Any antibiotic, chemical or drug based substance consumed during pregnancy may reach the fetus (the baby inside the uterus) through maternal circulation. Antibiotics that are able to cross the placenta are potentially harmful and cause adverse fetal effects during pregnancy. The effects depend highly on the type and dose of antibiotic. Not only in pregnancy but certain antibiotics are able to pass from mother to her baby through breast milk.
The Food and Drug Administration (FDA) established five pregnancy categories to indicate the risk level of drugs to the fetus. The categories are A-B-C-D and X. The category A being the least dangerous during pregnancy and category X to be completely avoided
Category X: Highly dangerous
Adequate well-controlled or observational studies in animals or pregnant women have demonstrated positive evidence of fetal abnormalities or risks.
Quinolones: Sparfloxacin (1st trimester)
Adequate well-controlled or observational studies in pregnant women have demonstrated a risk to the fetus. However, the drug may be acceptable if needed in a life-threatening situation or serious disease for which safer drugs cannot be used or are ineffective.
Tetracycline: Tetracycline, Doxycycline, Oxytetracycline
Others: Naproxen (3rd trimester)
Animal studies have shown an adverse effect but there are no adequate and well-controlled studies in pregnant women.
Quinolones: Cipro-floxacin, Levofloxacin, Moxifloxacin, Gatifloxacin, Ofloxacin, Sparfloxacin (2nd and 3rd trimester)
Animal studies have shown an adverse effect, but adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus in any trimester.
Penicillin: Amoxicillin, Ampicillin, Cloxacillin, Flucloxacillin
Cephalosporins: Cephalexin, Cefradine ( First generation); Cefuroxime ( Second Generation); Cefixime, Cefpodoxime, Cefotaxime, Ceftriaxone ( Third Generation)
Macrolides: Azithromycin, Erythromycin
Others: Metronidazoles, Naproxen (1st and 2nd trimester)
Category A: Least dangerous
Theoretically there are no antibiotics in this class for pregnancy.
Md Sojib Khan is a Pharmacist.
Source: The Daily Star, November 22, 2008