There is a complex network of hormones at play within a woman's body that are involved in reproduction and fertility.

The four key hormones are Follicle-Stimulating Hormone (FSH), Luteinising Hormone (LH) Oestradiol (Oestrogen)and Progesterone.  Each hormone plays a vital role in the menstrual cycle rising and falling during each phase. 

It is important to note that each woman's menstrual cycle is unique to her, as an individual.