A population-based case-control study of the safety of oral anti-tuberculosis drug treatment during pregnancy.

OBJECTIVE

To study the human teratogenic potential of isoniazid and other anti-tuberculosis drug treatment during pregnancy.

DESIGN AND SETTING

Cases from a large population-based dataset at the Hungarian Case-Control Surveillance of Congenital Abnormalities, and controls from the National Birth Registry, between 1980 and 1996. Information on all oral anti-tuberculosis drug treatments during pregnancy was medically recorded.

STUDY PARTICIPANTS

Women who had newborns or fetuses with congenital abnormalities (case group), and women who had babies with no congenital abnormality (control group).

MAIN OUTCOME MEASURES

Congenital abnormalities in newborn infants and fetuses diagnosed prenatally during the second and third trimesters, and postnatally from birth to the age of one year.

RESULTS

Of 38,151 controls, 29 (0.08%) were exposed to anti-tuberculosis drug treatment during pregnancy; the corresponding figures for cases were 22,865 and 11 (0.05%). The prevalence odds ratio was 0.6 (95%CI 0.3-1.3). Analysis of isoniazid and other oral antituberculosis drug use during the second and third months of gestation, i.e., in the critical period for most major congenital abnormalities, in case-control pairs did not indicate a teratogenic effect of these drugs in any group with congenital abnormality.

CONCLUSION

Maternal exposure to oral anti-tuberculosis drugs during pregnancy did not show a detectable teratogenic risk to the fetus; however, the number of pregnant women who were treated with these drugs during the critical period of most major congenital abnormalities was limited (six cases vs. 21 controls).