What antibiotics are safe during pregnancy?

From the Guidelines

Antibiotics during pregnancy should be used with caution and only when the benefits outweigh the risks, with safe options including penicillins and cephalosporins, while avoiding tetracyclines and trimethoprim in the first trimester. When considering antibiotic use in pregnancy, it's crucial to weigh the potential risks and benefits, taking into account the type of infection, the trimester of pregnancy, and the patient's medical history, including any allergies 1.

Key Considerations

• Penicillins, such as amoxicillin, and cephalosporins are generally considered safe during pregnancy, with dosages similar to those for non-pregnant individuals, such as amoxicillin 500mg three times daily for 7-10 days 1.
• Macrolides like erythromycin are also considered probably safe, especially for patients allergic to penicillin, although the specific dosage may vary depending on the infection being treated 1.
• Tetracyclines, including doxycycline, should be avoided due to the risk of tooth discoloration and inhibition of bone growth in the fetus, as well as potential maternal hepatotoxicity 1.
• Trimethoprim should be avoided, especially during the first trimester, due to its potential effects on fetal development, although it may be used in short courses if no safer alternatives are available 1.
• Aminoglycosides, such as gentamicin and tobramycin, should be used with caution and monitored closely due to the risk of fetal ototoxicity and nephrotoxicity, with once-daily dosing preferred and monitoring of renal function in the neonate 1.

Decision Making

The choice of antibiotic should be guided by the severity of the infection, the specific pathogen involved, and the patient's individual circumstances, including any history of allergies or previous adverse reactions to antibiotics 1. Healthcare providers should consult the most recent guidelines and consider the FDA pregnancy categories when selecting an antibiotic for use during pregnancy. Untreated infections can pose significant risks to both the mother and the fetus, including preterm labor and maternal sepsis, making appropriate antibiotic treatment crucial when the benefits outweigh the risks 1.

From the FDA Drug Label

1. 1 Pregnancy Teratogenic Effects: Reproduction studies have been performed in mice and rats at doses up to 2000 mg/kg (3 and 6 times the 3 g human dose, based on body surface area). There was no evidence of harm to the fetus due to amoxicillin. There are, however, no adequate and well-controlled studies in pregnant women Because animal reproduction studies are not always predictive of human response, amoxicillin should be used during pregnancy only if clearly needed.

Use in Pregnancy: Amoxicillin should be used during pregnancy only if clearly needed, as there are no adequate and well-controlled studies in pregnant women, although animal reproduction studies have shown no evidence of harm to the fetus 2.

• Key Considerations:
  • No evidence of harm to the fetus in animal reproduction studies
  • No adequate and well-controlled studies in pregnant women
  • Use only if clearly needed
  • Animal reproduction studies may not always be predictive of human response

From the Research

Antibiotic Use in Pregnancy

• Antibiotics are commonly prescribed during pregnancy, with approximately one in four women receiving an antibiotic prescription, accounting for nearly 80% of prescription medications in pregnant women 3.
• The use of antibiotics during pregnancy is associated with both short-term and long-term effects on the newborn, including congenital abnormalities, changes in gut microbiome, asthma, and atopic dermatitis 3.
• Physiologic changes in pregnancy, such as increased glomerular filtration rate, total body volume, and enhanced cardiac output, may lead to pharmacokinetic alterations in antibiotics, requiring dose adjustment or careful monitoring and assessment 3.

Safe and Effective Antibiotics in Pregnancy

• Antibiotics such as beta-lactams, vancomycin, nitrofurantoin, metronidazole, clindamycin, and fosfomycin are generally considered safe and effective in pregnancy 3, 4.
• Fluoroquinolones and tetracyclines are generally avoided in pregnancy due to potential risks to the fetus 3, 4, 5.

Considerations for Antibiotic Selection

• The selection of an antibiotic during pregnancy depends on the likely pathogen, stage of pregnancy, special pharmacokinetic factors, safety of the drug, and cost 4.
• The choice of an appropriate antimicrobial agent must be weighed against the potential adverse outcome of a particular infection, the drug safety, and spectrum of activity 4.
• It is essential to consider the trimester of pregnancy when selecting an antibiotic, as some antibiotics are safe for use throughout pregnancy, while others are contraindicated or should be avoided in certain trimesters 4, 5.

Risks and Benefits of Antibiotic Therapy

• Untreated infections during pregnancy can lead to significant morbidity, including low birth weight, preterm birth, and spontaneous abortion 3.
• Antibiotic therapy during pregnancy can have benefits, such as preventing maternal and neonatal complications, but also carries potential risks, including antibiotic resistance and long-term consequences for the newborn 6.
• The use of antibiotics during pregnancy should be carefully considered, balancing the benefits and risks, and taking into account the latest evidence and guidelines 6.