Abstract: By administration of sulfated cyclodextrin on a pregnant mother, the effect of a teratogen on a developing fetus is blocked. Blocking the effect of the teratogen reduces congenital defects in a developing fetus. The sulfated cyclodextrin has also been found to reduce the effect of the teratogen on a host. The sulfated cyclodextrin is administered either before or after onset of organogenesis and either before or after exposure to the teratogen. Teratogens include radiation, temperature extremes, chemicals, drugs, bacteria, viruses, hormones, stress, injury, pregnancy, and fatigue.