CAH is autosomal recessive; if a woman has previously had a child with CAH and again becomes pregnant the same paner, her fetus will have a one in four chances of having CAH. Because the period during which the genitalia of a female fetus may become virilized begins only 6 wk after conception, treatment must be instituted essentially as soon as the woman knows she is pregnant. Ref: Novak's Gynecology 14th edition, Page 1095 ; Medical care of pregnant patient (American college of physicians) 2nd edition, page 298, 299