Browne and Venning1 first suggested that the excretion of pregnandiol could be used as a measure of progesterone production and therefore of corpus luteum function. Because the pregnandiol excretion increased markedly during pregnancy and disappeared completely at parturition, it was suggested that progesterone might be produced by the placenta after the second month of pregnancy. Browne and Venning1 and Jones and Weil2 have reported cases in which the corpus luteum of pregnancy was removed on the one hundred and twentieth and the fifty-fourth days, respectively, and the pregnandiol excretion subsequently remained within normal limits. These cases seem to lend additional support to the theory of a placental origin for progesterone during pregnancy. However, in both cases functional ovarian tissue remained.
It has recently been possible to study the pregnandiol excretion throughout pregnancy of a woman from whom all ovarian tissue was removed on the sixty-third day of