FAQ Pregnancy
FAQ182, June 2013

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Obesity and Pregnancy

What is the body mass index?

The body mass index (BMI) is a number calculated from height and weight that is used to determine whether a person is underweight, normal weight, overweight, or obese. You can find out your BMI by using an online BMI calculator on a website such as www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm.

When is a person considered overweight?

A person is overweight if he or she has a BMI of 25–29.9.

When is a person considered obese?

Obesity is defined as having a BMI of 30 or higher.

What are the increased risks during pregnancy for my baby if I am obese?

Being obese during pregnancy increases the risk of the following problems for your baby:

  • Birth defects—Babies born to obese mothers have an increased risk of having birth defects, such as heart defects and neural tube defects.
  • Problems with tests—If you have too much body fat, it can make it more difficult to see certain problems with the baby’s anatomy on an ultrasound exam.
  • Macrosomia—In this condition, the baby is larger than normal. This can increase the risk of the baby being injured during birth. Macrosomia also increases the risk of cesarean delivery.
  • Preterm birth—Problems associated with a mother’s obesity may mean that the baby will need to be delivered early. Preterm infants have an increased risk of health problems, including breathing problems, eating problems, and developmental and learning difficulties later in life.
  • Stillbirth—The risk of stillbirth increases the higher the mother’s BMI.

What are the increased risks for me during pregnancy if I am obese?

Obesity during pregnancy puts you at risk of serious health problems:

  • High blood pressure—High blood pressure that starts during the second half of pregnancy is called gestational hypertension. It can lead to serious complications.
  • Preeclampsia—Preeclampsia is a serious illness for both a woman and her baby. The kidneys and liver may fail. In rare cases, stroke can occur. In severe cases, the woman, baby, or both may die.
  • Gestational diabetes—High blood glucose (sugar) levels during pregnancy increase the risk of having a very large baby and a cesarean delivery. Women who have had gestational diabetes have a higher risk of having diabetes in the future, as do their children.

Can I still have a safe pregnancy if I am obese?

Despite the risks, you can have a safe pregnancy and a healthy baby if you are obese. You will need to work with your health care provider to monitor your weight, exercise regularly, get regular prenatal care, and take steps to be as healthy as you can during your pregnancy.

How much weight should I gain during pregnancy?

Weight Before Pregnancy BMI Total Weight Gain Range (pounds)
Normal Weight 18.5–24.9 25–35
Overweight 25–29.9 15–25
Obese 30 or greater 11–20
Modified from Institute of Medicine (US). Weight gain during pregnancy: reexamining the guidelines. Washington, DC. National Academies Press; 2009. ©2009 National Academy of Sciences.

You will discuss how much weight you should gain with your health care provider at your first prenatal visit. The following weight guidelines show the weight gain ranges that are associated with the best possible outcomes for both pregnant women and their babies.

Should I try to lose weight during pregnancy?

Even for obese women, pregnancy is not the time to actively try to lose weight. However, if you are obese and are gaining less than what the guidelines suggest, and if your baby is growing well, gaining less than the recommended guidelines can have benefits, such as decreased risks of needing a cesarean delivery and of having a very large baby.

Will I be tested for gestational diabetes during pregnancy?

Because overweight and obese women have a higher risk of this complication than women who are a normal weight, your health care provider may test you for gestational diabetes during the first 3 months of your pregnancy. You also may be given the test again in the later months of your pregnancy.

If I have never exercised, how should I begin during pregnancy?

Begin with as little as 5 minutes of exercise a day and add 5 minutes each week. Your goal is to stay active for 30 minutes each day. Walking is a good choice if you are new to exercise. Brisk walking gives a total body workout and is easy on the joints. Swimming is another good exercise for pregnant women.

Can I have a vaginal delivery if I am obese?

Vaginal delivery is the ideal way to have your baby. However, a vaginal delivery is not always possible, and being obese can make a vaginal delivery even less likely. It can be harder to monitor the baby during labor. If the baby is very large, difficulties during labor and delivery may arise. For these reasons, obesity during pregnancy increases the risk of having a cesarean delivery.

