The years during which medications for pregnant women were described as A, B, C, D and X are gone. No longer can anyone rely on the old system which categorized medications alphabetically with A considered safe, B of acceptable risk, and X defined the teratogenic. The A, B, C system was based on what was generally considered a sliding case of safety and increased risk.
In the Compendium of Pharmaceuticals and Specialities, risk factors for drug use during pregnancy used 5 categories.
Category 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 trimesters). And the possibility of fetal harm appears remote.
Category 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 o evidence of a risk in later trimesters).
Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embyocidal 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 justifes the potential risk to the fetus.
Category 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 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.
These categories are now obsolete. New labels are now mandatory. Health care professionals will need to read medication labels much more carefully than before to determine if the medication prescribed warrants the risk in both pregnant and lactating women. The new labels embrace both pregnant and lactating women (the latter having being ignored up to now) and are required to feature the most recent research and are applicable to all women who are pregnant, lactating and/or of reproductive age – yet another distinction hitherto also ignored.
Medications such as ACE inhibitors, anti-convulsants, some antibiotics, anti-depressants, and evencommon treatments such as those for high blood pressure can have a detrimental effect on pregnancy, leading to either miscarriage or birth defects.
The new labels are required to be more current, offering the latest clinical research results. They will include three requirements as related to the drug – pregnancy testing, contraception and effects on fertility. While the labeling changes went into effect in June 2015, only prescription drugs approved after June 30, 2001 will require the new labels by June 2018. OTC medications are not affected by the new rules.
The recommendation to the physician or provider is to understand the label, inform the patient and any decision to prescribe should be done in consultation with the patient.