Which Medicine Should I Avoid During Pregnancy?

Which Medicines Should I Avoid During Pregnancy? A Comprehensive Guide

Pregnancy is a transformative period in a woman’s life, marked by joy and excitement but also by heightened caution regarding health and wellness. One of the most critical concerns for expectant mothers is the safety of medications. The choices a woman makes about what she ingests—whether it's food, drink, or medicine—can directly impact the developing baby. During pregnancy, medications can cross the placenta, potentially affecting foetal development. Thus, it’s essential to know which medicines to avoid, which ones may be safe, and how to navigate health challenges while pregnant.
In this guide, we will explore in-depth which medicines should be avoided during pregnancy, why certain drugs pose risks, and how to make safe choices in consultation with healthcare providers.

The Importance of Medication Safety in Pregnancy

The safety of medications during pregnancy is a critical concern due to the potential risks of teratogenic effects—birth defects caused by exposure to harmful substances. Some medicines can interfere with foetal development, leading to congenital disabilities, developmental delays, or other serious complications. In other cases, medications might increase the risk of miscarriage, premature birth, or stillbirth.
During the first trimester, the risk of harmful effects is particularly high, as the organs of the foetus are forming. However, risks remain throughout the pregnancy, as exposure to certain substances can impact the baby’s growth and the mother’s health. It is crucial for pregnant women to only take medications that are essential for their health and have been evaluated for safety.

Categories of medication safety during pregnancy

The U.S. Food and Drug Administration (FDA) has established a system that categorises medications based on their potential risks to pregnancy. These categories—A, B, C, D, and X—are determined by evaluating available data from human and animal studies.

Category A: Controlled studies in humans have shown no risk to the fetus. These medications are generally considered safe during pregnancy.

Category B: Animal studies have not shown a risk to the foetus, but there are no well-controlled studies in humans, or animal studies have shown an adverse effect that wasn’t confirmed in humans.

Category C: Animal studies have shown adverse effects on the foetus, but there are no well-controlled human studies. These medications should be given only if the potential benefits justify the risks.
Category D: There is evidence of human foetal risk, but the potential benefits from the use of the drug in pregnant women may be acceptable despite the risks (e.g., in life-threatening situations).
Category X: Studies in animals or humans have demonstrated foetal abnormalities, or there is evidence of foetal risk. The risks of using these drugs outweigh any potential benefits. These medications should never be used during pregnancy.

Medicines to Avoid During Pregnancy

Here’s a detailed look at medicines that should be avoided or used with extreme caution during pregnancy:

1. Non-steroidal anti-inflammatory drugs (NSAIDs)

Examples: Ibuprofen (Advil, Motrin), Naproxen (Aleve)

Risks: NSAIDs are commonly used to treat pain, inflammation, and fever, but they can pose significant risks during pregnancy. Taking NSAIDs in the third trimester can increase the risk of premature closure of the foetal ductus arteriosus, a vital blood vessel in the etus. This can lead to complications like pulmonary hypertension. They may also contribute to low amniotic fluid levels and miscarriage when taken in early pregnancy.

2. Aspirin

Examples: Aspirin (Bayer, Ecotrin)

Risks: High-dose aspirin should be avoided during pregnancy, especially during the third trimester. It can cause complications such as bleeding, prolonged labour, and issues with the baby’s heart. Low-dose aspirin may be recommended in certain cases, such as for women at risk of preeclampsia, but this should only be taken under the guidance of a healthcare provider.

3. Isotretinoin (Accutane)

Uses: Treats severe acne.

Risks: Isotretinoin is a well-known teratogen that can cause severe birth defects, including malformations of the heart, brain, and face. Women of childbearing age should not use isotretinoin unless they are on an approved pregnancy prevention program. It is classified as Category X, meaning it is completely contraindicated during pregnancy.

4. ACE Inhibitors

Examples: Enalapril (Vasotec), Lisinopril (Prinivil, Zestril)

Risks: ACE inhibitors, which are used to treat high blood pressure, can cause serious damage to the developing kidneys of the foetus, particularly if taken during the second and third trimesters. They can also lead to low amniotic fluid levels and delayed foetal growth.

5. Angiotensin II Receptor Blockers (ARBs)

Examples: Losartan (Cozaar), Valsartan (Diovan).

Risks: Like ACE inhibitors, ARBs can cause foetal kidney damage and low amniotic fluid levels. They are generally avoided during pregnancy due to the risk of congenital defects.

6. Warfarin (Coumadin)

Uses: Blood thinner is used to prevent blood clots.

Risks: Warfarin is classified as Category X during pregnancy because it can cross the placenta and cause foetal bleeding, leading to birth defects and miscarriage. In some cases, heparin or low-molecular-weight heparin (LMWH) is used as a safer alternative during pregnancy.

7. Certain antibiotics

Tetracyclines (Doxycycline, Minocycline): These antibiotics can cause discolouration of the baby’s teeth and affect bone growth. They are especially harmful when used after the fourth month of pregnancy.

