During pregnancy, women may need to take medications to treat new or existing health conditions. Also, certain vitamins are recommended during pregnancy. Before taking any medication (including over-the-counter medications) or dietary supplement Overview of Dietary Supplements Dietary supplements are used by about 75% of Americans. They are the most common therapies included among integrative medicine and health (IMH) and complementary and alternative medicine (CAM)... read more (including medicinal herbs), a pregnant woman should consult a doctor. Women currently taking medications and planning to become pregnant should consult a doctor before pregnancy, if possible, to see if those medications need to be stopped or changed. (See also the Centers for Disease Control and Prevention: Medicine and Pregnancy.)
Medications or other substances taken by a pregnant woman may reach the fetus by crossing the placenta, the same route taken by oxygen and nutrients, which are needed for the fetus's growth and development. However, those that do not cross the placenta may still harm the fetus by affecting the uterus or the placenta.
Medications or other substances that a pregnant woman takes during pregnancy can affect the fetus in several ways:
No impact on the fetus and its development
Act directly on the fetus, causing damage, abnormal development (leading to birth defects Overview of Birth Defects Birth defects, also called congenital anomalies, are physical abnormalities that occur before a baby is born. They are usually obvious within the first year of life. The cause of many birth... read more ), or death
Alter the function of the placenta, usually by causing blood vessels to narrow (constrict) and thus reducing the supply of oxygen and nutrients to the fetus from the mother (sometimes resulting in the baby being underweight and underdeveloped)
Cause the muscles of the uterus to contract forcefully, indirectly injuring the fetus by reducing its blood supply or triggering preterm labor Preterm Labor Labor that occurs before 37 weeks of pregnancy is considered preterm. Babies born prematurely can have serious health problems. The diagnosis of preterm labor is usually obvious. Measures such... read more and delivery
Affect the fetus indirectly (for example, medications that lower the mother's blood pressure may reduce blood flow to the placenta and thus reduce the supply of oxygen and nutrients to the fetus)
Some medications stay in the body and can have effects after they are stopped. For example, isotretinoin, a medication used to treat skin disorders, is stored in fat beneath the skin and is released slowly over weeks. Isotretinoin can cause birth defects if a woman becomes pregnant within 2 weeks after the medication is stopped. Therefore, women are advised to wait at least 3 to 4 weeks after the medication is stopped before they become pregnant.
How Medications Cross the Placenta
Some of the fetus's blood vessels are contained in tiny hairlike projections (villi) of the placenta that extend into the wall of the uterus. The mother's blood passes through the space surrounding the villi (intervillous space). Only a thin membrane (placental membrane) separates the mother's blood in the intervillous space from the fetus's blood in the villi. Medications in the mother's blood can cross this membrane into blood vessels in the villi and pass through the umbilical cord to the fetus.
How a medication affects a fetus depends on the
Stage of fetal development
Strength and dose of the medication
Permeability of the placenta (how easily substances pass through it)
Genetic factors Genetic Makeup and Response to Drugs Differences in genetic (inherited) makeup among individuals affect what the body does to a drug and what the drug does to the body. The study of genetic differences in the response to drugs... read more in the pregnant woman, which affects how much of the medication is active and available
Pregnant woman's health (for example, nausea and vomiting may decrease absorption of a medication taken by mouth)
Government agencies that oversee drug safety may classify medications based on current knowledge about safety during pregnancy. In the United States, the US Food and Drug Administration (FDA) provides information about drug safety in pregnancy (see FDA: Medicine and Pregnancy). Knowledge about drug safety in pregnancy is based on research in humans and animals and on side effects that are reported by people who have taken the medication. In general, doctors advise pregnant women about taking a medication based on available research, importance of the medication to the health of the pregnant woman, and whether there are other treatments that have less risk to the pregnant woman or fetus. Medications are given in pregnancy if the benefits outweigh the risks.
Vaccines During Pregnancy
Immunization Overview of Immunization Immunization (vaccination) helps the body defend itself against diseases caused by certain bacteria or viruses. Immunity (the ability of the body to defend itself against diseases caused by... read more is as effective in women who are pregnant as in those who are not. (See also Centers for Disease Control and Prevention (CDC): Pregnancy and Vaccination.)
