Harmful substances during pregnancy—such as alcohol, certain medications, or radiation—can deeply affect an unborn baby’s development. Understanding how to manage and prevent exposure to these risks is essential for protecting the health of both mother and child.

How We Protect Developing Babies from Harmful Exposures

When a woman is pregnant, the care she receives focuses on protecting her developing baby from anything that might interfere with normal growth. The goal of managing fetal exposure is not just to treat problems after they occur, but to prevent them in the first place. This means identifying potential dangers early, avoiding harmful substances, and making informed decisions about necessary medical procedures. Because some exposures can have lifelong effects on a child’s brain development, physical growth, and overall health, prevention and careful monitoring are the cornerstones of protecting unborn babies.

Treatment approaches depend heavily on what the baby has been exposed to, when in the pregnancy the exposure happened, and how much exposure occurred. For some harmful substances like alcohol, there is no known safe amount during pregnancy, so the only treatment is complete avoidance. For others, such as certain medications or medical imaging tests that use radiation, healthcare providers must carefully weigh the benefits against potential risks. The stage of pregnancy matters enormously—the same exposure might cause severe problems during one period of development but have minimal impact at another time.

There are established guidelines from medical organizations about how to handle different types of exposures, and ongoing research continues to explore new ways to minimize harm. Some treatments focus on early diagnosis and intervention after exposure has occurred, while others emphasize screening pregnant women to identify risks before problems develop. Clinical trials are also investigating innovative approaches to protect fetuses when exposure to certain substances is medically necessary.

Standard Approaches to Managing Harmful Exposures

The foundation of protecting babies from harmful exposures during pregnancy starts well before any exposure occurs. Healthcare providers recommend that women who are planning to become pregnant schedule a visit with their doctor or other healthcare professional. During this visit, they discuss any medications the woman is taking, review her medical history, and talk about lifestyle factors that could affect a pregnancy. This preconception counseling allows adjustments to be made before a baby begins developing, which is particularly important because many women don’t realize they’re pregnant during the earliest and most vulnerable weeks of fetal development.^[21]

One of the most important preventive measures is taking a daily multivitamin containing folic acid, which is a B vitamin crucial for proper development of the baby’s brain and spine. The recommended amount is 400 micrograms daily, starting at least one month before pregnancy and continuing throughout pregnancy. Folic acid helps prevent serious birth defects called neural tube defects, which affect the brain and spinal cord. Most prenatal vitamins contain the right amount of folic acid along with other important nutrients like iron, calcium, and vitamins A, C, and D.^[21]

Managing Alcohol Exposure

Alcohol exposure during pregnancy causes a range of conditions known as fetal alcohol spectrum disorders (FASD). The most severe form is fetal alcohol syndrome (FAS), which results in permanent physical, behavioral, and cognitive impairments. When a pregnant woman drinks alcohol, it passes directly through her bloodstream to the baby via the umbilical cord. The developing fetus cannot break down alcohol the same way an adult body does, so it stays in the baby’s system longer and interferes with the development of the brain and other vital organs.^[1][4]

Unfortunately, there is no cure for fetal alcohol syndrome or other conditions on the FASD spectrum because the damage occurs during critical periods of development and is permanent. Studies show that between 1% and 5% of U.S. first-grade children have FASD, and these conditions last a lifetime. The effects can include distinctive facial features (small eyes, thin upper lip, flat nose bridge), slow growth before and after birth, small head and brain size, heart and kidney problems, vision or hearing issues, and difficulties with learning, memory, attention, behavior, and daily functioning.^[1][2]

Because fetal alcohol syndrome cannot be treated or reversed, the entire focus is on prevention. Complete abstinence from alcohol during pregnancy is the only way to prevent FASD. This includes all types of alcoholic beverages—wine, beer, hard cider, and liquor all carry the same risk. Research indicates that binge drinking and heavy drinking put a developing baby at the greatest risk for severe problems, but even smaller amounts can cause harm. Alcohol can disrupt development at any stage, even before a woman knows she is pregnant.^[1][5]

When fetal alcohol syndrome is suspected in a child, early diagnosis and intervention services can help improve functioning and quality of life. A healthcare professional with expertise in FASD examines the child’s physical features, assesses growth patterns, and evaluates developmental progress in thinking, learning, language, and behavior. The diagnosis involves reviewing the mother’s drinking history during pregnancy, observing typical facial features associated with FAS, and ruling out other conditions with similar symptoms. Treatment focuses on managing symptoms and may include special education services, behavioral therapy, medications for specific problems like attention issues, and support services for families.^[13][4]

