Table 1.

Major milestones of progesterone research.

1897	J Beard	Absence of ovulation during pregnancy
1898	L A Prenant	Corpus luteum is necessary for implantation
1916	E Herrmann and M Stein	Extract from the corpus luteum blocks the ovulation
1923	W M Allen	Effect of the corpus luteum extract on castrated rabbit’s endometria
1931	L Haberlandt	Birth control through temporary hormonal sterilization
1933–1934	K H Slotta, P Wintersteiner, A Butenandt, U Westphal, W M Allen, M Hartmann, A Wettstein	Isolation of progesterone
1951	C Djerassi	First synthesis of an oral contraceptive norethindrone
1970	B W O’Malley	Progesterone receptors and isoforms