Summary
The hemostatic effect of progesterone administered vaginally at a dose of 100 mg twice
a day throughout one menstrual cycle was investigated and compared with the coagulation
factors in one untreated normal menstrual cycle in 15 women. The progesterone treatment
resulted in a 20-fold progesterone rise in the early follicular phase from 1.2 nmol/1
in the pretreatment control cycle to levels between 26 and 29 nmol/1 during treatment.
Ovulation was completely suppressed in seven women while eight women showed a slight
rise in progesterone on treatment days 20 to 25 not compatible with the rise which
could have been expected if ovulation had occurred. The effects found on haemostasis
during progesterone treatment varied with the menstrual cycle and were so small that
they could as well be due to chance and not to treatment.