Reducing Risks of Birth Defects
Frequently Asked Questions: Pregnancy
A birth defect is a condition that is present at birth. Some birth defects can be seen right after the baby is born, such as a clubfoot or extra fingers or toes. Special tests may be needed to find others, such as heart defects or hearing loss. Some birth defects are not noticed until later in life.
Some birth defects are caused by genes that can be passed from parents to children. Others result from a problem with chromosomes. A small number of birth defects are caused by exposure during pregnancy to certain medications, infections, and chemicals. For many birth defects, the cause is not known.
What can I do before or during pregnancy to decrease my risk of having a baby with certain birth defects?
Most birth defects cannot be prevented because their cause is not known. For a few birth defects, you may be able to decrease your risk by taking certain steps:
- See your doctor before getting pregnant.
- Know your risk factors.
- Take a daily multivitamin before and during pregnancy.
- Maintain a healthy weight.
- Use medications wisely.
- Take care of medical conditions before pregnancy.
- Do not use alcohol, marijuana, illegal drugs, or prescription drugs for a nonmedical reason.
- Prevent infections.
- Avoid known harmful agents.
Scheduling a health care visit before getting pregnant is a good idea. You can get advice about diet and exercise from your obstetrician–gynecologist (ob-gyn) or other health care professional. You can talk about whether you have any factors that increase the risk of having a child with a birth defect. If you have a medical condition, you can talk about any special care that you may need before or during pregnancy.
You may be at an increased risk of having a baby with a birth defect if you
- are older
- have a family or personal history of birth defects
- have had a child with a birth defect
- use certain medicines around the time you become pregnant
- have a medical condition such as diabetes mellitus or obesity
- use recreational drugs or drink alcohol during pregnancy
If you have any risk factors, your ob-gyn or other health care professional may recommend special tests or other steps that may help reduce your risk. For example, if you have a personal or family history of birth defects, genetic counseling and testing may be recommended.
Prenatal vitamin supplements contain the recommended amounts of the vitamins and minerals you will need during your pregnancy, including
- vitamins A, C, and D
- folic acid
- minerals such as iron
Taking 400 micrograms (mcg) of folic acid daily for at least 1 month before pregnancy and during pregnancy helps prevent major birth defects called neural tube defects (NTDs). These are defects of the brain and spine of the fetus. Most prenatal and “women’s formula” multivitamin supplements contain 400–800 mcg of folic acid.
A few medications have been linked to birth defects. You should tell anyone who prescribes drugs for you that you are pregnant or thinking about getting pregnant. This includes doctors you may see for dental care, mental health care, or other nonpregnancy problems. Also, check with your ob-gyn or other health care professional before taking any over-the-counter drug, such as pain relievers, laxatives, cold or allergy remedies, vitamins, herbal products, and skin treatments. A good source for information about the safety or risk of specific drugs during pregnancy is the website of the Organization of Teratology Information Specialists: www.mothertobaby.org.
Women who are obese (defined as having a body mass index [BMI] of 30 or greater) when they get pregnant have an increased risk of having babies with certain birth defects than women who are a normal weight. Among the most common obesity-related birth defects are NTDs, heart defects, and cleft palate. If you are planning a pregnancy, the best way to prevent problems caused by obesity is to be at a normal weight before you get pregnant.
I have certain medical conditions. Why is it important to talk with my ob-gyn or other health care professional if I am thinking about getting pregnant?
Some medical conditions—such as diabetes, high blood pressure, and seizure disorders—may increase the risk of having a baby with certain birth defects. If you have a medical condition, see your ob-gyn or other health care professional to discuss any changes you need to make in your diet, medication, or other areas to bring the condition under control before you try to get pregnant.
Alcohol can interfere with the normal growth of the fetus and cause birth defects. When a woman drinks during pregnancy, her fetus can develop physical, intellectual, behavioral, and learning disabilities that can last a lifetime. It is best not to drink at all during pregnancy. If it is hard for you to stop drinking, talk with your ob-gyn or other health care professional or contact Alcoholics Anonymous on its website: www.aa.org.
