Exogenous Progestogen and Estrogen Implicated in Birth Defects

A five-year study of the possible teratogenicity of exogenous female sex hormones included three case-control studies and one cohort study. The first case-control study disclosed an estimated relative risk of 8.41 and a highly significant difference in maternal hormonal exposure ( P P =.017) and 3.35 ( P ( JAMA 240:837-843, 1978)