During menstrual cycle, levels of LH and estrogen are highest around

The secretion of gonadotropins (LH and FSH) increases gradually during the follicular phase and stimulates follicular development as well as secretion of estrogens by the growing follicles. Both LH and FSH attain a peak level in the middle of the cycle (about $14^{\text{th }}$ day). Rapid secretion of LH leading to its maximum level during mid-cycle called LH surge induces rupture of Graafian follicle and thereby the release of ovum (ovulation). Concentration of estrogen in blood is also high around $14^{\text{th }}$ day and reaches its peak.