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Medicine and Drug Use During Pregnancy


The Manual's Editorial Staff

Reviewed/Revised May 2023
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More than half of pregnant women take medicines, drink alcohol, smoke, or use illicit drugs at some time during pregnancy.

How do drugs affect pregnancy?

Many medicines and drugs taken by pregnant women are carried to the baby in the womb by crossing the placenta. The placenta is an organ on the inside of the uterus (womb) that carries blood with oxygen and nutrition to the baby. Certain medicines and drugs can:

  • Cause the baby's organs to grow abnormally, leading to birth defects or death

  • Affect the placenta so it doesn’t work properly

  • Cause the baby to be born too early

How do I know if a medicine is safe to take during pregnancy?

Many medicines and vaccines (shots) aren't safe for pregnant women.

On the other hand, there are some medicines and vaccines that are important to take during pregnancy. They prevent health problems that can harm you or your baby. You shouldn't just stop taking these medicines when you get pregnant. You may need to take medicine during pregnancy if you have a disease that can hurt you or your baby, such as:

Talk to your doctor about the medicines you take:

  • As soon as you know you're pregnant, tell your doctor

  • Ask your doctor about the risks and benefits of your prescription medicines so you can decide whether to continue them or stop them

  • Tell your doctor about any vitamins, supplements, and non-prescription (over-the-counter) medicine you take and ask about their risks

If a medicine you take is risky, doctors can often replace it with a safer medicine. And sometimes even a dangerous medicine is worth taking to treat an even more dangerous illness. For example, you may need to take a medicine called a blood thinner to prevent fatal blood clots. Your doctor will choose the right medicine to keep you and your baby healthy. Always talk with your doctor before stopping, starting, or changing your medicines.


During pregnancy and the first few months of life, your baby is protected against many infections from your immune system Overview of the Immune System The immune system is your body's defense system. It helps protect you from illness and infection. The immune system's job is to attack things that don’t belong in your body, including: Germs... read more . This protection comes to your baby through your bloodstream and across the placenta during pregnancy. If you haven't had all your vaccinations, some are safe to get during pregnancy. However, some vaccines shouldn't be given and some are given only when you have a high risk of infection.

Your doctor will recommend vaccines that are safe to give during your pregnancy:

Vaccines that aren't safe during pregnancy include:

What problems do drugs cause during pregnancy?

Some drugs that can cause problems include:

  • Alcohol

  • Caffeine

  • Cigarettes (tobacco)

  • Marijuana (legal in some states)


Alcohol is a leading cause of birth defects. It can cause:

  • Fetal alcohol syndrome

  • Miscarriage

  • Low birth weight

  • Behavior problems in childhood

Fetal alcohol syndrome is a set of problems that includes abnormal development of the baby's head and face, brain damage, low intelligence, stunted growth, and other problems. As few as 3 alcoholic drinks a day can cause fetal alcohol syndrome.

You shouldn't drink alcohol while pregnant.


Doctors are unclear if caffeine during pregnancy harms a baby. Caffeine is in coffee, some teas, some sodas, energy drinks, chocolate, and some drugs.

Doctors think that caffeine is safe in small amounts, such as one cup of coffee per day.

However, drinking more than 7 cups of coffee per day may cause:

  • Miscarriage or stillbirth

  • Premature birth (a baby that is born too early)

  • Low birth weight

Doctors suggest drinking very little caffeine during pregnancy. You can try decaffeinated drinks instead.


If you smoke cigarettes when pregnant or even breathe in smoke from people who are smoking, it can hurt your baby. It may cause:

  • Low birth weight

  • Birth defects of a baby’s heart, brain, and face

  • Miscarriage

  • Premature birth (a baby that is born too early)

  • Problems with a child’s growth, behavior, and intelligence

You shouldn't smoke at all while pregnant and should avoid being around smoke as much as you can.


Doctors are unclear if marijuana during pregnancy harms a baby but suggest that you avoid it. Marijuana may cause behavior problems in your baby if you use it heavily while pregnant.


Aspartame is an artificial sweetener in some food and drinks and small amounts may be safe during pregnancy. For example, pregnant women should drink less than 1 liter (about 3 cans) of diet soda per day.

What problems do illicit drugs cause during pregnancy?

Using illicit drugs during pregnancy can cause serious problems for a pregnant woman and her baby. All illicit drugs and some medicines (particularly opioids such as oxycodone), when used too much, increase the chances of a baby being too small or being born too early.

Illicit drugs that can cause problems include:

  • Amphetamines

  • Bath salts

  • Cocaine

  • Hallucinogens

  • Opioids


Amphetamines during pregnancy may cause:

  • Birth defects, especially of the heart

  • Problems with a baby’s growth before birth

Bath salts

Bath salts is the name given to a group of drugs made from different chemicals that give the same high as amphetamines. Using bath salts during pregnancy may cause:

  • The baby not to get enough oxygen

  • Stillbirth (death of a baby before or during birth)

  • Placenta problems

  • Birth defects


Using cocaine during pregnancy can narrow blood vessels in the placenta, which can cause:

  • Miscarriage

  • Premature birth (a baby that is born too early)

  • Low birth weight

Women who use cocaine during pregnancy often do other things that can harm their babies, such as smoking, using other drugs, or getting poor medical care. Because of this, doctors aren't sure which problems are caused by the cocaine alone. Still, you shouldn't use cocaine at all while pregnant.


Hallucinogens include Ecstasy (MDMA), methamphetamine, and LSD. Using hallucinogens during pregnancy may cause:

  • Miscarriage

  • Premature birth (a baby that is born too early)

  • Withdrawal symptoms in a baby


Opioids include medicines (such as oxycodone, methadone, and morphine) that doctors prescribe to relieve pain. Heroin is an illicit opioid that people become addicted to and isn't prescribed by doctors. Using any opioids for a long time during pregnancy may cause:

  • Withdrawal symptoms in a baby

  • Miscarriage

  • Premature birth (a baby that is born too early)

  • Low birth weight

If you have a severe, painful injury (such as a broken bone or a bad burn), it's probably safe for your doctor to prescribe an opioid for several days. Otherwise, you should avoid using opioids.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Cafcit, NoDoz, Stay Awake, Vivarin
Dazidox , Endocodone , ETH-Oxydose, Oxaydo, OXECTA, OxyContin, Oxydose , OxyFast, OxyIR, Percolone, Roxicodone, Roxybond, XTAMPZA
Dolophine, Methadose
ARYMO ER, Astramorph PF, Avinza, DepoDur, Duramorph PF, Infumorph, Kadian, MITIGO, MORPHABOND, MS Contin, MSIR, Opium Tincture, Oramorph SR, RMS, Roxanol, Roxanol-T
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