During pregnancy, some medications are safe and some are not.

Some require a higher than usual dose, and some doses change with the advancing pregnancy.

Physicians responsible for providing care to pregnant women are aware of these different medications and their restrictions.

The U.S. Food and Drug Administration has generated a grading system for medications used during pregnancy. The categories are A, B, C, D, and X. The significance of these categories is:

	Definitions	Clinical Application
A	“Controlled studies in women fail to demonstrate a risk to the fetus in the first trimester (and there is no evidence of a risk in later trimester), and the possibility of fetal harm appears remote.”	For all practical purposes, there are almost no Category A drugs.
B	“Either animal-reproduction studies have not demonstrated a fetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the first trimester (and there is no evidence of a risk in later trimesters).”	Category B drugs include prenatal vitamins, acetaminophen and several other medications used routinely and safely during pregnancy. If there is a clinical need for a Category B drug, it is considered safe to use it.
C	“Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.”	Category C drugs have not been shown to be harmful to fetuses (if they had been, they wouldn’t be Category C drugs). However, there are some reasons to be more concerned about these drugs than Category B drugs. If the pregnant patient will benefit from a Category C drug, it is generally used, although most obstetricians would prefer a Category B drug if it will give equivalently good results.
D	“There is positive evidence of human fetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective.)”	Category D drugs have some significant risks. They should be used during pregnancy only when the alternatives are worse.
X	“Studies in animals or human beings have demonstrated fetal abnormalities or there is evidence of fetal risk based on human experience or both, and the risk of the use of the drug in pregnant women clearly outweighs any possible benefit. The drug is contraindicated in women who are or may become pregnant.”	Category X drugs should not be used during pregnancy.

 

Many medications are available without prescription and are considered safe enough for short-term use within published dosage guidelines. Some general rules for medication use during pregnancy are these:

• Acetaminophen is considered safe
• Pseudoephedrine is considered safe
• Guaifenesin is considered safe
• Diphenhydramine is considered safe
• Local anesthetics (Xylocaine) may be used with safety, although the addition of epinephrine to them is problematic. Epinephrine may have unpredictable effects on the maternal cardiovascular system (and hence the blood flow to the baby), so epinephrine is generally to be avoided.
• Aspirin is not considered totally safe, and should only be used under the guidance of a qualified healthcare professional. In limited circumstances, it may be beneficial for a pregnancy in ways that outweigh the risks.
• Codeine, Demerol, Morphine and other narcotics may be used as needed at any stage of pregnancy, but the addictive potential should be recognized. Other than the risk of fetal drug withdrawal syndrome, these major pain relievers are considered safe enough for use during pregnancy.
• Penicillins are safe
• Cephalosporins are safe
• Erythromycin is safe
• Azithromycin is safe
• Metronidazole is safe after 14 weeks gestation. Safety prior to 14 weeks hasn’t been established.
• Tetracyclines are considered unsafe at any time during pregnancy
• Aminoglycosides are basically safe during pregnancy, but renal and ototoxicity are potential problems if the dose is high or prolonged.
• Clindamycin is safe
• Chloramphenicol is probably safe prior to 28 weeks
• Sulfa drugs are safe prior to 34 weeks. After that, babies may develop jaundice if exposed to sulfa.
• Quinine is only to be used in life-threatening, chloroquine-resistant P. Falciparum infections
• Miconazole is safe
• Clotrimazole is safe
• Quinacrine is probably safe during pregnancy
• Chloroquine may cause congenital defects with prolonged or high doses
• Pyrimethamine is safe after 1st trimester. Add folic acid supplement.
• Trimethoprim is safe after 1st trimester. Add folic acid supplement.
• Primaquine may cause hemolytic anemia in the presence of G6PD deficiency. You may use it if needed.