What medications have absolute contraindications in pregnancy?

Medications with Absolute Contraindications in Pregnancy

The following medications are absolutely contraindicated in pregnancy and must be avoided in women who are or may become pregnant: warfarin, isotretinoin, sodium valproate, ACE inhibitors (second/third trimester), angiotensin receptor blockers (ARBs), statins, and all weight-loss medications. 1, 2, 3, 4

Category X Medications (Absolutely Contraindicated)

Teratogenic Agents

• Warfarin is absolutely contraindicated throughout pregnancy due to its association with fetal malformations and must not be taken during pregnancy or by women attempting to conceive 3
• Isotretinoin is Category X and absolutely contraindicated due to severe teratogenic effects 4
• Sodium valproate is a known teratogen causing neural tube defects and major congenital malformations, and is contraindicated in all females of childbearing potential 2

Cardiovascular Medications

• ACE inhibitors (benazepril, captopril, fosinopril, lisinopril, quinapril) are absolutely contraindicated in pregnancy, particularly in the second and third trimesters, causing fetal renal dysplasia, oligohydramnios, pulmonary hypoplasia, and intrauterine growth restriction 1, 2
• Angiotensin receptor blockers (ARBs) (irbesartan, losartan, valsartan, candesartan) are absolutely contraindicated in pregnancy with similar mechanisms of harm as ACE inhibitors 1, 2
• Statins should be avoided in pregnancy and must be stopped at conception in sexually active women of childbearing age not using reliable contraception 1
• Atenolol should never be used in pregnancy due to pronounced fetal growth restriction effects 2

Weight-Loss and Metabolic Medications

• All weight-loss medications are absolutely contraindicated in women who are or may become pregnant, including:
  • Phentermine 1
  • Orlistat 1
  • Lorcaserin 1
  • Phentermine/topiramate 1
  • Naltrexone/bupropion 1
  • Liraglutide 3.0 mg (weight-loss dose) 1

Neuropsychiatric Medications

• Topiramate is contraindicated during pregnancy due to adverse fetal effects including birth defects 1, 2
• Lithium poses significant teratogenic risk and must be stopped immediately, particularly in the first trimester, due to cardiac malformations and other congenital defects 2

Critical Timing Considerations

First Trimester (Weeks 3-8)

• This is the critical period of organogenesis when medications pose the highest risk for structural birth defects 2
• ACE inhibitors should be stopped as soon as possible in the first trimester, though first trimester exposure does not appear associated with congenital malformations after adjusting for confounders 1

Second and Third Trimesters

• ACE inhibitors and ARBs become absolutely contraindicated specifically during these trimesters due to functional abnormalities: fetal renal damage, oligohydramnios, and permanent kidney injury 1, 2

Essential Counseling Points

Contraception Requirements

• Women of childbearing age taking any of these medications must use reliable contraception 1
• All weight-loss medications require counseling regarding reliable contraceptive methods 1
• ACE inhibitors, ARBs, and statins should be stopped at conception in sexually active women not using reliable contraception 1

Common Pitfalls to Avoid

• Do not abruptly discontinue medications for chronic conditions without medical supervision, as uncontrolled maternal disease can harm the fetus more than appropriate medication use 2
• Treatment with a contraindicated medication does not automatically justify termination of pregnancy; individual risk assessment and management strategy are required 5
• The single exception for ACE inhibitors is active scleroderma renal crisis, where maternal benefit may outweigh fetal risk 2