Your Menstrual cycle has 4 distinct phases:
- Menstruation
- Follicular
- Ovulation
- Luteal
These can be broken down into follicular (menstruation to ovulation) and proliferation (luteal to menstruation)
Follicular (Day 1 – Ovulation)
During this phase your body and reproductive system are preparing for a baby. Your ovaries are busy developing follicles that will turn into a mature egg ready to be released at ovulation. By day 8 your ovary has chosen an egg that will begin to mature for ovulation. Oestradiol (oestrogen) is gradually rising over this period as your eggs are developing into follicles.
Ovulation
Ovulation occurs after peak oestradiol is produced by the follicle. When oestrogen peaks a hormone triggers a surge in progesterone production. As we know progesterone is what makes our uterus prepare for a baby. Think of progesterone as the housekeeper making the bed for a new house guest. The egg is released from the ovary thanks to the presence of progesterone and another aiding hormone that stimulates the follicles in the ovary.
Luteal Phase (Ovulation to menstruation approx. 14 days)
Lasting 14 days from ovulation the site at which the mature egg was released becomes the corpus luteum. The corpus luteum increases progesterone production, leading to thickening of the uterine lining. Think of it as the housekeeper that is helping to make the bed. It is making sure that a big duck feather duvet is ready for your house guests. Day 8-9 post ovulation is peak implantation time, the bed is warm the duvet is full of duck feathers ready to be slept in. Towards the end of the 14 days, if no pregnancy occurs this corpus luteum notices that there is no house guest this month and begins to strip the bed and becomes thinner and thinner. As the corpus luteum thins there is a decrease in progesterone. This drop in progesterone is what triggers menstruation.
Menstruation
Lack of a fertilized egg leads to a drop in progesterone. This triggers the body to enter menstruation. That comfy duvet that your body worked so hard to make is now useless. So, we need to “strip the bed” in order to welcome a new potential guest next month. Your uterus begins to contract known as cramping. During this phase oestrogen begins to rise again as the follicles in the ovaries begin to grow and so the cycle of oestrogen and progesterone continues.
During each phase it is normal for your body to feel different. You experience different moods and emotions throughout your cycle. This is what we will explore in the weeks to come.
Until next time!
References
https://www.ncbi.nlm.nih.gov/books/NBK279054/