Obesity and Pregnancy
Frequently Asked Questions: Pregnancy
Being overweight is defined as having a body mass index (BMI) of 25–29.9. Obesity is defined as having a BMI of 30 or greater. Within the general category of obesity, there are three levels that reflect the increasing health risks that go along with increasing BMI:
- Lowest risk is a BMI of 30–34.9.
- Medium risk is a BMI of 35.0–39.9.
- Highest risk is a BMI of 40 or greater.
You can find out your BMI by using an online BMI calculator on a web site such as http://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm.
Obesity during pregnancy puts you at risk of several serious health problems:
- Gestational diabetes is diabetes that is first diagnosed during pregnancy. This condition can increase the risk of having a cesarean delivery. Women who have had gestational diabetes also have a higher risk of having diabetes in the future, as do their children. Obese women are screened for gestational diabetes early in pregnancy and also may be screened later in pregnancy as well.
- Preeclampsia is a high blood pressure disorder that can occur during pregnancy or after pregnancy. It is a serious illness that affects a woman’s entire body. The kidneys and liver may fail. Preeclampsia can lead to seizures, a condition called eclampsia. In rare cases, stroke can occur. Severe cases need emergency treatment to avoid these complications. The baby may need to be delivered early. Sleep apnea is a condition in which a person stops breathing for short periods during sleep.
- Sleep apnea is associated with obesity. During pregnancy, sleep apnea not only can cause fatigue but also increases the risk of high blood pressure, preeclampsia, eclampsia, and heart and lung disorders.
Obesity increases the risk of the following problems during pregnancy:
- Pregnancy loss—Obese women have an increased risk of pregnancy loss (miscarriage) compared with women of normal weight.
- Birth defects—Babies born to obese women have an increased risk of having birth defects, such as heart defects and neural tube defects.
- Problems with diagnostic tests—Having too much body fat can make it difficult to see certain problems with the baby’s anatomy on an ultrasound exam. Checking the baby’s heart rate during labor also may be more difficult if you are obese.
- Macrosomia—In this condition, the baby is larger than normal. This can increase the risk of the baby being injured during birth. For example, the baby’s shoulder can become stuck during delivery. Macrosomia also increases the risk of cesarean delivery. Infants born with too much body fat have a greater chance of being obese later in life.
- Preterm birth—Problems associated with a woman’s obesity, such as preeclampsia, may lead to a medically indicated preterm birth. This means that the baby is delivered early for a medical reason. Preterm babies are not as fully developed as babies who are born after 39 weeks of pregnancy. As a result, they have an increased risk of short-term and long-term health problems.
- Stillbirth—The higher the woman’s BMI, the greater the risk of stillbirth.
Losing weight before you become pregnant is the best way to decrease the risk of problems caused by obesity. Losing even a small amount of weight (5–7% of your current weight, or about 10–20 pounds) can improve your overall health and pave the way for a healthier pregnancy.
To lose weight, you need to use up more calories than you take in. You can do this by getting regular exercise and eating healthy foods. Your obstetrician may refer you to a nutritionist to help you plan a healthy diet. You also can use the Choose My Plate web site at www.choosemyplate.gov. Increasing your physical activity is important if you want to lose weight. Aim to be moderately active (for example, biking, brisk walking, and general gardening) for 60 minutes or vigorously active (jogging, swimming laps, or doing heavy yard work) for 30 minutes on most days of the week. You do not have to do this amount all at once. For instance, you can exercise for 20 minutes three times a day.
If you have tried to lose weight through diet changes and exercise and you still have a BMI of 30 or greater or a BMI of at least 27 with certain medical conditions, such as diabetes or heart disease, weight-loss medications may be suggested. These medications should not be taken if you are trying to become pregnant or are already pregnant.
Bariatric surgery may be an option for people who are very obese or who have major health problems caused by obesity. 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. If you have had fertility problems, they may resolve on their own as you rapidly lose the excess weight. It is important to be aware of this because the increase in fertility can lead to an unplanned pregnancy. Some types of bariatric 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.
Despite the risks, you can have a healthy pregnancy if you are obese. It takes careful management of your weight, attention to diet and exercise, regular prenatal care to monitor for complications, and special considerations for your labor and delivery.
Finding a balance between eating healthy foods and staying at a healthy weight is important for your health as well as your baby’s health. In the second and third trimesters, a pregnant woman needs an average of 300 extra calories a day—about the amount of calories in a glass of skim milk and half of a sandwich. You can get help with planning a healthy diet by talking to a nutrition counselor. Help also can be found at the Choose My Plate web site, which has a special section for women who are pregnant or breastfeeding (www.choosemyplate.gov/moms-pregnancy-breastfeeding).
If you have never exercised before, pregnancy is a great time to start. Discuss your exercise plan with your obstetrician to make sure it is safe. 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 on most—preferably all—days of the week. Walking is a good choice if you are new to exercise. Swimming is another good exercise for pregnant women. The water supports your weight so you can avoid injury and muscle strain. It also helps you stay cool.
Your weight will be tracked at each prenatal visit. The growth of your baby also will be checked. If you are gaining less than the recommended guidelines, and if your baby is growing well, you do not have to increase your weight gain to catch up to the guidelines. If your baby is not growing well, changes may need to be made to your diet and exercise plan.
Overweight and obese women have longer labors than women of normal weight. It can be harder to monitor the baby during labor. For these reasons, obesity during pregnancy increases the likelihood of having a cesarean delivery. If a cesarean delivery is needed, the risks of infection, bleeding, and other complications are greater for an obese woman than for a woman of normal weight.
Once you are home with your new baby, stick to your healthy eating and exercise habits to reach a normal weight. Breastfeeding is recommended for the first year of a baby’s life. 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 faster than women who do not breastfeed.
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.
Calories: Units of heat used to express the fuel or energy value of food.
Cesarean Delivery: Delivery of a baby through surgical incisions made in the woman’s abdomen and uterus.
Eclampsia: Seizures occurring in pregnancy or after pregnancy and linked to high blood pressure.
Gestational Diabetes: Diabetes that arises during pregnancy.
Macrosomia: A condition in which a fetus has an estimated weight of 4,500 grams (9 pounds 15 ounces) or greater.
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 disorder that can occur during pregnancy or after childbirth in which there is high blood pressure and other signs of organ injury, such as an abnormal amount of protein in the urine, a low number of platelets, abnormal kidney or liver function, pain over the upper abdomen, fluid in the lungs, or a severe headache or changes in vision.
Preterm: Born before 37 weeks of pregnancy.
Sleep Apnea: A disorder characterized by interruptions of breathing during sleep that can lead to other health problems.
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.
Trimesters: The three 3-month periods into which pregnancy is divided.
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. Copyright April 2016 by the American College of Obstetricians and Gynecologists
This information is designed as an educational aid to patients and sets forth current information and opinions related to women’s health. It is not intended as a statement of the standard of care, nor does it comprise all proper treatments or methods of care. It is not a substitute for a treating clinician’s independent professional judgment. Read ACOG’s complete disclaimer.