Stimulation is started with a dose of rFSH (rFSH=recombinat follicle stimulating hormone) calculated according to the dose algorithms used in the two groups. The name of the gonadotropin preparation, the dose and number of treatment days will be recorded. The same applies for all drugs used. Monitoring will be performed with mandatory estradiol on the day of stimulation start and on stimulation day 6. The dose of gonodotropin can be adjusted on day 7. If estradiol is > 1200 pmol/l the dose is reduced with one step according to the dose algorithm. If estradiol is < 350 pmol/l the dose is increased with one step according to the dose algorithm. Vaginal sonography is performed on stimulation day 9-11 to estimate the number and size of follicles. The number of follicles >10 mm at sonography 0-2 days before ovulation induction is recorded. Ovulation induction with 6500 IU (IU=international units) rHCG (rHCG=recombinant human chorion gonadotropin ) is given when >=2 follicles >=17 mm. 36 hours after ovulation induction transvaginal oocyte pickup is performed according to standard procedure at the clinic using sedation and paracervical administration of local anaesthetics, and all follicles > 10 mm are punctured. The oocytes will be fertilized using standard IVF procedure. In the case of an unexpected poor semen sample on the day of ovum pick-up microinjection will be performed. The fertilization rate is recorded. Embryo transfer is done on day 2 or 3 according to routine procedures in the clinic. In the case of no GQE (GQE=good quality embryos ) it is allowed to perform double embryo transfer, otherwise single embryo transfer is mandatory. Luteal phase support using vaginal route is given from the day of embryo transfer and for 14 more days, until pregnancy test (urinary ). In case of impending OHSS (OHSS=ovarian hyperstimulation syndrome ), where decision is made to cryopreserve all embryos, the outcome of the first transfer of a cryopreserved embryo will be included in the study results for secondary endpoints. In case of pregnancy, an early vaginal sonography is performed in pregnancy week 7-8. The number of cancelled cycles due to poor response is recorded. The number of patients having moderate or severe OHSS, requiring intervention, will be recorded until four weeks after ovum pick up.