Healthy weight gain in pregnancy and why it's good

AllisonMS, RDN, CDN


  • Why healthy weight gain matters and how much is considered healthy
  • When to increase your food intake (and with what kind of food) and when not to
  • Understand the risks of gaining too much or too little weight and how to stay on a track

The recommendations for weight gain during pregnancy are based on your pre-pregnancy body mass index (BMI). Gaining the recommended amount of weight in pregnancy is associated with optimizing health outcomes for you and your baby – you are more likely to be well-nourished, your baby will be more likely to grow to an appropriate gestational size, and you’ll have an easier time carrying your baby to term and returning to your pre-pregnancy weight.

Calculate your BMI by dividing your pre-pregnancy weight in kilograms by your height in meters, squared (or just use an online BMI calculator). Here are some general weight gain recommendations (note that BMI calculations offer helpful guidelines but are not perfect indicators so always talk with your health care provider about the best weight gain plan for you):

Pre-pregnancy weight categoryBMIRecommended total weight gain for one babyRecommended total weight gain for twins
Underweight< 18.528-40 lbs50-62 lbs
Normal Weight18.5-24.925-35 lbs37-54 lbs
Overweight25-29.915-25 lbs31-50 lbs
Obese>3011-20 lbs25-42 lbs

Source: ACOG. Modified from Institute of Medicine (US). Weight gain during pregnancy: reexamining the guidelines. Washington, DC. National Academies Press; 2009. ©2009 National Academy of Sciences

If you are carrying more than two babies you should talk with your healthcare provider about your expected weight gain.

The recommended pattern of weight gain during pregnancy is about one pound per week during the 2nd and 3rd trimesters. Underweight women should gain slightly more and overweight women should gain slightly less. Keep in mind that these recommendations are based on averages. It’s ok if your weight gain pattern differs from the approximately 1 pound per week in the 2nd and 3rd trimesters. Some women experience slightly more weight gain one month followed by slightly less weight gain the next. What’s important is that you’re not consistently gaining too much or too little weight. Some women even experience weight loss during the first trimester due to morning sickness. If you are losing weight (especially if it’s more than a few pounds) you should address this with your healthcare provider.

Although nutrient needs increase during the first trimester, your body does not yet need additional calories to support your baby (a fetus is still very small!). You can achieve the increased need for nutrients by eating quality foods (think whole foods, minimally processed) and the steady (not yet increased) need for energy by eating no more than you were eating before you got pregnant. Weight maintenance or slight weight gain (about 1-4.5 pounds) in the first trimester is perfectly normal.

Although it may be tempting to “eat for two”, instead try “thinking for two” and upgrade your dietary choices without overdoing your total dietary intake–you do not actually need to eat much more than usual to keep yourself nourished and help your baby grow. During pregnancy your body becomes more efficient, utilizing more of the nutrients in the foods you eat. This means choosing nutrient dense foods is more important now than ever. If you were a healthy weight before you became pregnant, you will need about 340 additional calories per day during your second trimester and about 450 additional calories per day during your third trimester. If you were overweight or obese before you became pregnant you may need as little as 100 additional calories per day.

It may feel like all of your weight gain is in your belly, but the weight you gain during pregnancy is actually distributed to several areas of your body. For a 30 pound weight gain during pregnancy, the average weight distribution is:

Baby7.5 pounds
Placenta1.5 pounds
Fluid4 pounds
Uterus2 pounds
Breast tissue2 pounds
Blood volume2 pounds
Maternal fat, protein and nutrient stores7 pounds
Amniotic fluid2 pounds

Source: “Weight Gain During Your Pregnancy” 12 July 2018 American Pregnancy Association

Avoiding excessive weight gain during pregnancy will help you to:
  • Reduce pregnancy symptoms such as heartburn, leg cramps, backaches and lack of sleep
  • Continue to move around and stay physically active
  • Maintain a healthy pregnancy and positively impact your baby’s future health
  • Decrease the risk of preterm birth
  • Decrease the risk of giving birth to a baby with an increased birth weight
  • Get back to a healthy postpartum weight
Securing adequate weight gain during pregnancy will help you to:
  • Maintain nutrients and overall healthy for you because the baby gets first dibs on your maternal stores of nutrients
  • Decrease the chance of your baby having a low birth weight, malnutrition and nutrient deficiencies
  • Decrease the risk for preterm birth

What to Do

Keep your weight gain on track

Eating regular meals and 2-3 snacks each day will help keep your weight gain on track and cravings at bay. Eat plenty of fiber (in vegetables, fruits, whole grains, nuts and seeds) and protein (from meat, chicken, tofu, nuts, seeds or nut or seed butter) to keep you fuller longer. And don’t forget to stay hydrated! We often mistake thirst for hunger.

As your calorie needs increase, add extra vegetables, fruits, whole grains, and protein-rich foods to your diet. For example, to reach the extra 340 calories you’ll need in the second trimester, try adding to your day a 6 ounce container of low fat yogurt, a medium apple with a tablespoon of nut or seed butter, or 2 scrambled eggs on a piece of whole grain toast with sliced tomato. To reach the extra 450 calories you’ll need in the third trimester, try eating 1 ounce of almonds or pumpkin seeds, a cup of skim or soy milk, sliced raw vegetables with ¼ cup hummus and a small piece of fruit, or a turkey sandwich with 2 ounces of turkey from a roasted turkey breast (it’s advisable to avoid deli turkey slices given the severity of listeria in pregnant women), 1 ounce of cheese or ¼ avocado and two slices of whole grain bread.

If you’re trying to be strict about your weight gain, you can always refer to an online calorie calculator to make sure you’re not eating too much or too little.

Incorporate exercise to keep your weight gain in check

Most pregnant women should aim to get at least 150 minutes of moderate-intensity aerobic activity a week. If that’s more than you’ve been doing, start slowly and work your way up. Not only will exercise help control your weight gain, but it will also help you stay fit and feel less discomfort. Consider swimming, walking, yoga or aerobics classes designed for pregnant women. Talk with your healthcare provider if you have any concerns about your exercise routine.

Don’t weigh yourself often

It’s perfectly fine to wait for your monthly doctors appointments to assess your weight gain unless you are concerned that you’re gaining too much or too little. If you choose to track your weight gain more closely (or if your doctor recommends you do so), weigh yourself at home no more than once a week, ideally at the same time of day and in the same state of dress or undress, and make note of your weight change. Remember that every woman is different and your weight gain pattern may vary slightly from what’s considered typical.

Make adjustments as needed

If you’re not gaining enough weight you may need to eat a little more or decrease your activity level slightly. If you are gaining too much weight you may need to eat a little less or increase your activity level. Stay in tune with your body to find the right balance for you.

Speak to your healthcare provider with any concerns

If you have any concerns about your weight gain you should speak to your healthcare provider. Additionally, reach out to the Happy Mama Mentors who can provide guidance on how to achieve healthy weight gain throughout your pregnancy.

For more on this topic, check out the following articles: