USE OF TETRACYCLINES IN PREGNANCY

The tetracyclines are a class of broad-spectrum antibiotics, which despite widespread bacterial resistance, are still useful in the treatment of chlamydia, rickettsia, brucella, Lyme disease, acne, destructive periodontal disease, exacerbations of chronic bronchitis, leptospirosis, and respiratory or genital mycoplasma infections. Available tetracyclines include: tetracycline, demeclocycline, doxycycline, lymecycline, minocycline, oxytetracycline and tigecycline. Doxycycline is also used for malaria prophylaxis in chloroquine-resistant areas and in the treatment of anthrax.

Exposure to tetracyclines in early pregnancy has not been convincingly associated with any specific malformation, however data for some tetracyclines are extremely limited or absent.  One study found a significant association with spontaneous abortion following exposure to tetracycline antibiotics.  No effect of antenatal doxycycline exposure on fetal birth weight or preterm delivery risk has been identified in two studies using data from the same cohort. Rates of pregnancy outcomes other than congenital anomalies have not been studied for tetracyclines as a group, or individually. Use of tetracycline antibiotics in the second or third trimester is associated with discolouration of deciduous teeth and there are limited data to support transient effects on fetal bone growth. Tetracyclines may exacerbate fatty liver of pregnancy. 

Where possible, antibiotic choice should be informed by culture and sensitivity tests in accordance with local prescribing guidelines, however, if treatment is required urgently or before test results become available, then tetracyclines may be considered during the first trimester if an antibiotic with a better fetal safety profile is not possible. Any risks to the fetus should be weighed against the potential adverse effects for the mother and fetus from an untreated infection.

Exposure to tetracyclines at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy or any additional fetal monitoring. However, other risk factors present in individual cases may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.