antibiotics in pregnancy

Last edited 06/2020 and last reviewed 05/2023

During Pregnancy

Penicillins and Cephalosporins are drugs of choice in pregnancy and breastfeeding (1).

In pregnancy, avoid quinolones, tetracyclines, aminoglycosides, unless severe or life threatening infection, high dose metronidazole, trimethoprim (in first trimester - folate antagonist) and nitrofurantoin (at term - risk of neonatal haemolysis) (2).

BNF guidance with respect to antibiotic use in pregnancy states:

• penicillins and cephaloridines are safe to use throughout pregnancy
• sulphonamides interfere with the bile conjugating mechanism of the neonate, thus sulphonamides should be avoided if delivery is imminent
• tetracylines should not be used in pregnancy. This group of drugs stain developing bone and teeth in the foetus. Also the use of tetracylines, when administered intramuscularly, has occasionally produced maternal liver failure
• erythromycin - not known to be harmful
• metronidazole - manufacturer advises avoidance of high-dose regimens
• streptomycin may cause foetal auditory nerve damage
• trimethoprim - this is safe after the first trimester. However, the sulphonamide warning applies for trimethoprim - sulphonamide preparations

Breastfeeding

Penicillins and Cephalosporins are drugs of choice in breastfeeding (1).

A review has stated (3):

• Safe for administration:
  • aminoglycosides
  • amoxicillin
  • amoxicillin-clavulanate
  • antitubercular drugs
  • cephalosporins
  • macrolides
  • trimethoprim-sulphamethoxazole
  • trimethoprim - the BNF states that '..short-term use not known to be harmful'
    
    
• Effects not known/to be used with caution:
  • chloramphenicol
  • clindamycin
  • dapsone
  • mandelic acid
  • nalidixic acid
  • nitrofurantoin - the BNF states '..avoid; only small amounts in milk but could be enough to produce haemolysis in G6PD-deficient infants..'
  • tetracyclines
    
    
• Not recommended:
  • quinolones

Information about metrondiazole and breast feeding is linked.

Note that the summary of product characteristics must be consulted before prescribing any drug in pregnancy and during breastfeeding.

Reference:

1. NHS Forth Valley. Empirical Antimicrobial Guidelines for Forth Valley Hospitals 2013-2015
2. BNF Appendix 4:Pregnancy.
3. Mathew JL. Effect of maternal antibiotics on breast feeding infants Postgrad Med J 2004;80:196-200.