For pregnant women who are struggling with alcohol use, getting help is crucial. Resources include talking with a healthcare provider, contacting local Alcoholics Anonymous groups, or reaching out to alcohol treatment centers. The Substance Abuse and Mental Health Services Administration (SAMHSA) provides a treatment facility locator to help people find programs in their area. It’s never too late during pregnancy to stop drinking—stopping alcohol use at any point will improve the baby’s health and well-being.^[5]

Handling Radiation Exposure

Medical imaging tests that use ionizing radiation—such as X-rays, CT scans, and certain nuclear medicine procedures—require careful consideration during pregnancy because radiation can potentially harm a developing fetus. However, it’s important to understand that most diagnostic imaging procedures expose the fetus to very low doses of radiation that are unlikely to cause problems. The key principle is to keep radiation exposure “as low as reasonably achievable” (ALARA) while still getting the medical information needed to care for the mother.^[3][7]

Healthcare providers use specific guidelines to determine when imaging is necessary during pregnancy. In the United States, background radiation exposure from natural sources is approximately 3.1 mSv per year for everyone. The U.S. Nuclear Regulatory Commission recommends that total fetal exposure during the entire pregnancy should be less than 5.0 mSv (500 mrem). Radiation doses below 50 mGy are considered safe and unlikely to cause harm to the fetus. Doses between 50 and 100 mGy fall into an uncertain range where effects are unclear, while doses above 100 mGy, particularly above 150 mGy, are the levels at which negative effects on the fetus may begin to occur.^[3][9]

The effects of radiation on a fetus depend on three critical factors: the dose of radiation received, the stage of pregnancy when exposure occurs, and the specific body area being imaged. The developing baby is most vulnerable during two key periods: organogenesis (two to seven weeks after conception), when the body’s organs are forming, and the early fetal period (eight to 15 weeks after conception), when the brain is developing rapidly. During organogenesis, radiation exposure above certain thresholds can cause malformations of body parts. During the early fetal period, higher radiation doses may affect brain development and potentially cause intellectual disabilities.^[7][3]

Most of what we know about high-dose radiation effects on fetuses comes from observations of people exposed to the atomic bombs in Hiroshima and Nagasaki, Japan, and the Chernobyl nuclear disaster. These events revealed that very high radiation exposures can cause pregnancy loss (most often when exposure happens in the first two weeks), malformations during organogenesis, developmental delays, and an increased risk of cancer later in life. The cancer risk from radiation is considered a stochastic effect, meaning it can potentially occur at any level of exposure, though the probability increases with higher doses.^[3][9]

When a pregnant woman needs diagnostic imaging, healthcare providers carefully select the test that provides the best medical information with the lowest radiation exposure. Importantly, studies show that noncancer health effects have not been detected at any stage of pregnancy after exposure to ionizing radiation of less than 0.05 Gy (5 rad). This means that single diagnostic imaging procedures—such as a chest X-ray or even a CT scan of an area away from the abdomen—typically deliver doses well below levels known to cause harm.^[7][6]

Nonionizing radiation, which includes ultrasound, magnetic resonance imaging (MRI), microwaves, and radio frequency waves, works differently from ionizing radiation. These forms of energy do not alter cell structure in the same damaging way. Extensive research shows that ultrasound examination during pregnancy is safe when medically indicated and performed using appropriate settings. Ultrasound uses sound waves rather than radiation to create images, making it the preferred imaging method during pregnancy whenever it can provide the needed information.^[7][14]

If a pregnant woman requires imaging that uses ionizing radiation, several techniques help minimize fetal exposure. These include shielding the abdomen and pelvis when possible, adjusting the imaging equipment settings to use the lowest effective dose, limiting the number of images taken, and choosing alternative imaging methods when available. When multiple imaging procedures are needed or when therapeutic radiation treatment is being considered, a subspecialist in dosimetry (radiation measurement) should be consulted to calculate the estimated fetal radiation dose as accurately as possible.^[6][7]

