Some Medications and Risk of Problems During Pregnancy*

Examples

Possible Problems

Anti-anxiety medications

Benzodiazepines (such as diazepam, alprazolam, or lorazepam)

When taken late in pregnancy, very slow breathing or a withdrawal syndrome (causing irritability, shaking, and exaggerated reflexes) in the newborn

Antibiotics

Aminoglycosides (such as amikacin, gentamicin, neomycin, streptomycin, and tobramycin)

Damage to the fetus's ear (ototoxicity), resulting in variable deafness

Chloramphenicol

In women or fetuses with G6PD deficiency, the breakdown of red blood cells

Possibly gray baby syndrome (a serious and often fatal disorder)

Fluoroquinolones (such as ciprofloxacin, ofloxacin, levofloxacin, and norfloxacin)

Possibility of bone and joint abnormalities (seen only in animals)

Nitrofurantoin

In women or fetuses with G6PD deficiency, the breakdown of red blood cells

Primaquine

In women or fetuses with G6PD deficiency, the breakdown of red blood cells

Sulfonamides (such as sulfasalazine and trimethoprim- sulfamethoxazole)

When given late in pregnancy, jaundice and, without treatment, brain damage (kernicterus) in the newborn

With sulfasalazine, much less risk of problems

In women or fetuses with G6PD deficiency, the breakdown of red blood cells

Tetracycline

Slowed bone growth, permanent yellowing of the teeth, and increased risk of cavities in the child

Occasionally, liver failure in the pregnant woman

Trimethoprim

Defects of the brain and spinal cord (neural tube defects), such as spina bifida

Anticoagulants

Factor Xa inhibitors such as rivaroxaban, apixaban, or edoxaban

Possible risk of bleeding in the pregnant woman or fetus

Heparin or enoxaparin

Rarely causes thrombocytopenia (a decrease in the number of platelets, which help blood clot) in the pregnant woman, possibly resulting in excessive bleeding

Warfarin

Birth defects including malformed bones, intellectual disability, congenital cataracts, and other problems with the eyes in the fetus

Bleeding problems in the fetus and the pregnant woman

Antidepressants

Bupropion

Possible risk of birth defects in first trimester; likely safe in pregnancy

Citalopram

When taken during the first trimester, increased risk of birth defects (particularly heart defects)

When taken during the third trimester, discontinuation syndrome (which includes dizziness, anxiety, irritability, fatigue, nausea, chills, and muscle aches) and persistent pulmonary hypertension of the newborn (the arteries to the lungs remain narrowed after delivery, limiting blood flow to the lungs and thus the amount of oxygen in the bloodstream)

Escitalopram

When taken during the third trimester, discontinuation syndrome and persistent pulmonary hypertension of the newborn

Fluoxetine

When taken during the third trimester, discontinuation syndrome and persistent pulmonary hypertension of the newborn

Paroxetine

When taken during the first trimester, increased risk of birth defects, particularly heart defects

When taken during the third trimester, discontinuation syndrome and persistent pulmonary hypertension of the newborn

Sertraline

When taken during the third trimester, discontinuation syndrome and persistent pulmonary hypertension of the newborn

Venlafaxine

When taken during the third trimester, discontinuation syndrome

Antiemetic medications (used to relieve nausea)

Doxylamine and pyridoxine (vitamin B6)

No increased risk of birth defects

Metoclopramide

When taken during the third trimester and/or delivery, abnormal muscle movements (extrapyramidal symptoms) or a blood disorder (methemoglobinemia) may potentially occur in the newborn

Meclizine

Birth defects seen only in animals

Ondansetron

No conclusive evidence of birth defects in animals

When taken during the first trimester, possible risk of congenital heart disease

Promethazine

No conclusive evidence of birth defects in animals

Possible risk of bleeding in the newborn

Antifungal medications

Amphotericin B

No increased risk of birth defects, but no well-designed studies done in pregnant women

Fluconazole

No increased risk of birth defects after a single low dose

When high doses are taken for most or all of the first trimester, increased risk of birth defects, such as abnormalities in the heart, face, skull, ribs, and limbs

Miconazole

No increased risk of birth defects when applied to the skin

When taken by mouth, side effects in animal studies

When inserted into the vagina, no increased risk of birth defects

Terconazole

No increased risk of birth defects

When inserted into the vagina, no increased risk of birth defects

Antihistamines

Loratadine

Possibly in male newborns, a birth defect of the urethra in which the opening of the urethra is in the wrong place on the penis (hypospadias); likely safe in pregnancy

Meclizine

Birth defects in rodents but no proof of this effect in humans

Antihypertensive medications

Aldosterone antagonists (medications that block the action of the hormone aldosterone), such as spironolactone and eplerenone

With spironolactone, possible development of feminine characteristics in male fetuses

With eplerenone, no increased risk of birth defects in animals, but no well-designed studies done in pregnant women

Angiotensin-converting enzyme (ACE) inhibitors

When taken late in pregnancy, possible kidney damage in the fetus, a reduction in the amount of fluid around the developing fetus (amniotic fluid), and defects of the face, limbs, and lungs