Using substances—including heroin, cocaine, methamphetamines, and prescription drugs taken for a nonmedical reason—is a widespread problem in the United States. Using illegal drugs early in pregnancy can cause birth defects and miscarriage. During the later weeks of pregnancy, illegal drugs can interfere with the growth of the fetus and cause preterm birth and fetal death. Infants born to women who used illegal drugs during pregnancy may need specialized care after birth. If you need help quitting illegal drugs, you can find resources at the website of Narcotics Anonymous: www.na.org.
Recreational marijuana used during pregnancy is associated with attention and behavioral problems in children. Marijuana may increase the risk of stillbirth and the risk that babies will be smaller than babies who are not exposed to marijuana before birth. Medical marijuana also should be avoided. The American College of Obstetricians and Gynecologists recommends that pregnant women and those planning to become pregnant not use any form of marijuana. You and your ob-gyn or other health care professional can discuss alternative treatments that will be safe for your fetus.
Opioids are a type of medication that relieves pain. Doctors may prescribe opioids for people who have had surgery, dental work, or an injury. Prescribed opioids include oxycodone, hydromorphone, hydrocodone, and codeine. When taken under a doctor’s care, opioids are safe for both you and your fetus. It is important to take the medication only as prescribed.
Most people who use a prescription opioid have no trouble stopping their use, but some people develop an addiction. Misusing opioids during pregnancy can increase the risk of serious complications, including preterm birth, stillbirth, and problems with the placenta and fetal growth. If you need help with an opioid addiction, you can find resources at the website of the Substance Abuse and Mental Health Services Administration (SAMHSA): www.samhsa.gov. SAMHSA also has a 24 hour treatment referral line: 800-662-HELP (4357).
What infections should I be concerned about and how can I reduce my risk of getting them during pregnancy?
Some infections can increase the risk of birth defects and other problems during pregnancy for you and your fetus:
- Rubella (German measles) is a viral infection that usually causes a mild rash and a low fever. Having rubella during pregnancy can cause miscarriage or result in deafness, intellectual disability, heart defects, and blindness in a newborn. There is a vaccine against rubella, but it is not recommended for pregnant women. If you have not already had the disease or been vaccinated, you should be vaccinated against rubella and wait at least 1 month before becoming pregnant.
- Toxoplasmosis is a disease caused by a parasite that lives in soil. You can become infected by eating raw or undercooked meat or unwashed vegetables or by coming into contact with animal feces, especially from cats that go outdoors. If you are infected for the first time while you are pregnant, you can pass the disease on to your baby. Toxoplasmosis can cause birth defects, including hearing loss, vision problems, and intellectual disability. Make sure that you eat well-cooked meat and wear gloves while gardening or handling unwashed vegetables. If you have an outdoor cat that uses a litter box, have someone else empty it. If you must empty the litter box, use gloves and wash your hands well after doing so.
- Sexually transmitted infections (STIs) can cause serious birth defects. Treating an STI—preferably before you get pregnant—may prevent or reduce harm to the fetus.
- Cytomegalovirus (CMV) is a common viral infection. Most CMV infections cause no significant problems. If you are infected for the first time when you are pregnant, CMV can infect the fetus. In a small number of cases, the infection can cause intellectual disability, hearing loss, and vision problems. CMV can be spread by contact with an infected child’s urine or other body fluids. Pregnant women who work with young children, such as day care workers or health care workers, should take steps to prevent infection, including wearing gloves when changing diapers. Frequent handwashing also is recommended. Pregnant women with young children at home also are at risk and should take these steps.
- Zika virus has been found in South America, Central America, and North America. Infection with the virus during pregnancy can cause serious birth defects, including microcephaly (a birth defect in which a baby’s head and brain are smaller than normal) and other brain abnormalities. These birth defects can lead to lifelong problems, including seizures, feeding problems, hearing loss, vision problems, and learning difficulties. There still are many things that researchers do not know about Zika virus.
Zika virus can be transmitted through the bite of an infected mosquito or through sex with an infected partner. To avoid Zika virus, take strict steps to avoid mosquito bites. If your male partner lives in or travels to an area where Zika virus is spreading, use a condom each time you have sex. Do not travel to areas where Zika virus is known to be active.
