It is your brain (hypothalamus and pituitary) that produces hormones that signal the ovary to produce and usually select out only one follicle (the sac that contains the egg) out of many per month once your period starts.
The hypothalamus secretes GnRH hormone that triggers the pituitary to secrete both FSH and LH hormones. It is the FSH and LH hormones that help the ovary create and grow a follicle. Once the follicle is “mature”, the follicle tells the brain (the pituitary in particular) that it is ready to be ovulated through the sustained production of a large amount of estrogen (this is what gives you the egg white cervical mucus).
The pituitary reads this and in response, secretes a large amount of the ovulatory hormone (LH) to allow the follicle to ovulate the egg about thirty-six hours later.
Your Ovulation Predictor Kits OPK kits detect this “LH surge” and that’s how we know you’re going to ovulate. Once you have ovulated, the remaining follicle turns into the Corpus Luteum that creates lots of Progesterone for the next fourteen days.
It is the Progesterone that creates your rise in body temperature that is detected on BBTs and gives you many types of symptoms, such as breast tenderness. The Corpus Luteum only lasts for fourteen days and unless you’re pregnant, will die off and stopping the production of Progesterone and Estrogen. Once your uterus senses that there’s no more Progesterone or Estrogen, it sheds off it’s lining (a process commonly known as a period) and the cycle repeats itself.
This article was provided by Dr. Quintero, expert in reproductive medicine and founder of C.A.R.E. fertility. Originally published on FertilityTies