Teratogenic medications and pregnancy planning: what you need to stop before conception and why
Preparing for pregnancy involves more than medical check-ups and taking vitamins. It also includes reviewing your current medications.
Some medications have teratogenic effects, meaning they can interfere with embryonic development and cause congenital birth defects, particularly when exposure occurs during the early stages of pregnancy.
Because organ development takes place during the first weeks after conception—often before pregnancy is even confirmed—medication review and adjustment should be done in advance.
What is a teratogenic effect?
Teratogenic factors are substances or medications that can cause:
congenital birth defects;
abnormal development of organs and body systems;
fetal growth restriction;
an increased risk of pregnancy loss.
The most critical period of exposure is the first 4–10 weeks of gestation.
Medications that should always be reviewed before pregnancy planning
1. Systemic retinoids (isotretinoin and related medications)
These medications are used to treat severe acne.
They are among the best-known teratogenic drugs.
They are associated with a high risk of serious birth defects affecting the central nervous system, heart, and facial structures.
They must be discontinued well before conception, taking into account the time required for the medication to be eliminated from the body.
2. Coumarin anticoagulants (warfarin)
Warfarin crosses the placenta and may cause characteristic embryopathy, including abnormalities of bone and facial development.
Before pregnancy, patients should be switched to an alternative anticoagulation regimen under medical supervision.
3. Certain antiepileptic medications
The best-documented risk is associated with valproic acid.
It may increase the risk of neural tube defects and other congenital malformations.
In some cases, alternative treatment can be selected before pregnancy.
4. Methotrexate
Methotrexate is used to treat autoimmune diseases and certain gynecological conditions.
It is absolutely contraindicated during pregnancy.
It has a strong teratogenic effect, even at low doses.
The medication should be discontinued well in advance, allowing sufficient time for complete elimination from the body.
5. Certain antiandrogen medications
These drugs are used to treat acne and hyperandrogenic conditions.
They should be discontinued before pregnancy planning and replaced with safer alternatives whenever appropriate.
Important to know
Not all medications need to be discontinued before pregnancy.
On the contrary, for women with chronic conditions such as hypertension, diabetes, or thyroid disease, it is often important not to stop treatment on your own, but instead to switch to medications that are considered safe during pregnancy.
Stopping prescribed medication without medical advice may be more dangerous than continuing treatment under a doctor's supervision.
When should you start preparing?
The optimal time to begin preparing for pregnancy is 3–6 months before conception.
During this period, it is possible to:
review your current medications;
replace potentially teratogenic drugs if necessary;
stabilize chronic medical conditions;
reduce the risk of early embryonic exposure to harmful medications.
Why is it important to act in advance?
The embryo is most vulnerable during the first weeks of pregnancy, when many women do not yet know they are pregnant.
For this reason, medication adjustments should be made before conception, not after pregnancy has been confirmed.
Key takeaway
Pregnancy planning is not only about improving overall health—it is also about ensuring that all medications you take are safe for pregnancy.
The goal is not to discontinue as many medications as possible, but to develop a treatment plan that both protects the mother's health and provides the greatest possible safety for the developing baby.