Participating sites consist of academic and non-academic hospitals and fertility clinics in The Netherlands. There are two treatment arms (MOH/IUI treatment with LPS vs MOH/IUI treatment with placebo) with a non-blinded superiority design. Participants are randomly distributed across both treatment arms for the entire study-period (six months, non-crossover).~Eligibility criteria are: 1) couples starting IUI with Mild Ovarian HyperStimulation (MOH), with the intend to receive this treatment for at least six months. 2) Indication for MOH/IUI treatment is in accordance with current (dutch) NVOG guidelines; Diagnosis of unexplained (primary or secondary) infertility with Hunault <30% (or >30%, after an expectant management period of at least 6 additional months). Total mobile sperm count (VCM) >10 million. 3) Females aged >18 years with regular menstrual cycle.~(Mild) Ovarian stimulating treatment and insemination are according to regular treatment protocol. Females assigned to the treatment group start LPS, applying 3dd200mg Utrogestan in vaginal capsules, on the day of IUI. Treatment is continued until the onset of menstruation, a negative pregnancy test, miscarriage or confirmed vital intra-uterine pregnancy at 7 weeks gestation.~Main outcome is pregnancy within 6 months of treatment, leading to Live birth. Secondary outcomes are; Clinical pregnancy rate. Miscarriage rate. Multiple pregnancy rate. Pregnancy complications. Perinatal outcomes. Side effects and compliance to therapy. Added Medication Costs. Budget impact.~The analyses will include a cost-effectiveness analysis.
The LUMO study is a multicenter, randomized controlled trial that evaluates the effectivity of luteal phase support in MOH/IUI treatment.