What pre‑extraction antibiotic is recommended for a healthy 22‑week pregnant patient?

Pre-Extraction Antibiotic Prophylaxis for a Healthy 22-Week Pregnant Patient

For a healthy 22-week pregnant patient undergoing dental extraction, amoxicillin 500 mg orally 1 hour before the procedure is the recommended antibiotic prophylaxis, as beta-lactam antibiotics (penicillins and first-generation cephalosporins) are universally recognized as safe and effective throughout pregnancy. 1, 2

Recommended Antibiotic Regimen

First-Line Choice

• Amoxicillin 500 mg orally, single dose 1 hour pre-procedure is the optimal choice, as penicillins have extensive human safety data showing no teratogenic effects at therapeutic doses and are classified as Category A/B compatible throughout all trimesters 1, 2
• Amoxicillin achieves adequate tissue concentrations in pregnant patients, though maternal serum levels are significantly higher than placental and fetal tissues (2.18±1.30 µg/g vs 1.00±0.71 µg/g in placenta) 3

Alternative for Penicillin Allergy (Non-Severe)

• Cephalexin 500 mg orally, single dose 1 hour pre-procedure is appropriate for patients with non-severe penicillin allergy, as first-generation cephalosporins have moderate-quality evidence supporting safety throughout pregnancy with no demonstrated fetal harm 1, 4
• Cross-reactivity between penicillins and cephalosporins occurs in approximately 10% of patients, primarily with first-generation agents 4, 5

Alternative for Severe Penicillin Allergy

• Clindamycin 600 mg orally, single dose 1 hour pre-procedure should be used for patients with history of anaphylaxis, angioedema, respiratory distress, or urticaria following penicillin administration 1, 4
• Clindamycin has moderate evidence supporting its safety in pregnancy with no significant risks of congenital anomalies or preterm delivery 1

Critical Considerations at 22 Weeks Gestation

Pregnancy-Specific Pharmacokinetics

• Amoxicillin renal clearance increases significantly during pregnancy (T2: 24.8±6.7 L/h vs postpartum: 15.3±2.6 L/h), which may reduce drug concentrations, though standard prophylactic doses remain adequate for dental procedures 6
• Enhanced glomerular filtration rate, increased total body volume, and enhanced cardiac output during pregnancy may alter antibiotic pharmacokinetics 2

Safety Profile at Mid-Pregnancy

• Beta-lactam antibiotics are generally considered safe and effective throughout all trimesters of pregnancy 2, 5
• Approximately one in four women will be prescribed an antibiotic during pregnancy, with beta-lactams accounting for the majority of safe prescriptions 2

Antibiotics to Strictly Avoid

Contraindicated Agents

• Tetracyclines and doxycycline are strictly contraindicated after week 5 of pregnancy due to tooth discoloration, transient bone growth suppression, and potential maternal fatty liver of pregnancy 1, 5
• Fluoroquinolones should be strictly avoided due to potential toxicity for the unborn child 5
• Co-trimoxazole (TMP-SMX) should be avoided, especially during first and second trimester, due to increased risk of preterm birth, low birthweight, and neural tube defects 1

Common Pitfalls to Avoid

• Do not use second or third-generation cephalosporins (cefuroxime, cefixime) for routine dental prophylaxis, as first-generation agents have better gram-positive coverage and established safety profiles 4
• Do not withhold necessary antibiotic prophylaxis due to pregnancy concerns, as untreated infections during pregnancy are associated with significant morbidity including preterm birth and low birth weight 2
• Verify true penicillin allergy history carefully, as many reported penicillin allergies are not true IgE-mediated reactions, and unnecessary avoidance may lead to suboptimal antibiotic selection 4, 5
• Do not use amoxicillin-clavulanate for routine prophylaxis in pregnant patients, as it should be avoided in women at risk of preterm delivery due to very low risk of necrotizing enterocolitis in the fetus 1