Effect of in vitro embryo culture conditions on metabolism of optimal human embryos in infertile couples

INTERVENTION: Randomized cultivation of human embryos with different levels of oxygen (5% versus 20%) from the day of fertilization (day 0) till the day of embryo transfer (day 5). On the day 3, the best embryos (based on morphokinetics) will be cultivated separately till the day 5. On the day 5, blastocyst media of the transffered embryo will be analyzed by LC‐MS/MS ( liquid chromatography‐mass spectrometry) to identify specific metabolic amino acid profile of the transffered embryos. CONDITION: infertility PRIMARY OUTCOME: Amino acid profiles of transffered embryos ‐ assessed by LC‐MS/MS (liquid chromatography‐mass spectrometry) Clinical Pregnancy Rate (CPR) ‐ assessed by serum hCG assay and fetal ultrasound Fertilization Rate (FR) ‐ assessed by checking pronuclear stage of oocytes on day 1 by microscope evaluation SECONDARY OUTCOME: Live birth rate (LBR) ‐ assessed by live birth of a child INCLUSION CRITERIA: Infertile patients in stimulated cycles