Is cesarean delivery riskier for obese women?

Cesarean delivery is riskier for obese women than for women of normal weight. In general, the time it takes to perform the operation may be longer. The longer the operation takes, the greater the risks of bleeding and other complications.

Additional risks of cesarean delivery include the following:

  • Infections
  • Problems with anesthesia
  • Deep vein thrombosis (DVT)
  • Poor wound healing

What do I need to do after pregnancy if I had gestational diabetes during pregnancy?

If you had gestational diabetes during your pregnancy, you will need to have a follow-up test of your glucose level between 6 weeks and 12 weeks after you give birth. If your test result is normal, you should be retested for diabetes every 3 years.

Why is it important to lose excess weight before getting pregnant again?

Losing weight before getting pregnant again can help you prevent many of the complications caused by obesity during pregnancy. It is especially important to lose weight before getting pregnant again if you had complications in your previous pregnancy.

How can I lose weight safely after pregnancy?

Once you are home with your new baby, continue your healthy eating and exercise habits. Not only is breastfeeding the best way to feed your baby, it also may help with postpartum weight loss. Overall, women who breastfeed their babies for at least a few months tend to lose pregnancy weight more quickly than women who do not breastfeed.

Most people who have lost weight and kept it off get 60–90 minutes of moderate intensity activity on most days of the week. Moderate intensity activities include biking, brisk walking, and yard work.

Are there medications available to help me lose weight?

If you have tried to lose weight through diet changes and exercise and you still have a BMI above 30 or a BMI of at least 27 with certain medical conditions, such as diabetes or heart disease, your health care provider may suggest medications to help with weight loss. These medications should not be taken once you become pregnant.

When is surgery an option to help me lose weight?

If diet and exercise or medications do not work, a special type of surgery, bariatric surgery, may be an option for people who are very obese (a BMI of 40 or greater or a BMI between 35 and 39 with major health problems caused by obesity).

When can I get pregnant after having weight-loss surgery?

If you have weight-loss surgery, you should delay getting pregnant for 12–24 months after surgery, when you will have the most rapid weight loss. Some types of weight-loss surgery may affect how the body absorbs medications taken by mouth, including birth control pills. You may need to switch to another form of birth control.


Bariatric Surgery: Surgical procedures that cause weight loss for the treatment of obesity.

Body Mass Index (BMI): A number calculated from height and weight that is used to determine whether a person is underweight, normal weight, overweight, or obese.

Cesarean Delivery: Delivery of a baby through incisions made in the mother’s abdomen and uterus.

Deep Vein Thrombosis (DVT): A condition in which a blood clot forms in veins in the leg or other areas of the body.

Gestational Diabetes: Diabetes that arises during pregnancy.

Gestational Hypertension: High blood pressure that starts during the second half of pregnancy.

Macrosomia: A condition in which a fetus grows very large.

Neural Tube Defects: Birth defects that result from incomplete development of the brain, spinal cord, or their coverings.

Obesity: A condition characterized by excessive body fat.

Preeclampsia: A condition of pregnancy in which there is high blood pressure and protein in the urine.

Preterm: Born before 37 weeks of pregnancy.

Stillbirth: Delivery of a dead baby.

Stroke: A sudden interruption of blood flow to all or part of the brain, caused by blockage or bursting of a blood vessel in the brain and often resulting in loss of consciousness and temporary or permanent paralysis.

Ultrasound Exam: A test in which sound waves are used to examine internal structures. During pregnancy, it can be used to examine the fetus.

If you have further questions, contact your obstetrician–gynecologist.

FAQ182: Designed as an aid to patients, this document sets forth current information and opinions related to women’s health. The information does not dictate an exclusive course of treatment or procedure to be followed and should not be construed as excluding other acceptable methods of practice. Variations, taking into account the needs of the individual patient, resources, and limitations unique to the institution or type of practice, may be appropriate.

Copyright June 2013 by the American College of Obstetricians and Gynecologists

American Congress of Obstetricians and Gynecologists
409 12th Street SW, Washington, DC  20024-2188 | Mailing Address: PO Box 70620, Washington, DC 20024-9998