Fluoroquinolones (ciprofloxacin, levofloxacin): These are generally avoided during pregnancy due to concerns about potential damage to developing cartilage and joints in the foetus.

Sulfonamides (Bactrim, Septra): These can increase the risk of jaundice and other health issues, particularly in the third trimester.

8. Anti-seizure medications

Examples: valproic acid (Depakote), phenol (Dilantin), carbamazepine (Tegretol).

Risks: Many anti-seizure medications are known teratogens that can cause congenital malformations such as neural tube defects, cleft palate, and heart problems. Valproic acid, in particular, is associated with a high risk of birth defects and developmental disorders. It should be avoided unless absolutely necessary for the mother’s health.

9. Thalidomide

Uses: Historically used to treat morning sickness, now used for leprosy and some cancers.

Risks: Thalidomide is infamous for causing severe limb malformations and other birth defects when taken during pregnancy. Even though it is no longer used to treat morning sickness, its use in certain medical conditions requires strict regulation, including pregnancy prevention programs.

10. Methotrexate

Uses: Treats certain cancers, autoimmune diseases, and ectopic pregnancy.

Risks: Methotrexate is a folic acid antagonist that can disrupt cell division and DNA synthesis. It is highly teratogenic and can cause miscarriage, foetal growth restriction, and severe birth defects. It is classified as Category X and should never be used during pregnancy except in cases of ectopic pregnancy management.

11. Statins

Examples: atorvastatin (Lipitor), simvastatin (Zocor)

Risks: Statins, which are used to lower cholesterol levels, can interfere with foetal development, particularly in the first trimester. They are generally avoided during pregnancy, as their benefits do not outweigh the potential risks.

12. Chemotherapy Drugs

Examples: cyclophosphamide, methotrexate

Risks: Many chemotherapy drugs are known to be teratogenic, especially during the first trimester when the foetus is most vulnerable to external influences. These drugs can cause birth defects, miscarriage, and developmental delays. However, in cases of cancer during pregnancy, some chemotherapy agents may be used with extreme caution, usually in the second and third trimesters.

Herbal Medicines and Supplements to Avoid

In addition to prescription and over-the-counter medications, certain herbal medicines and supplements should also be avoided during pregnancy. While some may be natural, they are not necessarily safe for pregnant women or their babies.

1. St. John’s Wort

Uses: Commonly used to treat depression.

Risks: St. John’s Wort can interfere with medications and may increase the risk of miscarriage and preterm labour.

2. Ginkgo Biloba

Uses: Improves cognitive function and memory.

Risks: Ginkgo biloba may increase the risk of bleeding and has been linked to potential complications during pregnancy.

3. Saw Palmetto

Uses: Commonly used to treat symptoms of enlarged prostate and hormone imbalances.

Risks: Saw palmetto has hormonal effects that may be harmful to the foetus, particularly in the early stages of pregnancy.

4. Dong Quai

Uses: Used in traditional Chinese medicine to improve circulation and treat menstrual disorders.

Risks: Dong quai is associated with an increased risk of miscarriage due to its blood-thinning properties.

5. Black Cohosh

Uses: Used to induce labour and treat menopausal symptoms.

Risks: Black cohosh may stimulate uterine contractions and increase the risk of preterm labour or miscarriage.

Managing health conditions during pregnancy

If you are pregnant and dealing with chronic health conditions like diabetes, hypertension, or epilepsy, it’s important to work closely with your healthcare provider to manage your condition while minimising risks to your baby. Here are some common strategies:

Diabetes: Insulin is considered safe for use during pregnancy. Some oral antidiabetic medications, like metformin, may also be used under careful supervision.

Hypertension: Beta-blockers like labetalol and calcium channel blockers like nifedipine may be prescribed as safer alternatives to ACE inhibitors and ARBs during pregnancy.

Epilepsy: Certain anti-seizure medications like lamotrigine and levetiracetam may be considered safer options, though risks must always be carefully weighed.

General Tips for Safe Medication Use During Pregnancy

Consult your doctor before taking any medication. Even over-the-counter drugs and supplements should be discussed with your healthcare provider.

Avoid Self-Medication: Never assume a drug is safe just because it doesn’t require a prescription. Many over-the-counter medications pose risks during pregnancy.

Read labels and instructions. Carefully: Always check for warnings related to pregnancy on medication packaging.

Use the Lowest Effective Dose: If a medication is deemed necessary, use the smallest dose for the shortest time possible.

Regularly Monitor Your Condition: If you are managing a chronic illness, work with your doctor to adjust medications as needed and to monitor both your health and the baby’s development.

Conclusion

The health of both the mother and the developing baby is a delicate balance that requires careful consideration when it comes to medication. While some drugs are essential to managing pre-existing conditions or new health issues that arise during pregnancy, many are unsafe due to the risks of birth defects, miscarriage, or other complications. Always consult your healthcare provider before starting, stopping, or continuing any medication during pregnancy. With the right guidance, expectant mothers can make informed decisions to protect their health and the health of their baby.