Vaccines Overview of Immunization Immunization (vaccination) helps the body defend itself against diseases caused by certain bacteria or viruses. Immunity (the ability of the body to defend itself against diseases caused by... read more made with a live virus (such as the rubella vaccine Measles, Mumps, and Rubella Vaccine The measles, mumps, and rubella (MMR) vaccine is a combination vaccine that helps protect against these three serious viral infections. The vaccine contains live but weakened measles, mumps... read more and varicella vaccine Varicella Vaccine The varicella vaccine helps protect against chickenpox (varicella), a very contagious infection caused by the varicella-zoster virus. It causes an itchy rash that looks like small blisters with... read more ) are not given to women who are or might be pregnant.
Other vaccines (such as those for cholera Vaccines Cholera is a serious infection of the intestine that is caused by the gram-negative bacteria Vibrio cholerae and that causes severe diarrhea, which can be fatal without treatment. People... read more , hepatitis A Hepatitis A Vaccine The hepatitis A vaccine helps protect against hepatitis A. Typically, hepatitis A is less serious than hepatitis B. Hepatitis A often causes no symptoms, although it can cause fever, nausea... read more , hepatitis B Hepatitis A Vaccine The hepatitis A vaccine helps protect against hepatitis A. Typically, hepatitis A is less serious than hepatitis B. Hepatitis A often causes no symptoms, although it can cause fever, nausea... read more , plague, rabies Prevention Rabies is a viral infection of the brain that is transmitted by animals and that causes inflammation of the brain and spinal cord. Once the virus reaches the spinal cord and brain, rabies is... read more , and typhoid Vaccination Typhoid fever is caused by certain types of the gram-negative bacteria Salmonella. It typically causes a high fever and abdominal pain. Typhoid fever can be spread by consuming food or... read more ) are given to pregnant women only if they are at substantial risk of developing that particular infection and if the risk of side effects from the vaccine is low.
Some vaccines that are considered safe in pregnant women and are recommended during pregnancy include
Influenza (flu) vaccine Influenza Vaccine The influenza virus vaccine helps protect against influenza. Two types of influenza virus, type A and type B, regularly cause seasonal epidemics of influenza in the United States. There are... read more for all women who will be or are pregnant during the flu season
Tetanus-diphtheria-pertussis (Tdap) vaccine Diphtheria-Tetanus-Pertussis Vaccine The diphtheria, tetanus, and pertussis vaccine is a combination vaccine that protects against these three diseases: Diphtheria usually causes inflammation of the throat and mucous membranes... read more (protects against pertussis Pertussis Pertussis is a highly contagious infection caused by the gram-negative bacteria Bordetella pertussis, which results in fits of coughing that usually end in a prolonged, high-pitched,... read more [whooping cough]) during the third trimester of each pregnancy
COVID-19 vaccination for people who are pregnant, breastfeeding, trying to get pregnant, or might become pregnant in the future
Evidence about the safety and effectiveness of COVID-19 vaccination during pregnancy has been growing. These data suggest that the benefits of receiving a COVID-19 vaccine outweigh any known or potential risks of vaccination during pregnancy. (See also CDC: COVID-19 Vaccines While Pregnant or Breastfeeding.)
In August 2023, the US Food and Drug Administration (FDA) approved use of a respiratory syncytial virus (RSV) Respiratory Syncytial Virus (RSV) Infection and Human Metapneumovirus Infection Respiratory syncytial virus infection and human metapneumovirus infection cause upper and sometimes lower respiratory tract infections. Respiratory syncytial virus is a very common cause of... read more vaccine in pregnant individuals between 32 to 36 weeks of pregnancy, with a warning to avoid use prior to 32 weeks (see FDA Approves First Vaccine for Pregnant Individuals to Prevent RSV in Infants).
Medications Used to Treat Heart and Blood Vessel Disorders During Pregnancy
Medications to lower high blood pressure (antihypertensives Medications High blood pressure (hypertension) is persistently high pressure in the arteries. Often no cause for high blood pressure can be identified, but sometimes it occurs as a result of an underlying... read more ) may be needed by pregnant women who have had high blood pressure before pregnancy or who develop it during pregnancy. Either type of high blood pressure increases the risk of problems for a (such as preeclampsia Preeclampsia and Eclampsia Preeclampsia is new high blood pressure or worsening of existing high blood pressure that is accompanied by excess protein in the urine and that develops after the 20th week of pregnancy. Eclampsia... read more ) and for the fetus (see High Blood Pressure During Pregnancy High Blood Pressure During Pregnancy High blood pressure (hypertension) during pregnancy is classified as one of the following: Chronic hypertension: Blood pressure was high before the pregnancy. Gestational hypertension: Blood... read more ). However, antihypertensives can reduce blood flow to the placenta if they lower blood pressure too rapidly in pregnant women. Pregnant women who have to take these medications are closely monitored.