Beta-blockers

Labetalol is the preferred beta-blocker in pregnancy

When atenolol, propranolol, and some other beta-blockers are taken during pregnancy, a slowed heart rate, a low blood sugar level, and possibly inadequate growth of the fetus (growth restriction) and preterm birth

Low blood pressure in the mother

Calcium channel blockers

Nifedipine and nicardipine are the preferred calcium channel blockers during pregnancy

Thiazide diuretics

A decrease in the levels of oxygen, sodium, and potassium and in the number of platelets in the fetus's blood

Inadequate growth of the fetus

Antipsychotic medications

Aripiprazole

When taken during the third trimester, increased risk of abnormal muscle movements (extrapyramidal symptoms) and/or withdrawal symptoms in newborns following delivery

Haloperidol

Harmful effects in animals

When taken during the first trimester, possible birth defects in the limbs

When taken during the third trimester, increased risk of the following:

  • Repetitive, involuntary movements (extrapyramidal symptoms)

  • Restlessness, irritability, shaking, difficulty breathing, and feeding problems (symptoms of medication withdrawal) in the newborn because at birth, passage of the medication from the mother through the placenta stops

Lurasidone

No evidence of harmful effects in animals

When taken during the third trimester, increased risk of the following:

  • Repetitive, involuntary movements

  • Restlessness, irritability, shaking, difficulty breathing, and feeding problems (symptoms of medication withdrawal) in the newborn because at birth, passage of the medication from the mother through the placenta stops

Olanzapine

Harmful effects in animals

When taken during the third trimester, increased risk of the following:

  • Repetitive, involuntary movements

  • Restlessness, irritability, shaking, difficulty breathing, and feeding problems (symptoms of medication withdrawal) in the newborn because at birth, passage of the medication from the mother through the placenta stops

Antiseizure medications

Carbamazepine

Increased risk of birth defects, including neural tube defects (such as spina bifida)

Bleeding problems in the newborn (hemorrhagic disease of the newborn), which can be prevented if pregnant women take vitamin K by mouth every day for a month before delivery or if the newborn is given an injection of vitamin K soon after birth

Lamotrigine

No substantial increased risk of birth defects

Lacosamide

Additional data regarding effects required

Levetiracetam

Minor bone abnormalities seen in animals

No substantial increased risk in people

Phenobarbital

Increased risk of birth defects, including neural tube defects (such as spina bifida)

Bleeding problems in the newborn

Phenytoin

Increased risk of birth defects (such as cleft lip and heart defects)

Bleeding problems in the newborn

Trimethadione

High risk of birth defects (such as cleft palate and defects of the heart, skull, face, hands, and abdomen)

Risk of a miscarriage

Valproate

Increased risk of birth defects, including cleft palate, neural tube defects (such as a meningomyelocele), and defects of the heart, face, skull, spine, and limbs

Chemotherapy drugs

Actinomycin

Possibility of birth defects (seen only in animals)

Busulfan

Birth defects such as underdevelopment of the lower jaw, cleft palate, abnormal development of the skull bones, spinal defects, ear defects, and clubfoot

Inadequate growth of the fetus (growth restriction)

Chlorambucil

Birth defects such as underdevelopment of the lower jaw, cleft palate, abnormal development of the skull bones, spinal defects, ear defects, and clubfoot

Inadequate growth of the fetus (growth restriction)

Colchicine

Possibility of birth defects (seen in animals)

Abnormalities in sperm in male children

Cyclophosphamide

Birth defects such as underdevelopment of the lower jaw, cleft palate, abnormal development of the skull bones, spinal defects, ear defects, and clubfoot

Inadequate growth of the fetus (growth restriction)

Doxorubicin

Heart problems for the mother, depending on the dose taken

Birth defects

Mercaptopurine

Birth defects such as underdevelopment of the lower jaw, cleft palate, abnormal development of the skull bones, spinal defects, ear defects, and clubfoot

Inadequate growth of the fetus (growth restriction)

Methotrexate

Birth defects such as underdevelopment of the lower jaw, cleft palate, abnormal development of the skull bones, spinal defects, ear defects, and clubfoot

Inadequate growth of the fetus (growth restriction)

Vinblastine

Possibility of birth defects (seen only in animals)

Vincristine

Possibility of birth defects (seen only in animals)

Mood-stabilizing medication

Aripiprazole

When taken during the third trimester, increased risk of abnormal muscle movements (extrapyramidal symptoms) and/or withdrawal symptoms in newborns following delivery

Lithium

When taken during the first trimester, increased risk of birth defects (mainly of the heart)

When taken later in pregnancy, lethargy, reduced muscle tone, poor feeding, underactivity of the thyroid gland, and nephrogenic diabetes insipidus in the newborn

Risperidone

Harmful effects in animals

No evidence of increased risk of birth defects, but no well-designed studies done in pregnant women

When taken during the third trimester, increased risk of the following:

