The menstrual cycle stages can seem vague or too scientific unless you understand why, when and how it all works. After that it is a simple formula to follow.
The Menstrual Cycle Overview
As mentioned before, when tracking the days of the menstrual cycle, the first day of menstruation, or bleeding, is called Day 1 of that cycle. The cycle ends when menstruation begins again. This varies immensely from 20 to more than 90 days but a “typical” cycle would be from 26 – 32 days; with 28 being the optimum. In situations such as PCOD/PCOS – Polycystic Ovarian Syndrome – ovulation can be well past Day 20 and so the cycle would be much longer than 32 days. Women suffering from this tend to have lengthy cycles along with other common symptoms.
You do not even have to ovulate for it to appear you have completed a cycle. This is called break through bleeding and is common to women with hormonal imbalance.
Phases of the Menstrual Cycle
There are two phases. The first is the Follicular Phase which is when follicles are matured and hopefully one matured enough to make a healthy egg. The second phase is called the Luteal Phase. It has to do with ovulation and beyond. LH which is luteinizing hormone is the hormone that causes the release of the egg and from there fertilization determines how the rest of the cycle goes.
The length of the Luteal Phase, is the better indication of the quality of the cycle. The Luteal Phase will tell if the egg is healthy or not by how long it provides progesterone to the hormonal symphony. See the articles on Beyond Fertility about Luteal Phase Defect.
The primary hormones of the menstrual cycle are Follicle Stimulating Hormone (FSH), Estrogen (which is actually a name given to a group of 3 hormones) Luteinizing Hormone (as in the LH surge), Testosterone and Progesterone. The function of each of these follow according to the order in which they “appear” and “reappear” in the cycle.
In Toni Weischler’s book Taking Charge of Your Fertility (available in the Fertility Tracker store), it is explained best. She uses the mnemonic FELOP for the hormones of the synchronized cycle. The order is FSH (maturation of the follicle) Estrogen peak, LH – Luteinizing Hormone surge, then Ovulation, then Progesterone.
- FSH stimulates the follicles to mature and grow in estrogen.
- Then, when Estrogen rises to its peak…
- Luteinizing Hormone – LH, is signaled to spike and release the matured egg.
- Ovulation happens. The egg covering, called the yellow body or the Corpus Luteum, is a progesterone covering needed for pregnancy; should it occur. The CL is left behind in the matured follicle’s sac and heals over while signaling the making of hormones for possible pregnancy.
- Progesterone now becomes the dominant hormone for the luteal phase of the cycle. There will be a certain number of days when progesterone should be dominant, unless pregnancy occurs at which time progesterone will stay high until near to labor time.
- Broken down a little more, it is like this:
- FSH stimulates 15-20 follicles, on average each month, to begin to mature in each ovary.
- Each possible egg was once a follicle.
- These follicles are stimulated to produce oestrogen, which is ultimately needed for ovulation to occur.
- As the follicles mature they “ooze” estrogen into the blood stream (which shows in the saliva).
- As the follicles are stimulated one will mature to become the “egg of the month.”
- When a heightened level of oestrogen is seen by the hypothalamus it signals the pituitary to release a surge of LH.
- This LH spike causes the matured egg (from one of the follicles) to release from the ovary.
- The sac that is left in the follicle is called the Corpus Luteum (yellow body) and it heals up and causes the production of progesterone for the remainder of the cycle or for pregnancy.
- In some cases more than one will mature and be released causing twins or even triplets. Either ovary can release an egg depending on which is ripened first.
- How how long it will take to reach an estrogen peak or threshold determines how long this part of the pre-ovulation part of the cycle will last. The high levels of oestrogen cause the peak ferning days. Each day the ferns grow fuller shows the amount of estrogen that is coming from maturing follicles.
- The second half of the cycle begins; the part of the cycle that progesterone is now the dominant hormone and pregnancy can occur.
As we explained, the first phase is the Follicular phase, followed by the Luteal Phase and divided by ovulation. An ideal cycle would follow phases of the moon and be about 28 days. See our next post with a visual breakdown of the Menstrual Cycle. Menstrual Cycle 2