The 1980-1984 data base of the Hungarian Case Control Surveillance System for Congenital Anomalies was used to evaluate possible teratogenicity of
allylestrenol therapy during pregnancy. In an initial global analysis, three of the 24 congenital anomaly groups studied (ie,
clubfoot, multiple anomalies, and
hypospadias) had a significantly higher incidence of
allylestrenol use. A case control analysis, however, excluded a pathogenetic role for
allylestrenol in the etiology of
clubfoot and multiple congenital anomalies. A greater use of
allylestrenol in the first global evaluation was explained by a higher incidence in these groups of impending
miscarriage and
preterm labor, which are indications for
allylestrenol therapy. The case control analysis did indicate a greater use of
allylestrenol in the
hypospadias group, but this difference was not statistically significant in the critical period for induction of
hypospadias (ie, the third and fourth months of gestation). The causal role of
subfertility in the etiology of
hypospadias was an indirect factor, explaining the greater use of
allylestrenol during pregnancy in this group; in Hungary, women with a history of
infertility frequently receive hormonal support in the first trimester. The authors conclude that the data analyzed do not indicate any teratogenic effects of the use of
allylestrenol during pregnancy.