The objective is to test the hypothesis that luteal phase support with vaginal progesterone
leads to a higher clinical pregnancy rate (primary outcome) and live birth rate (secondary
outcome) when compared to no luteal phase support in a program of intrauterine insemination
(IUI) after controlled ovarian stimulation with gonadotrophins. Additionally, the length of
the luteal phase will be recorded (secondary outcome) in order to detect luteal phase
defects/insufficiencies in the absence of luteal phase suppletion as well as luteal phase
prolongation in case of luteal phase support which may be a burden for the patients waiting
for the outcome of the treatment.