Effects of antibacterials on the unborn child: what is known and how should this influence prescribing.

Antibacterials are among the most commonly prescribed drugs worldwide. In general, infections occur in pregnant women at much the same rate as in the general population. However, as a result of physiological changes brought about by pregnancy, some infections, such as those of the urinary tract, may have an increased incidence. It is important to remember that almost every drug crosses the placenta, ensuring that the unborn fetus is also exposed. When prescribing an antibacterial agent to a pregnant woman, it is important that the mother is treated appropriately while at the same time protecting the unborn child. Certain factors need to be addressed, such as the possible teratogenic risk, changes in pharmacokinetics and the potential toxicity of the drug. In this paper we have reviewed various classes of antibacterials which are commonly used during pregnancy, including penicillins, beta-lactam inhibitors, cephalosporins, macrolides, aminoglycosides, tetracyclines, lincosamides, fluoroquinolones, sulfonamides, nitrofurans, and anti-tubercular agents. Some of these drugs have been on the market for many years, whereas others are relatively new and increasingly popular, despite the fact that the older drugs remain very effective. After reviewing the evidence-based information from epidemiological studies, it appears that most antibacterial agents can be used relatively safely during pregnancy. Women who are pregnant should not be denied appropriate antibacterial therapy because of a lack of information. It is possible to treat the mother, while protecting the unborn child, by prescribing an agent that the causative bacteria is sensitive to, rather than a perceived 'safer' option that may not effectively treat the infection and which may also add to the growing problem of bacterial resistance.