| Agent | Risk Category | Fetal effects | Maternal effects | Excretion route | Half-life T 1/2 (h) |
| Considered Safe | |||||
| Natural penicillins (e.g. penicillin G) | B | None Known | Allergic | Renal | 0.5 |
| Aminopenicillins (e.g., ampicillin) | B | None Known | Allergic, rash in 5 to 7% | Renal | 1.0 |
| Antistaphylococcal (e.g., nafcillin) | B | None Known | Allergic | Renal, hepatic | 0.5 |
| Antipseudomonal (e.g., ticarcillin) | B | None Known | Allergic | Renal | 1.2 |
| Extended spectrum (e.g. piperacillin) | B | None Known | Allergic | Renal | 1.0 |
| Cephalosporins (1st, 2nd, 3rd, 4th generations) | B | None Known | Allergic, bleeding if methylthiotetrzole, side chain | Renal, hepatic | 0.5 to 0.8 |
| Erythromycin (base, stearate or ethylsuccinate) | B | None Known | GI upset, allergic | Hepatic | 2.0 to 4.0 |
| Clindamycin | B | None Known | Pseudomembranous colitis | Hepatic | 2.4 |
| Spectinomycin | B | None Known | Allergic | Renal | 2.0 |
Probably safe-use with caution |
|||||
| Azithromycin | B | None Known | Occasional GI upset | Hepatic | 68 |
| Aztreonam | B | None Known | Rash, elevated serum transaminases | Renal | 2.0 |
| Gentamicin | C | None Known, but ototoxicity reported with other aminoglycosides | Increased neuromuscular blockade | Renal | 2.0 |
| Imipenem-cilastatin | C | None Known | Allergic, rarely seizures | Renal | 1.0 |
| Metonidazole | B | None Known | GI symptoms, reversible neuropathy, intolerance to alcohol | Renal | 8.0 |
| Nitrofurantoin | B | None Known | Hemolysis if G6PD deficiency present, neuropathy | Renal | 0.3 to 1.0 |
| Sulfonamides | B; D at term | Hemolysis if G6PD deficiency present; avoid at term | Allergic | Renal | Variable |
| Trimethoprim | C | Folate antagonism, possibly teratogenic; avoid in 1st trim | Allergic | Renal | 11.0 |
| Vancomycin | C | None Known | Allergic, hearing loss rarely, hypotension if given too rapidly | Renal | 6.0 |
Contraindicated |
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| Tetracyclines | D | Discoloration of decidual teeth; inhibiton of bone growth | GI symptoms, hepatotoxicity, renal failure | Renal | 8.0 to 19.0 |
| Fluoroquinolones | C | Insufficient information in humans; arthropathy reported in immature animals | Rare | Renal, hepatic | 4.0 to 8.0 |
| Streptomycin, kanamycin | D | Eighth cranial nerve damage | Ototoxicity, nephrotoxicity | Renal | 2.0 to 3.0 |
| Erythromycin estolate | B | None Known | Hepatotoxicity | Hepatic | 2.0 to 4.0 |
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