If you or your partner must travel to an area where Zika virus is active, strictly follow these four steps to prevent mosquito bites:
- Use EPA-registered bug spray with DEET, picaridin, IR3535, oil of lemon eucalyptus, paramenthane-diol, or 2-undecanone. Used as directed, these sprays are safe for pregnant and breastfeeding women.
- Wear long-sleeved shirts and long pants.
- Treat clothing and gear with permethrin or buy permethrin-treated items.
- Stay in air-conditioned or screened-in areas during the day and at night. Follow these steps at all times. Mosquitoes are active during the day and night.
A few precautions that are recommended for all pregnant women include the following:
- Limit your exposure to mercury by not eating bigeye tuna, king mackerel, marlin, orange roughy, shark, swordfish, or tilefish. Limit eating white (albacore) tuna to 6 ounces a week. You do not have to avoid all fish during pregnancy. In fact, fish and shellfish are nutritious foods with vital nutrients for a pregnant woman and her fetus.Be sure to eat at least 8–12 ounces of low-mercury fish and shellfish per week.
- Avoid exposure to lead. Lead can be found in old paint, construction materials, alternative medicines, and items made in foreign countries, such as jewelry and pottery.
- Avoid taking high levels of vitamin A. Very high levels of vitamin A have been linked to severe birth defects. You should consume no more than 10,000 international units of vitamin A a day.
Birth Defect: A physical problem that is 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.
Chromosomes: Structures that are located inside each cell in the body. They contain the genes that determine a person’s physical makeup.
Cleft Palate: A birth defect that causes an opening or split in the roof of the mouth.
Clubfoot: A birth defect in which the foot is misshaped and twisted out of position.
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.
Cytomegalovirus (CMV): A virus that can be transmitted to a fetus if a woman becomes infected during pregnancy. CMV can cause hearing loss, mental disability, and vision problems in newborns.
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.
Folic Acid: A vitamin that reduces the risk of certain birth defects when taken before and during pregnancy.
Genes: Segments of DNA that contain instructions for the development of a person’s physical traits and control of the processes in the body. The gene is the basic unit of heredity and can be passed from parent to child.
High Blood Pressure: Blood pressure above the normal level. Also called hypertension.
Microcephaly: A birth defect in which a baby’s head and brain are smaller than normal. Babies with microcephaly may have seizures, developmental delays, mental disability, vision and hearing problems, and problems with balance and movement.
Miscarriage: Loss of a pregnancy that is in the uterus.
Neural Tube Defects (NTDs): Birth defects that result from a problem in development of the brain, spinal cord, or their coverings.
Nutrients: Nourishing substances found in food, such as vitamins and minerals.
Obesity: A condition characterized by excessive body fat.
Obstetrician–Gynecologist (Ob-Gyn): A doctor with special training and education in women’s health.
Opioids: Drugs that decrease the ability to feel pain.
Preterm: Less than 37 weeks of pregnancy.
Rubella: A virus that can be passed to the fetus if a woman becomes infected during pregnancy. The virus can cause miscarriage or severe birth defects.
Seizure Disorders: Any condition that causes seizures, which cause changes in movement, consciousness, mood, or emotions. Epilepsy is one kind of seizure disorder.
Sexually Transmitted Infections (STIs): Infections that are spread by sexual contact. Infections include chlamydia, gonorrhea, human papillomavirus (HPV), herpes, syphilis, and human immunodeficiency virus (HIV, the cause of acquired immunodeficiency syndrome [AIDS]).
Stillbirth: Birth of a dead fetus.
Toxoplasmosis: An infection caused by Toxoplasma gondii, an organism that may be found in raw meat, garden soil, and cat feces (stool). This infection can harm a fetus.
Vaccine: A substance that helps the body fight disease. Vaccines are made from very small amounts of weak or dead agents that cause disease (bacteria, toxins, and viruses).
Zika: A disease caused by the Zika virus, which is spread through mosquito bites.
If you have further questions, contact your obstetrician–gynecologist.
FAQ146: This information was 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. Please check for updates at www.acog.org to ensure accuracy.
Copyright October 2019 by the American College of Obstetricians and Gynecologists. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, posted on the internet, or transmitted, in any form or by any