Reducing the risk for congenital heart defects

March 5, 2021

A teratogen is something that can cause a birth defect or increase the risk of a baby having a birth defects. Certain medicines are teratogens because they can increase the risk of birth defects if they are used during pregnancy. The same is true for alcohol, tobacco and street drugs. Certain health conditions and infections in a pregnant person also can increase the risk of birth defects.

Teratogens can affect parts of a baby’s body as they are forming, such as the heart. A baby’s heart is the first organ to develop. Congenital heart defects (also called CHDs) can happen in the first 6 weeks of pregnancy, sometimes before you even know you’re pregnant. CHDs are heart conditions that a baby is born with. These conditions can affect the heart’s shape or how it works or both. CHDs are the most common type of birth defects.

Experts aren’t sure what causes most CHDs. But these substances can increase the risk of your baby having a CHD.

Certain medicines

While more research is needed in some cases, the use of certain medicines during pregnancy may be linked to heart defects. These include:

  • Isotretinoin. (Absorica®, Amnesteem®, Claravis®, Myorisan®, Zenatane®). This medicine is used to treat a severe type of acne. These medicines are so dangerous for a baby that people who use them have to agree to use birth control while they’re on the medicine so they don’t get pregnant.

Certain medicines used to treat mental health conditions:

  • Venlafaxine (Effexor®)
  • A group of medicines called selective serotonin reuptake inhibitors (SSRIs). These include paroxetine (Paxil®), fluoxetine (Prozac®), and sertraline (Zoloft®).
  • Buproprion (Wellbutrin®). This medicine is also used to help people quit smoking.
  • Lithium
  • Valproate
  • Carbamazepine
  • Lamotrigine
  • Certain groups of medicines used to treat high blood pressure, like ACE inhibitors. High blood pressure is when the force of blood against the walls of the blood vessels is too high. It can stress your heart and cause problems during pregnancy.
  • Statins. This group of medicines is used to treat high cholesterol. Cholesterol is a substance in your blood. Too much cholesterol can increase your risk of heart disease.
  • Certain medicines used to treat epilepsy. This includes valproic acid (Depakote®) and possibly other medicines for epilepsy. Epilepsy is a seizure disorder that affects how the nerve cells in your brain work.
  • Certain antibiotics. These include nitrofurantoin and medicines called sulfonamides, including trimethoprim-sulfamethaxole (BactrimTM).
  • Methotrexate. This medicine is used to treat arthritis. Arthritis is a condition that affects the body’s joints.
  • Sulfasalazine (Asacol®). This medicine is used to treat ulcerative colitis and some types of arthritis. Ulcerative colitis is a disease that affects the body’s digestive tract.
  • Thalidomide (Thalomid®). This medicine is used to treat certain skin conditions, cancers and complications from HIV (stands for human immunodeficiency virus). HIV attacks the body’s immune system and is the virus that causes AIDS.
  • Bronchodilators. These medicines are used to treat asthma. Asthma is a health condition that affects the body's airways and can cause breathing problems.

If you are taking any of these medicines, make sure you talk to your provider before trying to get pregnant.

Alcohol, tobacco and drugs

Substances such as alcohol, tobacco and drugs can cause problems for you and your baby during pregnancy. Here’s how they are linked to CHDs.

  • Drinking alcohol. No amount of alcohol is safe during pregnancy. Drinking alcohol during pregnancy can cause many problems, including increasing the risk of birth defects such as heart defects, hearing problems and vision problems.
  • Tobacco use. People who smoke anytime during the month before their pregnancy or during the first 3 months of pregnancy are more likely to have a baby with a CHD than those who don’t smoke.
  • Drug use. Using drugs such as opioids during pregnancy has been linked to an increased risk of birth defects, including CHDs.

Certain health conditions and infections

Having one of these conditions may increase your risk of having a baby with a CHD.

  • Preexisting diabetes (also called type 1 or type 2 diabetes). This is a medical condition in which your body has too much sugar (called glucose) in your blood. Preexisting means you had diabetes before you got pregnant. High blood sugar can be harmful to your baby during the first few weeks of pregnancy when his heart begins to form.
  • Rubella (also called German measles). This is an infection that causes mild flu-like symptoms and rash on the skin. Having rubella during pregnancy can cause problems with your baby’s heart development.
  • Cytomegalovirus (also called CMV). This is a common viral infection that most of us get at some point in our lives, often during childhood. Having CMV during pregnancy can cause problems for some babies, including an increased risk for CHDs.
  • Lupus (also called systemic lupus erythematosus or SLE). Lupus is an autoimmune disease. This is a health condition that happen when antibodies (cells in the body that fight off infections) attack healthy tissue by mistake. Lupus can damage the joints, skin, kidneys, heart, lungs and other body parts.
  • Maternal phenylketonuria (also called PKU). PKU is a condition in which your body can’t break down an amino acid called phenylalanine. Amnio acids help build protein in your body. Without treatment, phenylalanine builds up in the blood and causes health problems.
  • Obesity (being very overweight). If you’re affected by obesity, you have a higher weight  and your body mass index (BMI) is 30 or higher. To find out your BMI, go to

Reducing the risk of CHDs 
Here are some things you can do to reduce the risk of CHDs  and increase your chances of having a healthy pregnancy and a healthy baby.

  • Get a preconception checkup. This can help your health care provider make sure your body is ready for pregnancy.
  • Take folic acid. Folic acid may help prevent heart defects. Take a vitamin supplement with 400 micrograms of folic acid in it every day, even if you’re not trying to get pregnant.
  • Tell your provider about any medicines you take before you get pregnant. This includes prescription medicinesover the counter (OTC) medicines, herbal products and supplements. If the medicine you take may be harmful to your baby, you may be able to change to one that’s safer. But some medicines may be critical to your own health. Don’t start or stop taking any medicine without talking to your provider first.
  • Get to a healthy weight before pregnancy. If you are a person who is overweight or affected by obesity, losing even a small amount of weight (about 10 to 20 pounds) can improve your health and help you have a healthier pregnancy.
  • Don’t smoke, drink alcohol or take drugs during pregnancy. Talk to your health care provider if you need help to quit.
  • Get caught up on vaccinations before you get pregnant. Your provider can check to see if you are immune from rubella. Immune means you are protected from an infection. If you are not immune and you are not pregnant yet, you can get the MMR vaccine. The MMR vaccine protects you from measles, mumps and rubella. Wait 4 weeks after you get an MMR vaccination before you get pregnant.
  • Protect yourself from viruses like CMV. Here are some things you can do:
    • If you’re around children, wash your hands well after being in contact with their body fluids. For example, wash your hands after changing diapers, wiping noses and picking up toys.
    • Don’t kiss young children on the mouth or cheek.
    • Don’t share food, cups or utensils with young children or with anyone who may have CMV.
    • If your partner has CMV, use a latex condom during sex.
  • Manage any health conditions you have.
    • If you have diabetes, work with your provider to control your blood sugar before and during pregnancy. Get your diabetes under control 3 to 6 months before you start trying to get pregnant.
    • If you have lupus, work with your provider to get your condition under control 6 months before you get pregnant.
    • If you have PKU, work with your provider to get your condition under control at least 3 months before you get pregnant. Most pregnant people who have  PKU can have healthy babies if they follow a special mean plan that’s low in phenylalanine.

Learn more about congenital heart defects.