Healthcare providers counsel pregnant women that radiation exposure from a single diagnostic imaging procedure does not increase the risk of fetal abnormalities or pregnancy loss. The benefits of obtaining crucial diagnostic information typically outweigh the very small theoretical risks from low-dose medical radiation. However, diagnostic studies should not be avoided out of fear when they can significantly change patient management—both mother and baby benefit when medical decisions are based on complete and accurate information.^[7][6]

Medication Safety During Pregnancy

Teratogens are substances that interfere with normal fetal development and cause congenital disabilities. Many medications fall into this category, which is why careful attention to medication use is essential during pregnancy. The U.S. Food and Drug Administration (FDA) previously used a simple letter-based system (Categories A, B, C, D, and X) to classify pregnancy risks of medications. However, this system oversimplified complex information, so a newer approach called the Pregnancy and Lactation Labeling Rule (PLLR), implemented in 2015, now provides healthcare providers with more detailed, context-specific information to help them make better decisions when treating pregnant or breastfeeding women.^[12][20]

The danger posed by medication exposure during pregnancy depends on several factors: the specific drug and its mechanism of action, how long the exposure lasted, the dosage or quantity taken, the gestational age of the fetus when exposure occurred, and hereditary factors that might make certain babies more vulnerable. Some medications are particularly risky during specific periods of pregnancy. For example, certain antiepileptic drugs can cause birth defects if taken during the first trimester when organs are forming, but may be medically necessary for the mother’s health to prevent seizures.^[12][20]

Healthcare providers must carefully weigh the benefits and risks when prescribing medications during pregnancy. Sometimes the risk of not treating a condition is greater than the potential risk to the fetus from medication. For instance, a woman with severe epilepsy needs her anti-seizure medication even though it carries some risk to the baby, because uncontrolled seizures pose serious dangers to both mother and child. Similarly, women with diabetes, high blood pressure, thyroid disorders, or other chronic conditions often need continued treatment during pregnancy, though the specific medications may need to be changed to safer alternatives.^[12]

Pregnant women should inform their healthcare provider about all medications they take, including prescription drugs, over-the-counter medications, herbal supplements, and vitamins. They should read labels carefully and, when in doubt about whether something is safe, should contact their healthcare provider before taking it. Some medications that seem harmless can be problematic—for example, high doses of vitamin A, commonly found in skincare products, can cause birth defects. Other concerning medications include certain antimicrobials, anticoagulants (blood thinners), and antithyroid medications.^[12][20]

Other Substance Exposures

Cigarette smoking during pregnancy significantly harms the developing baby. Smoking is associated with fetal growth restriction (the baby grows more slowly than normal), premature birth, miscarriage, and various developmental problems. Smoke affects the baby’s delicate lung tissue and brain development. The chemicals in cigarettes reduce the amount of oxygen reaching the baby and interfere with normal cell growth and function. Pregnant women who smoke should seek help to quit, as stopping at any point in pregnancy improves outcomes for the baby.^[12][20]

Recreational drugs—including cocaine, methamphetamines, heroin, and marijuana—are also harmful during pregnancy. These substances can cause low birth weight, heart problems, developmental delays, and neonatal abstinence syndrome, a condition where babies go through drug withdrawal after birth. Approximately 5% of pregnant women use these substances. Sharing needles also puts both mother and baby at risk for serious infections like HIV and hepatitis. Resources for substance abuse treatment should be accessed as early as possible during pregnancy.^[12][20]

Lead exposure during pregnancy deserves special attention because lead stored in a mother’s bones from past exposures can be released into her bloodstream during pregnancy and passed to the baby. Lead crosses the placenta and accumulates in the developing baby’s bones and organs, potentially causing brain development problems, premature birth, and low birth weight. Pregnant women should avoid renovation of older homes (built before 1978) where lead paint may be present, use only cold tap water for drinking and cooking, avoid certain folk medicines and cosmetics that may contain lead, and ensure anyone working with lead changes clothes and showers before coming home.^[23]

Emerging Research and Clinical Trials

Because pregnant women have historically been excluded from most clinical trials for ethical reasons, there is limited information about many medication exposures during pregnancy. This gap in knowledge has led to uncertainty about how to best manage various conditions when women are pregnant. However, researchers are now developing new approaches to study drug exposures during pregnancy more safely and effectively, which will help healthcare providers make better-informed decisions in the future.^[11]

