The menstrual cycle is an important part of women's health and having a better understanding of it, could be of use to those trying to conceive.
It consists of two phases:
- The Follicular Phase—the part in which a follicle (fluid full sac within the ovary that contains an egg) grows over the course of 10-20 days (on average- but lengths can vary). As it grows, the follicle produces Estrogen which prepares the uterus for implantation. Ovulation happens once the follicle has reached a certain size and the resulting estrogen levels trigger a release of the hormone LH. It’s this “ LH surge” that initiates ovulation. The “fertile window” consists of the days leading up to ovulation.
- The Luteal Phase—The second part of the cycle which begins following ovulation, marked by a rise in the hormone Progesterone. Progesterone has an important job of maintaining a pregnancy should you get pregnant, but if pregnancy doesn’t occur, it slowly declines and results in a bleed (the period). This part of the cycle has less variability and is approx 14 days for everyone (regardless of the cycle length).
Importance of this is that people with longer menstrual cycles have a longer follicular phase and ovulate later, hence have fertile windows at a later point in their cycle!
(Ex: 35 day cycle—14 day luteal phase = 21 day follicular phase (fertile window approx CD 18-21) vs 28 day cycle -14 day luteal phase =14 day follicular phase (fertile window approx CD 11-14).
Hope this helps people out there stress less about when their fertile window is and gives you a better way to think about cycle tracking!
Understanding your menstrual cycle is key when determining when your “fertile window” is in order to plan when to have “timed intercourse.”