This sheet is about obesity in pregnancy or while breastfeeding. This information is based on published research studies. It should not take the place of medical care and advice from your healthcare provider.
What is obesity?
Obesity is when someone has excess body fat. One measure of obesity is body-mass index (BMI), which is an estimate of body fat based on height and weight. BMI is calculated using weight (kg) and height (m) or pounds (lbs.) and inches, with the formula being weight (kg) / height (m)².
A person is considered to be obese when their BMI is 30 or higher and overweight when their BMI is between 25 and 29.9. The Centers for Disease Control and Prevention (CDC) has a tool to find your BMI: https://www.cdc.gov/bmi/adult-calculator/?CDC_AAref_Val=https://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/english_bmi_calculator/bmi_calculator.html.
What about weight gain during pregnancy?
Weight gain during pregnancy is expected. The suggested amount of weight gain during pregnancy can be different based on your weight/BMI before pregnancy and the number of fetuses that you are carrying. In general, a total weight gain of 15–25 pounds for women who are overweight and 11–20 pounds for women who are obese is recommended during pregnancy. However, it is important to work closely with your healthcare providers to determine how much weight you should gain during pregnancy.
Should I try to lose weight while pregnant?
Weight loss is usually not recommended during pregnancy. Talk with your healthcare provider before trying to lose weight during pregnancy. They can go over your recommended weight gain, nutrition, and exercise.
Can obesity make it harder to get pregnant?
Studies have shown that it can take longer for women who are obese to get pregnant. Also, they may have a lower chance of getting pregnant.
Can obesity increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Obesity has been associated with an increased chance of miscarriage. As there can be many causes of miscarriage, it is hard to know if obesity or other factors (age, health, other exposures) are the cause of a miscarriage.
Can obesity increase the chance of birth defects?
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if an exposure, like obesity, might increase the chance of birth defects in a pregnancy. Obesity during pregnancy has been associated with a higher chance for certain birth defects, including heart defects or defects of the brain, spine, or spinal cord (neural tube defects [NTDs]). While the overall increased chance for birth defects is expected to be small, risks may be higher depending on a person’s level of obesity.
Can obesity increase the chance of other pregnancy-related problems?
Obesity during pregnancy can increase the chance of gestational diabetes, high blood pressure, preeclampsia (high blood pressure that can affect organs such as the kidneys), preterm delivery (birth before 37 weeks of pregnancy), stillbirth, heavy bleeding after delivery (postpartum hemorrhage), and needing a C-section delivery. It can also increase the chance of having a baby with macrosomia (weighing more than 8 pounds, 13 ounces [4000 grams] at birth), which may lead to delivery complications and may increase the child’s risk for low blood sugar, obesity, and heart problems. For more information on gestational diabetes, see the MotherToBaby fact sheet https://mothertobaby.org/fact-sheets/diabetes-pregnancy/.
Can obesity in pregnancy affect future behavior or learning for the child?
Some studies suggest that children born to women with obesity may have a higher chance of learning difficulties, attention-deficit/hyperactivity disorder (ADHD), or autism. However, many factors can influence a child’s behavior and development, and it is unlikely that obesity alone explains these outcomes.
What screenings or tests are available to see if my pregnancy has birth defects or other issues?
Prenatal ultrasounds can be used to screen for some birth defects, such as heart defects and NTDs. Ultrasound can also be used to monitor the growth of the pregnancy. However, obesity can make it harder for birth defects to be detected by ultrasound. Talk with your healthcare provider about any prenatal screenings or testing that are available to you. There are no tests available during pregnancy that can tell how much effect there could be on future behavior or learning.
Breastfeeding and obesity:
Women with obesity can successfully breastfeed and provide all the benefits of breast milk to their baby. Some studies suggest that women with obesity may be less likely to start or continue breastfeeding, but support and resources can help. If you have questions or need assistance with breastfeeding, talk with your healthcare provider, your baby’s pediatrician, or a lactation consultant. They can help you find the support you need to meet your breastfeeding goals. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a man has obesity, can it affect his fertility or increase the chance of birth defects?
Obesity in men can affect fertility (ability to make healthy sperm). Studies have not been done to see if obesity in men could increase the chance of birth defects. In general, exposures that fathers or sperm donors have are unlikely to increase the risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
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