A population-based case-control teratologic study of oral chloramphenicol treatment during pregnancy.

The objective of the study was to check the human teratogenic potential of oral chloramphenicol treatments during pregnancy. Pair analysis of cases with congenital abnormalities and matched population controls was performed in the large population-based dataset of the Hungarian Case Control Surveillance of Congenital Abnormalities, 1980-1996. Of 38,151 pregnant women who had babies without any defects (control group), 51 (0.13%), while of 22,865 pregnant women who had newborn infants or fetuses with congenital abnormalities, 52 (0.23%) pregnant women were treated with oral chloramphenicol. The case-control pair analysis did not show any human teratogenic potential of chloramphenicol during the second-third months of pregnancy in the different groups of congenital abnormalities. The occurrence of chloramphenicol treatment in the total control group as referent was compared with the occurrence of chloramphenicol treatment in the different congenital abnormality groups during the second-third months of gestation (i.e., in the critical period for major congenital abnormalities) and a higher adjusted OR for this drug was found only in the group with undescended testis based on only two cases. At the evaluation of medically documented chloramphenicol treatment a higher OR was not found in any congenital abnormalities. Thus, chloramphenicol treatment during early pregnancy presents little, if any, teratogenic risk to the fetus in humans.