Inclusion Criteria:  Age of female patient 42 years or less Normal uterine cavity All embryos are day 5 or day 6 frozen blastocysts  Exclusion Criteria:  History of recurrent implantation failure Previously known major thrombophilia factors Non-compliance to given protocol Endometrial thickness < 7mm after 13 days of priming with estradiol valerate pre-existing metabolic diseases (Diabetes Mellitus & Hypertension).