The Food and Drug Administration lists antibiotics in categories based on safety for use during pregnancy. The categories are A, B, C, D and X. Typically, medications in categories A and B are generally considered safe for use during pregnancy, though there are some exceptions to this rule.

Before administering an antibiotic in pregnancy, doctors at the Yale University School of Medicine, Brigham and Women’s Hospital, Faulkner Hospital and Harvard Medical School offer guidelines for antibiotic use during pregnancy. 

Using antibiotics during pregnancy

According to doctors and researchers, a few guidelines should be followed before prescribing an antibiotic to a pregnant patient:

• Only use antibiotics if no other treatment option will suffice.
• Avoid prescribing antibiotics during the first trimester when possible.
• Choose a safe medication (typically an older antibiotic tested on pregnant women).
• Choose single prescriptions over polypharmacy when possible.
• Dose at the lowest possible amount proven effective.
• Advise patients not to use over the counter medications during antibiotic treatment.

Antibiotics generally considered safe for use during pregnancy

Some of the common infections during pregnancy that require antibiotic treatment include urinary tract infection, bladder infection, pyelonephritis and appendicitis. This is not a complete list of infections that require antibiotic treatment.

If your physician prescribes an antibiotic for use during pregnancy, it is extremely likely that the drug falls into either Category A or Category B on the FDA list of approved drugs for use during pregnancy. Some of the antibiotics that may be prescribed safely during pregnancy include:

• Amoxicillin
• Ampicillin
• Clindamycin
• Erythromycin
• Penicillin
• Ampicillin-Sulbactam
• Ceftriaxone
• Cefixime
• Metronidazol
• Cefotetan
• Cefazolin
• Cefoxitin

New antibiotics


There is very little clinical information on the effect of new antibiotics on pregnancy and fetal complication risk. Decades ago, pregnant women were allowed to participate in drug testing so older antibiotics are typically the first prescribed by obstetricians. However, in some cases, despite the lack of formula testing during pregnancy, obstetricians are faced with a risks versus benefits case. If the benefits of prescribing an antibiotic during pregnancy outweigh the potential risks, the antibiotic in question is chosen.

There are several antibiotics safely prescribed during pregnancy. If you have an infection and your obstetrician has prescribed an antibiotic, talk with your doctor about the possible risks of taking the medication. In some cases, as is the case with urinary tract infections, leaving the infection untreated poses a risk to the pregnancy and unborn fetus.