Current research efforts focus on understanding exactly how various substances affect fetal development at different stages of pregnancy. Scientists are working to identify critical periods when the developing baby is most vulnerable to specific exposures, establish more precise dose-response relationships (how different amounts of exposure affect outcomes), and develop methods to predict which babies might be at higher risk for problems. These studies use a combination of animal models, analysis of human data from pregnancy registries, and advanced laboratory techniques that don’t involve direct testing on pregnant women.^[11]

One important area of investigation involves finding ways to measure fetal drug exposure more accurately. Researchers are exploring new methods to estimate how much of a medication actually reaches the baby based on the mother’s dose, how the placenta processes different substances, and how the baby’s developing body handles medications. This information could eventually allow healthcare providers to adjust medication doses during pregnancy to maintain therapeutic benefits for the mother while minimizing exposure to the baby.^[11]

Another research focus is developing interventions that might protect the fetus when exposure to harmful substances is medically necessary or has already occurred. For example, scientists are investigating whether certain nutritional supplements or medications might reduce damage from specific exposures. However, these approaches are still in early research phases, and no proven treatments currently exist to reverse or prevent damage once harmful exposure has occurred during pregnancy.

Long-term follow-up studies are crucial for understanding the full impact of fetal exposures. Some effects may not become apparent until children reach school age or even later in life. Ongoing research tracks children who were exposed to various substances before birth to assess whether they have increased risks of learning disabilities, mental health disorders, or other developmental challenges. This information helps healthcare providers better counsel pregnant women about potential long-term implications of exposures that occur during pregnancy.^[19]

Researchers are also working to better understand how maternal nutrition and other protective factors might modify the effects of harmful exposures. For instance, studies suggest that good nutrition during pregnancy—particularly adequate calcium, iron, and vitamin C—may help reduce lead absorption and limit damage from certain exposures. Understanding these protective mechanisms could lead to practical interventions that improve outcomes even when some exposure has occurred.^[23]

Most common preventive and management methods

• Alcohol avoidance
  • Complete abstinence from all alcoholic beverages (wine, beer, liquor, hard cider) throughout pregnancy
  • Immediate cessation of drinking upon learning of pregnancy
  • Substance abuse treatment and support services for women who struggle to stop drinking
  • Early intervention services and behavioral therapy for children diagnosed with fetal alcohol spectrum disorders
• Prenatal vitamin supplementation
  • Daily folic acid (400-800 micrograms) starting at least one month before pregnancy and continuing throughout pregnancy to prevent neural tube defects
  • Prenatal multivitamins containing iron, calcium, and vitamins A, C, and D
  • Adequate calcium intake to prevent lead absorption from bones
• Medication management
  • Preconception counseling to review all medications and adjust to pregnancy-safe alternatives when possible
  • Risk-benefit analysis by healthcare providers for necessary medications during pregnancy
  • Careful monitoring and dose adjustments of essential medications for chronic conditions
  • Avoidance of teratogenic medications including certain antiepileptic drugs, antimicrobials, anticoagulants, antithyroid medications, and high-dose vitamin A
• Radiation exposure minimization
  • Use of ultrasound as the preferred imaging method during pregnancy when it provides adequate diagnostic information
  • ALARA principle (as low as reasonably achievable) for necessary medical imaging using ionizing radiation
  • Shielding of abdomen and pelvis during X-rays or CT scans when possible
  • Consultation with dosimetry specialists when multiple imaging procedures are needed
  • Careful timing of imaging procedures to avoid the most vulnerable periods of fetal development when medically feasible
• Screening and early intervention
  • Preconception visits to identify risk factors before pregnancy begins
  • Regular prenatal check-ups to monitor fetal development and maternal health
  • Blood lead testing for women at risk of lead exposure
  • Early diagnosis of fetal alcohol spectrum disorders in children to provide intervention services
  • Developmental monitoring and support services for children exposed to harmful substances before birth
• Lifestyle modifications
  • Smoking cessation programs for pregnant women
  • Avoidance of recreational drugs including cocaine, methamphetamines, heroin, and marijuana
  • Lead hazard reduction in pre-1978 homes through proper renovation practices
  • Use of cold tap water for drinking and cooking to minimize lead exposure from pipes
  • Good nutrition with foods high in calcium, iron, and vitamin C to reduce absorption of harmful substances