Several types of antihypertensives, such as angiotensin-converting enzyme (ACE) inhibitors and thiazide diuretics, are usually not given to pregnant women. These medications can cause serious problems in the fetus, such as kidney damage, inadequate growth before birth (growth restriction Small-for-Gestational-Age (SGA) Newborns A newborn who weighs less than 90% of newborns of the same gestational age at birth (below the 10th percentile) is considered small for gestational age. Newborns may be small because their parents... read more ), and birth defects. Spironolactone is also not given to pregnant women. This medication may cause the development of feminine characteristics (feminization) in a male fetus.
Digoxin, used to treat heart failure Heart Failure and some abnormal heart rhythms Overview of Abnormal Heart Rhythms Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more , readily crosses the placenta. But at the usual doses, digoxin typically has little effect on the baby before or after birth.
Antidepressants During Pregnancy
Clinical depression is common during pregnancy and, therefore, antidepressants Medications for depression Depression is a feeling of sadness and/or a decreased interest or pleasure in activities that becomes a disorder when it is intense enough to interfere with functioning. It may follow a recent... read more , particularly certain selective serotonin reuptake inhibitors (SSRIs) such as sertraline, are commonly used during pregnancy. For pregnant women, the benefits of treating depression usually outweigh the risks.
Paroxetine appears to increase the risk of heart birth defects Overview of Heart Defects About one in 100 babies is born with a heart defect. Some are severe, but many are not. Defects may involve abnormal formation of the heart's walls or valves or of the blood vessels that enter... read more . So if a pregnant woman takes paroxetine, echocardiography should be done to evaluate the fetus's heart. However, other SSRIs do not increase this risk.
If a pregnant woman takes antidepressants, the newborn may have withdrawal symptoms (such as irritability and shaking) after delivery. To prevent these symptoms, doctors may gradually reduce the dose of the antidepressant during the third trimester and stop the medication before the baby is born. However, if a woman has significant signs of depression or if symptoms worsen as the dose is reduced, antidepressants should be continued. Depression during pregnancy can lead to postpartum depression Postpartum Depression Postpartum depression is a feeling of extreme sadness and loss of interest in usual activities during the first few weeks or months after delivery. Women who have had depression previously are... read more , which involves a serious change in mood and requires treatment.
Antiviral Medications During Pregnancy
Some antiviral medications (such as zidovudine and ritonavir for HIV infection) have been safely used during pregnancy for many years. However, certain antiviral medications may cause problems in the fetus. For example, some evidence suggests that when some HIV regimens with a combination of antiviral medications are given during the first trimester, the risk of cleft lip and palate Cleft Lip and Cleft Palate A cleft is an opening that can form in the lip (cleft lip), roof of the mouth (cleft palate), or both if the tissue does not join together completely during pregnancy. Cleft lip and cleft palate... read more may be increased.
For a pregnant woman with early mild to moderate COVID-19, her treatment team may discuss the risks and benefits and decide whether either nirmatrelvir-ritonavir or remdesivir is appropriate. For pregnant patients hospitalized for COVID-19, use of baricitinib or tocilizumab, may also be considered. Generally, experts recommend that theoretical concerns about the safety of the antiviral medications during pregnancy should not prevent their use in pregnant women.
If a pregnant woman gets influenza, she should seek treatment as soon as possible because treating influenza within 48 hours of when symptoms begin is most effective. However, treatment at any point during the infection reduces the risk of severe complications. No well-designed studies of zanamivir and oseltamivir have been done in pregnant women. However, many studies based on observation indicate that treating pregnant women with zanamivir or oseltamivir does not increase the risk of harmful effects. There is little or no information about the use of other influenza medications during pregnancy.
Acyclovir taken by mouth or applied to the skin, usually to treat herpes simplex virus, appears to be safe during pregnancy.
Medications Used During Labor and Delivery
Medications used to relieve pain during pregnancy Pain relief Labor is a series of rhythmic, progressive contractions of the uterus that gradually move the fetus through the lower part of the uterus (cervix) and birth canal (vagina) to the outside world... read more (such as local anesthetics and opioids) usually cross the placenta and can affect the newborn. For example, they can weaken the newborn's urge to breathe. Therefore, if these medications are needed during labor, they are given in the smallest effective doses.