Medication Use During Pregnancy

A common concern in pregnancy is the use of medications which can be obtained without a prescription. The term used for them is “over-the-counter” (OTC). In some countries virtually all medications can be purchased without a prescription. For simplicity and clarity in this article, I’ll use “OTC” to refer to the medications discussed, available without a prescription in any setting.

About 80% of women use medication(s) during pregnancy. Most OTC medications have a good safety profile, others are proved unsafe, or are known to harm the baby. Ten percent of birth defects are attributed to medications used in pregnancy.

In 1975, the U.S. Food and Drug Administration (FDA) developed a scale, categories A through D, to assign each drug a category in accordance with its degree of risk to the baby when the drugs are used in pregnancy. That information is available and applies to women everywhere. Many drugs have not been studied in pregnancy. Some drugs have different effects at different stages of pregnancy.

Category A: Controlled studies in women have failed to demonstrate a risk to the baby throughout the pregnancy. The possibility of fetal harm appears remote.

Category B: Either animal studies have not demonstrated a fetal risk, but there are no controlled studies in women, or animal reproduction studies have shown an adverse effect that was not confirmed in women in the first trimester (and there is no evidence of risk in later trimesters).

Category C: Either animal studies have revealed adverse effects on the fetus and there are no controlled studies in women, or studies in women and animals are not available. Potential benefit may justify risk.

Category D: There is positive evidence of human fetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (i.e. life-threatening situations.)

Pain medications. The most common medications for pain are aspirin, paracetamol (Panadol), acetaminophen (Tylenol), and ibuprofen (Advil, Motrin). Acetaminophen/Paracetamol, the preferred pain medication throughout the pregnancy, is in Category B.  Aspirin is in Category D throughout the pregnancy. Ibuprofen is in Category B during the first two trimesters, but Category D in the third trimester.

Cold medications. Decongestants, expectorants, and antihistamines are commonly used by pregnant women. Like other OTC medications, they have not been studied well in pregnancy. For that reason many physicians are reluctant to recommend any treatment for the common cold.

Pseudoephedrine is the decongestant of choice in pregnancy, assigned to Category B. It has the potential to elevate blood pressure, and potentially adversely affect blood flow to the baby.

Chlorpheniramine is the antihistamine of choice in pregnancy, assigned to Category B.

Diphenhydramine, an antihistamine, is also widely used in pregnancy as a sedative and an anti-nausea drug, although few data confirm its safety during pregnancy. Also, adverse drug interactions that do not occur in non-pregnant patients may occur in pregnant patients. It is assigned to Category B.

Dextromethorphan is the most commonly used cough suppressant. It has been associated with birth defects in chicken embryos, but it does not show an increase rate of defects in humans Dextromethorphan is assigned to Category C by the FDA.

Guifenesin, the most commonly used expectorant, has been associated with an increased risk of brain and spinal nerve defects when used in the first trimester of pregnancy in the presence of fever. It is assigned to Category C.

Antacid preparations. Several antacids are available OTC, containing various active ingredients, including aluminum, magnesium and calcium. All are generally regarded safe in pregnancy, although there are sporadic reports of birth defects with prolonged use of high-dose aluminum-containing preparations.

Maalox, an antacid containing aluminum and magnesium is generally regarded as safe, and is assigned to Category B.

Tums, which are calcium carbonate, are generally regarded as safe, but is assigned to Category C.

Mylanta Gas, with simethicone, is an anti-flatulant, generally regarded as safe in pregnancy, but also is assigned to Category C.

Smoking deterrents. Researchers believe that nicotine is harmful to the developing baby, because smoking is known to cause harmful fetal effects, including intrauterine growth retardation (the baby is growing slower than normal), premature birth, spontaneous abortion (miscarriage), and an increased risk of sudden infant death syndrome. The FDA classifies nicotine as a Category D drug. Nicotine replacement products in pregnancy have not been adequately studied. Smoking, however, is likely to be more harmful to the baby than nicotine replacement products, particularly because smoke contains more than 3,000 different chemicals that can potentially cause harm to humans. One of the main components of cigarette smoke is carbon monoxide, a known toxin to the developing baby.

These facts about medications in pregnancy are not intended to encourage pregnant women to self-treat, but for understanding on this issue. The use of any medications, herbs, and dietary supplements should be discussed with your doctor or healthcare provider, before starting, stopping, or sporadic intake of any of these substances.

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