Significant differences were elicited when comparing days until HCG injection ( @ @ versus @ @ , p = @ ) , endometrial thickness ( mm ) ( @ @ versus @ @ , p < @ ) , serum levels of mid-luteal and midcycle estradiol ( p < @ ; Figure @ ) , LH ( IU/ml ) ( p < @ ) as well as mid-luteal progesterone ( p < @ ) .