  • Repetitive, involuntary movements

  • Restlessness, irritability, shaking, difficulty breathing, and feeding problems (symptoms of medication withdrawal) in the newborn because at birth, passage of the medication from the mother through the placenta stops

Diabetes (hypoglycemic) medications

Chlorpropamide

Glyburide

Metformin

Tolbutamide

A very low blood sugar level in the newborn

Nonsteroidal anti-inflammatory drugs (NSAIDs)

Aspirin and other salicylates

Ibuprofen

Naproxen

When taken in large doses, possibly miscarriage during the first trimester, a delay in the start of labor, premature closing of the connection between the aorta and artery to the lungs (ductus arteriosus), jaundice, necrotizing enterocolitis (damage to the lining of the intestine), and (occasionally) brain damage in the fetus (kernicterus) and bleeding problems in a woman during and after delivery and/or in the newborn

When taken late in pregnancy, a reduction in the amount of fluid around the developing fetus

When low doses of aspirin are taken, no significant risk of birth defects

Opioids

Buprenorphine

No evidence of increased risk of birth defects but may have other harmful effects on the fetus or newborn

Restlessness, irritability, shaking, difficulty breathing, and feeding problems (symptoms of opioid withdrawal) in the newborn because, at birth, passage of the medication from the mother through the placenta stops

Codeine

Hydrocodone

Hydromorphone

Meperidine

Morphine

Restlessness, irritability, shaking, difficulty breathing, and feeding problems (symptoms of opioid withdrawal) in the newborn, possibly occurring 6 hours to 8 days after birth

If high doses are given in the hour before delivery, possibly drowsiness and a slowed heart rate in the newborn

Methadone

Restlessness, irritability, shaking, difficulty breathing, and feeding problems (symptoms of opioid withdrawal) in the newborn

Sex hormones

Danazol

When taken very early in pregnancy, masculinization of a female fetus’s genitals, sometimes requiring surgery for correction

Hormonal contraceptives (birth control pills, patches, or rings; contraceptive injections or implants; hormonal intrauterine devices [IUDs])

Exposure to estrogen-progestin contraceptives prior to conception or during pregnancy does not appear to be associated with an increased risk of major birth defects

Exposure to medroxyprogesterone acetate does not appear to increase risk of major birth defects

17-hydroxyprogesterone caproate

Safe in second or third trimester of pregnancy

Progesterone (oral or vaginal)

Exposure during pregnancy not associated with increased risk of major birth defects

Skin treatment

Isotretinoin

Birth defects, such as heart defects, small ears, and hydrocephalus (sometimes called water on the brain)

Intellectual disability

Risk of miscarriage

Thyroid medications

Levothyroxine

Preferred treatment of hypothyroidism during pregnancy; safe in pregnancy

Methimazole

An enlarged or underactive thyroid gland in the fetus

Facial and scalp defects in the newborn

Other potential abnormalities

Propylthiouracil

An enlarged or underactive thyroid gland in the fetus

Liver damage in the mother

Radioactive iodine

Destruction of the thyroid gland in the fetus

When given near the end of the first trimester, a very overactive and enlarged thyroid gland in the fetus

Increased risk of childhood cancer

Triiodothyronine

An overactive and enlarged thyroid gland in the fetus

Vaccines

COVID-19 vaccines

No known safety concerns for pregnant people or for their fetuses or newborns

Inactivated influenza vaccine

No safety concerns for pregnant people or for fetuses or newborns

Tetanus, reduced diphtheria toxoid, acellular pertussis (Tdap) vaccine

No safety concerns for pregnant people or for fetuses or newborns

Live-virus vaccines such as those formeasles, mumps, and rubella; chickenpox (varicella); polio; and yellow fever

With rubella and varicella vaccines, potential infection of the placenta and developing fetus

With other live vaccines, potential but unknown risks

Other medications

Corticosteroids

Possibly a cleft lip when taken during the first trimester

Hydroxychloroquine

No increased risks at the doses usually used

Isoniazid

Possible harmful effects on the liver or damage to the peripheral nerves (causing abnormal sensations and/or weakness)

Pseudoephedrine (a decongestant)

Narrowing of the blood vessels in the placenta, possibly reducing the amount of oxygen and nutrients the fetus receives and thus resulting in inadequate growth before birth

Possible risk of a defect in the wall of the abdomen that allows the intestines to protrude outside the body (called gastroschisis)

Vitamin K

In women or fetuses with G6PD deficiency, destruction of red blood cells (hemolysis)

* Women who are pregnant or are planning to become pregnancy should talk with their doctor about the risks and benefits of medications before stopping or starting any medication. Unless medically necessary, medications should not be used during pregnancy. However, some medications are essential to maintain the health of the pregnant woman or the fetus, and women should not stop taking these before consulting their doctor.

† Opioids are used to relieve pain. However, they also cause an exaggerated sense of well-being, and if used too much, they can cause dependence and addiction.

‡ Insulin is usually preferred during pregnancy.

G6PD = glucose-6-phosphate dehydrogenase.