to examine if a natural daytime variation in progesterone levels may explain parts of the inconsistent findings from studies reporting divergent results concerning this matter and will be carried out by several blood samples from the same patient during the day of ovulation triggering.

The impact of the progesterone level at the end of the follicular phase in stimulated IVF/ICSI cycles and its effect on the pregnancy rate and oocyte quality is controversial, which arises from conflicting results in retrospective studies and meta-analyses. This study is assumed to examine if a natural daytime variation in progesterone levels may explain parts of the inconsistent findings from studies reporting divergent results concerning this matter and will be carried out by several blood samples from the same patient during the day of ovulation triggering. If variation is present, the impact of variation on the developing oocyte and embryo quality will be estimated by embryo quality indicators.

Inclusion Criteria:

• patients 18-45 years
• BMI 18-35 kg/m2
• Menstrual cycle length 24-35 days
• Stimulation with rFSH or hMG

Exclusion Criteria:

• None

Patient who will undergo IVF treatment