Pregnancy week by week

Obesity is a serious health condition that involves having too much body fat. During pregnancy, obesity can have a major impact on a pregnant person's health. Obesity also can affect the health of an unborn baby, called a fetus. Find out what the risks are and what you can do to boost your chances of a healthy pregnancy.

How is obesity measured?

Healthcare professionals use a measure called body mass index, also known as BMI, to find out if a person has obesity. Obesity involves having a BMI of 30 or higher. BMI looks at weight and height to estimate body fat. To figure out your BMI, divide your weight in pounds by your height in inches squared and multiply by 703. Or divide your weight in kilograms by your height in meters squared. Apps also are available to help you easily calculate your BMI.

People of Asian descent who have a BMI of 23 or higher may have an increased risk of health problems.

Based on: Centers for Disease Control and Prevention

Could having a high BMI affect my ability to get pregnant?

Having a high BMI can lessen the ability to become pregnant, also called fertility. A high BMI can affect the process called ovulation in which an egg is released from an ovary. The higher the BMI, the longer it may take to become pregnant. And that's true even in people who regularly ovulate. A higher BMI also may be linked to a greater risk of a fertility treatment called in vitro fertilization not working.

How might a high BMI affect my pregnancy?

Having a high BMI during pregnancy raises the risk of various health conditions, including:

• Loss of a pregnancy due to miscarriage or stillbirth. There's also a risk of repeated miscarriages.
• Diabetes during pregnancy, also called gestational diabetes.
• A condition called preeclampsia in which a pregnant person has high blood pressure. The pregnant person also may have signs of damage to the kidneys or other organs.
• Heart conditions.
• A serious condition called obstructive sleep apnea in which breathing stops and starts many times during sleep.
• The need for surgery called a C-section to deliver a baby. There's also a higher risk of health concerns linked to a C-section such as wound infections.

How could obesity affect my baby?

Having a high BMI during pregnancy has been linked to higher risks of various health conditions for a baby, including:

• Growth troubles in a fetus called fetal growth restriction.
• Conditions present at birth, also called congenital conditions.
• A larger than average size at birth, also called fetal macrosomia.
• Childhood asthma.
• Childhood obesity.
• Trouble with thinking, learning, memory, judgment or decision-making.
• Taking longer than is typical to reach some milestones in development, also known as developmental delays.

But factors other than a high BMI during pregnancy also might play roles in these health conditions.

How much weight should I gain during pregnancy?

Your healthcare professional helps you manage your weight throughout pregnancy. Your healthcare professional takes into account how much you weighed before pregnancy when helping you decide how much weight to gain.

Guidelines for pregnancy weight gain and obesity include the following:

• Single pregnancy. If you have a BMI of 30 or higher and are carrying one baby, the recommended weight gain is 11 to 20 pounds (about 5 to 9 kilograms).
• Multiple pregnancy. If you have a BMI of 30 or higher and are carrying twins or multiples, the recommended weight gain is 25 to 42 pounds (about 11 to 19 kilograms).

Your healthcare professional might not recommend that you gain a specific amount of weight during pregnancy. Instead, your healthcare professional might talk with you about preventing extra weight gain that could pose health risks.

If I have obesity, will I need special care during pregnancy?

If you have a BMI of 30 or higher, your healthcare professional closely tracks your pregnancy. Your healthcare professional might recommend:

• Early testing for gestational diabetes. For people at average risk of gestational diabetes, a screening test called the glucose challenge often is done between weeks 24 and 28 of pregnancy. If you have a BMI of 30 or higher, your healthcare professional might recommend the screening test at your first prenatal visit. The test measures the body's response to sugar, also called glucose. If your results show that your blood sugar level is within the standard range, you'll likely repeat the test between weeks 24 and 28 of pregnancy. If the results show that your blood sugar level is high, you'll likely need more testing. Your healthcare professional can advise you on how to track and control blood sugar.
• Extra fetal ultrasounds. An ultrasound test helps check a fetus's health. It lets healthcare professionals look at body parts such as the head, heart and brain. A standard fetal ultrasound usually is done between weeks 18 and 20 of pregnancy. But the ultrasound waves that help make the image of the baby don't easily pass through fat tissue in the stomach area. This can make a fetal ultrasound less effective. Sometimes, healthcare professionals recommend doing more than one ultrasound over a period of time. This helps them see as much of the fetus's anatomy as possible. Talk with your healthcare professional about how to get an accurate ultrasound.
• Screening for obstructive sleep apnea. Obstructive sleep apnea happens when the throat muscles relax and block the airway many times during sleep. Pregnant people with this serious condition have higher risks of preeclampsia and other health issues during pregnancy. You'll likely be tested for obstructive sleep apnea at your first prenatal visit. If there's a chance that you have the condition, your healthcare professional may refer you to a sleep medicine specialist. A sleep medicine specialist can find out if you have obstructive sleep apnea and give you treatment if you do.

What steps can I take to boost my odds of a healthy pregnancy?

You can limit the impact of having a high BMI on your health and your baby's health. For example:

• Talk with your healthcare professional before you become pregnant. Make an appointment if you have a BMI of 30 or higher and you're thinking about getting pregnant. During your visit, your healthcare professional might recommend a daily prenatal vitamin. You also may be referred to other healthcare professionals who can help you reach a healthy weight before you become pregnant. For example, you may meet with a registered dietitian.
• Get regular prenatal care. Prenatal visits can help your healthcare team track your health and your baby's health. Tell your healthcare professional about any health conditions you have, such as diabetes, high blood pressure or sleep apnea. Ask what you can do to manage your conditions.
• Eat a healthy diet. Work with your healthcare professional or a registered dietitian to follow a nutritious diet and gain a healthy amount of weight during pregnancy. Keep in mind that during pregnancy, you'll need more folic acid, protein, calcium, iron and other essential nutrients.
• Be physically active. Talk with your healthcare professional about safe ways to stay active during pregnancy. Some good choices might include walking, swimming and doing low-impact aerobics.
• Do not use risky substances. If you smoke, ask your healthcare professional to help you quit. Alcohol and illegal drugs are off-limits too. Get your healthcare professional's OK before you start or stop taking any medicines or supplements.

Obesity during pregnancy can raise the risk of health concerns for you and your baby. Working with your healthcare professional can help you manage your risks and boost your chances of a healthy pregnancy.

Mayo Clinic's Ultimate Guide to Pregnancy

This guide offers research-backed advice to help you and your baby experience a healthy pregnancy, written by some of the world's leading medical experts.

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