Weight Gain During Pregnancy

By OBGYN Dr. Kenosha Gleaton

Weight gain during pregnancy has the ability to impact maternal and infant health. Studies show that being overweight or underweight during pregnancy is associated with changes in gestational weight, developmental outcomes, and more. [1] This is why eating a balanced diet and the appropriate amount of calories during pregnancy is so important. Let’s talk a bit more about managing weight during pregnancy. 

What Causes Weight Gain During Pregnancy?

It is expected and healthy for pregnant people to gain some weight during pregnancy, especially during the second and third trimester. The majority of this weight gain is directly associated with your growing baby and the body tissue needed to support your pregnancy. [2] According to the National Library of Medicine, weight gain during pregnancy can be broken down as follows [2]:

• Baby: 8 lbs
• Placenta: 2-3 lbs
• Amniotic fluid: 2-3 lbs
• Uterus growth:  2-5 lbs
• Fat stores: 5-9 lbs
• Breast tissue: 2-3 lbs
• Blood supply: 4 lbs

How Much Weight Should You Gain During Pregnancy?

To promote positive health outcomes for yourself and your child, it’s important to gain a healthy amount of weight during pregnancy. The amount of weight you should gain will depend on your prepregnancy weight and may also be impacted by factors such as multiple pregnancy, underlying health conditions, etc. [3] The Institute of Medicine (IOM) has put together a chart of weight recommendations for pregnancy that shows the following [1,3]:

There have been some criticisms of this chart, with some healthcare providers believing weight targets are too high, especially for those overweight or obese. [3] It’s important to speak directly to your healthcare provider about your weight gain during pregnancy to determine what is healthy for you.

When Do You Gain The Most Weight During Pregnancy?

Most pregnant people will gain anywhere between 25 to 35 lbs during pregnancy, and the majority of this weight will be gained during the final two trimesters. [1-3] It’s common to notice slight weight gain, about 2-4 lbs, during the first trimester, then many will begin to gain about one pound a week for the rest of the pregnancy. [2-3] 

Being Underweight During Pregnancy

Being underweight or gaining less than the recommended amount of weight during pregnancy can be dangerous. Being underweight may result in delivering a low birth weight baby and can increase the risk of illness, developmental delays, and difficulty breastfeeding. [1] 

Gaining Weight While Pregnant

If you aren’t seeing the number on your scale go up, speak to your healthcare provider before taking any action. They may not be concerned about weight gain if you are a healthy weight or if you’re early on in your pregnancy. [3] Pregnancy weight should begin to rise on its own as your body continues to grow and change to support your baby. 

It is important to make sure you’re eating enough. On average, anyone that is pregnant should be consuming an additional 340 calories a day during the second trimester, and an additional 450 calories a day during the third trimester. [3] If you’re carrying twins or triplets, this number is even higher. 

Effects of Being Overweight During Pregnancy

Gaining excess weight or being overweight during pregnancy can also be dangerous. Being overweight is associated with having a baby that is born too large, potentially leading to delivery complications, cesarean delivery, and childhood obesity. [1] Excess weight during pregnancy is also associated with high blood pressure, preeclampsia, preterm birth, and gestational diabetes. [4] 

Losing Weight While Pregnant

Losing weight should not be a goal of yours during pregnancy unless a healthcare provider has recommended it. If you do need to lose weight or keep a close eye on any weight gain, you and your healthcare provider will come up with a diet and exercise plan together. Remember that gaining weight is a normal and healthy part of pregnancy! 

Maintaining a Healthy Weight During Pregnancy

Everyone’s pregnancy journey will look different, and weight management can also vary greatly from person to person. Depending on your prepregnancy weight and any ongoing conditions or complications, you and your healthcare provider can determine what healthy weight management will look like for you. [3,4] Similarly to weight management outside of pregnancy, you need a healthy balance of diet and exercise. 

Diet During Pregnancy

In order to get all the nutrients you need while adequately fueling your body, you should be making healthy choices for food and drink and consuming the recommended amount of additional calories per day. Some healthy food choices include [2,4]:

• Fresh fruits and vegetables
• Whole grain products
• Lean protein
• Low-fat and fat-free dairy products

Foods to avoid include highly processed, fatty, or fried foods. 

It’s also important to drink plenty of water during pregnancy. ACOG recommends drinking between 8 to 12 cups of water every day. [4] 

Exercise During Pregnancy

Exercising during pregnancy can be a great way to promote overall health, but should not be done to lose weight unless instructed by a healthcare provider. Exercise may be able to ease back pain, constipation, strengthen the heart, and decrease the risk of gestational diabetes and preeclampsia. [5] Ideally you can aim for at least 150 minutes of moderate-intensity aerobic activity every week. Some examples include gardening, walking, dancing, and water aerobics. As a gesture of care, you might consider treating an expectant mother to a thoughtful pregnancy gift basket to complement her wellness journey. Exercise may not be right for everyone, so it's advisable to speak to your healthcare provider before attempting any new exercises. 

Key Takeaways

Keep in mind that these recommendations are based on average population data, and it’s important that you speak to a healthcare provider directly to determine what healthy weight management looks like for you. There are many factors to take into consideration, including medical conditions, prepregnancy weight, previous pregnancies, age, and more. [1-4] Two steps all pregnant people should take are finding a comprehensive prenatal multivitamin and staying hydrated with water or electrolyte drinks. [4] 

References:

1. Weight Gain During Pregnancy. Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion. CDC. June 2022. URL. 
2. Managing your weight gain during pregnancy. Medline Plus. NIH. November 2022. URL. 
3. Weight gain during pregnancy. Committee Opinion No. 548. American College of Obstetricians and Gynecologists. Obstet Gynecol 2013;121:210–2.
4. Nutrition During Pregnancy. FAQ 001. American College of Obstetricians and Gynecologists. June 2023. URL. 
5. Exercise During Pregnancy. FAQ 119. American College of Obstetricians and Gynecologists. March 2022. URL.