Which hormone's concentration peaks around day 14 of the menstrual cycle?

The hormone that peaks around day 14 of the menstrual cycle is estrogen. Specifically, this peak occurs during the follicular phase, which is the phase leading up to ovulation. Estrogen is produced by the developing follicles in the ovaries, and its levels rise as the follicles mature. This surge in estrogen serves important functions: it helps stimulate the thickening of the uterine lining to prepare for potential implantation of a fertilized egg and also plays a key role in triggering the surge of luteinizing hormone (LH) that leads to ovulation.

Estrogen's peak around day 14 is particularly significant because it signals the body that ovulation is imminent, impacting other hormones and processes involved in the menstrual cycle. Following this peak, estrogen levels will decrease slightly, while progesterone levels will rise in the luteal phase after ovulation occurs. Understanding these hormonal changes is crucial for comprehending the menstrual cycle and its regulation.