Obesity and Pregnancy

Being overweight is defined as having a body mass index (BMI) of 25 to 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:

• Obesity category I—BMI of 30 to 34.9

• Obesity category II—BMI of 35 to 39.9

• Obesity category III—BMI of 40 or greater

You can find out your BMI by using an online BMI calculator.

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

• Gestational hypertension—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 form of gestational hypertension that usually happens in the second half of pregnancy or soon after childbirth. This condition can cause your kidneys and liver to fail. In rare cases, seizures, heart attack, and stroke can happen. Other risks include problems with the placenta and growth problems for the fetus.

• Gestational diabetes—High levels of glucose (blood sugar) during pregnancy increase the risk of having a very large baby. This also increases the chance of cesarean birth. If you have had gestational diabetes, you and your children may have a higher risk of diabetes mellitus in the future.

• Obstructive sleep apnea—Sleep apnea is a condition in which a person stops breathing for short periods during sleep. During pregnancy, sleep apnea can cause fatigue and increase the risk of high blood pressure, preeclampsia, and heart and lung problems.

[What’s the Concern About High Blood Pressure During Pregnancy? An Ob-Gyn Explains.]

Obesity increases the risk of the following problems during pregnancy:

• Birth defects—Babies born to women who have obesity have an increased risk of having birth defects, such as heart defects and neural tube defects (NTDs).

• Problems with diagnostic tests—Having too much body fat can make it difficult to see certain problems with the fetus’s anatomy on an ultrasound exam. Checking the fetus’s heart rate during labor may also be more difficult.

• Macrosomia—In this condition, the fetus is larger than normal. This can increase the risk of injury during birth. For example, the fetus’s shoulder can get stuck after the head is delivered. Macrosomia also increases the risk of cesarean birth. Infants born with too much body fat have a greater chance of having obesity later in life.

• Preterm birth—Problems associated with 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, preterm babies have an increased risk of short-term and long-term health problems.

• Stillbirth—The higher your BMI, the greater the risk of stillbirth.

Losing weight before you get pregnant is the best way to decrease the risk of problems caused by obesity. If you’re overweight, losing even a small amount of weight can improve your overall health and pave the way for a healthier pregnancy.

Weight loss happens when you use up more calories than you take in. You can do this by getting regular exercise and eating healthy foods. Still, losing weight can be difficult for many people. Research on the best way to lose weight continues to evolve.

Your obstetrician–gynecologist (ob-gyn) may refer you to a nutritionist to help you plan a healthy diet. Also, the MyPlate website from the U.S. Department of Agriculture has information about healthy eating while pregnant or breastfeeding.

Increasing your physical activity is important if you want to lose weight. Aim to be moderately active for 60 minutes or vigorously active for 30 minutes on most days of the week. You do not have to do this amount all at once. For example, you can exercise for 20 minutes three times a day. Pick something you like to do. Moderate-intensity activities include biking, brisk walking, and gardening. Vigorous-intensity activities include jogging, swimming laps, and heavy yard work.

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 get pregnant or are already pregnant.

Bariatric surgery may be an option for people who have a BMI of 40 or greater or a BMI between 35 and 39 with major health problems caused by obesity. If you have weight loss surgery, delay getting pregnant for 12 to 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’s 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.

Most people who have had bariatric surgery do well during pregnancy. When you get pregnant after the surgery, your ob-gyn may monitor you for vitamin deficiencies. It may also be suggested that you work with a nutritionist to learn how to meet your nutritional needs during pregnancy.

Despite the risks of obesity, you can still have a healthy pregnancy. 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.

While you’re pregnant, the food you eat fuels your body and helps your fetus grow. Finding a balance between eating healthy foods and staying at a healthy weight is important for your health and your fetus's health. In the second and third trimesters, you need 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. You can also find help at the MyPlate website from the U.S. Department of Agriculture.

If you have never exercised before, pregnancy is a great time to start. Discuss your exercise plan with your ob-gyn to make sure it’s 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 or all days of the week.

Walking is a good choice if you are new to exercise. Swimming is another good exercise during pregnancy. The water supports your weight so you can avoid injury and muscle strain. It also helps you stay cool. Read Exercise During Pregnancy for more advice.

At your first prenatal visit, your BMI should be calculated. A recommendation should be made about the amount of weight you should gain throughout pregnancy.

Your weight should be checked at each prenatal visit. The growth of your fetus is also checked. If you are gaining less than the recommended guidelines, and if your fetus is growing well, you do not have to increase your weight gain to catch up to the guidelines. If your fetus is not growing well, changes may need to be made to your diet and exercise plan.

Pain relief during labor and delivery may take special planning if you have obesity. Before you have your baby, you may meet with a health care professional to discuss your pain relief options.

Also, women who are overweight  have longer labors than women of normal weight. It can be harder to monitor the fetus during labor. For these reasons, obesity during pregnancy increases the likelihood of having a cesarean birth.

If a cesarean birth is needed, obesity can increase the risks of infection, bleeding, and other complications. Steps can be taken to reduce your risk of these complications. For example, you may wear inflatable cuffs on your legs before, during, and after surgery to help prevent blood clots.

Once you are home with your new baby, try to 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. Breastfeeding is good for you and your baby. It may also 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.

It can be hard to lose the weight you gained during pregnancy. Weight can add up with each pregnancy. It helps to give yourself enough time to recover from pregnancy and lose excess weight before you get pregnant again. Read Postpartum Birth Control to learn more.

Bariatric Surgery: Surgical procedures that cause weight loss. These procedures are used to treat obesity.

Birth Defects: Physical problems that are present at birth.

Body Mass Index (BMI): A number calculated from height and weight. BMI 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 Birth: Birth of a fetus from the uterus through an incision (cut) made in the woman’s abdomen.

Complications: Diseases or conditions that happen as a result of another disease or condition. An example is pneumonia that occurs as a result of the flu. A complication also can occur as a result of a condition, such as pregnancy. An example of a pregnancy complication is preterm labor.

Diabetes Mellitus: A condition in which the levels of sugar in the blood are too high.

Fetus: The stage of human development beyond 8 completed weeks after fertilization.

Gestational Diabetes: Diabetes that starts during pregnancy.

Gestational Hypertension: High blood pressure that is diagnosed after 20 weeks of pregnancy.

Glucose: A sugar in the blood that is the body’s main source of fuel.

High Blood Pressure: Blood pressure above the normal level. Also called hypertension.

Kidneys: Organs that filter the blood to remove waste that becomes urine.

Macrosomia: A condition in which a fetus grows more than expected, often weighing more than 8 pounds and 13 ounces (4,000 grams).

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

Obesity: A condition characterized by excessive body fat.

Obstetrician–Gynecologist (Ob-Gyn): A doctor with special training and education in women’s health.

Obstructive Sleep Apnea: A serious sleep disorder that causes a person to have brief pauses in breathing during sleep.

Placenta: An organ that provides nutrients to and takes waste away from the fetus.

Preeclampsia: A disorder that can occur during pregnancy or after childbirth in which there is high blood pressure and other signs of organ injury. These signs include 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.

Prenatal Care: A program of care for a pregnant woman before the birth of her baby.

Preterm: Less than 37 weeks of pregnancy.

Stillbirth: Birth of a dead fetus.

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. A stroke often results in loss of consciousness and temporary or permanent paralysis.

Ultrasound Exam: A test in which sound waves are used to examine inner parts of the body. During pregnancy, ultrasound can be used to check the fetus.