy. Here are some strategies your doctor may suggest:

Adopt healthy eating habits

It’s never too late to eat healthier, and it’s never more important than when you’re pregnant. To have a healthier pregnancy:

  • Choose fats and oils from plant sources such as olive oil, nuts, and avocados. Limit any fats that come from animals.
  • Don’t smoke or drink alcohol.
  • Fill your plate with whole grains, lean protein, and lots of fruit and vegetables.
  • Limit foods that contain empty calories. That includes cookies, cakes, candy, fast food, sodas, and fried or processed foods.
  • Talk to your doctor about foods you should and shouldn’t eat. For instance, some fish are off-limits for pregnant women because they may contain mercury. Your ob-gyn may also tell you to take a prenatal vitamin.

Drink lots of water

Trade sugary drinks, caffeine, and alcohol for water during pregnancy. Your body needs 8 to 12 cups (64 to 96 ounces) of water daily when you’re expecting.

Water helps your digestion, allows nutrients to circulate through the body, and aids in waste leaving your body. It also helps the amniotic fluid to form around your baby.

You should drink water throughout the day, not just when you’re thirsty.

Get (or stay) active

With your doctor’s OK, you can exercise when you’re pregnant. Keeping your body strong will help you maintain a healthy weight and boost your stamina during labor and delivery. You’ll also bounce back from pregnancy more quickly.

Aim for 150 minutes of activity each week. You can break this up into 30 or even 10 minutes at a time.

Brisk walking is a great way to stay fit during pregnancy. In the winter, indoor swimming is a good option.

Get regular prenatal checkups

Seeing your ob-gyn regularly during your pregnancy is essential. Your doctor can advise you on a healthy pregnancy, including weight gain. Regular checkups will also help catch any problems (like gestational diabetes or preeclampsia) early so you can get treatment.

Editor's Note: This article was originally published on , and was last reviewed on .

Centers for Disease Control and Prevention. Weight Gain During Pregnancy. LINK

National Library of Medicine. MedlinePlus. Managing Your Weight Gain During Pregnancy. LINK

National Institutes of Health. National Library of Medicine. Pregnancy and Birth: Weight Gain in Pregnancy. LINK

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