So Uhm...What the Frick Really Goes Down in Our 28 Day Menstrual Cycle?
I’m sure we all know about the 28 day cycle (for some ladies it may be a couple of days longer or shorter, this can vary). We also know about a certain process called ovulation that occurs somewhere in between those days, hormonal changes, possible associated mood swings…but there is much more to the 28 day cycle than all of the mentioned above you know… We can for instance track our fertile and not so fertile moments, we can track whether our cycle is irregular or not etc. So let get cracking with the basics. (source image)
So the first thing you need to know is that your menstrual cycle always, and I mean always starts on the first day you get your period, so that can be any day on the calendar right, depending on who you are. In this menstruation period, you can lose about 30 to 40ml of blood and if you flow heavier, then that can go up to about 80ml per cycle. Kinda weird to measure your own blood loss but you’ll notice when you’re forced to upscale your hygiene pattern frequency. So anyways, back to menstruation, this can last anywhere between 4 and 7 days, again this varies from woman to woman. (source)
Okay so day 1 is your first day of the menstrual cycle, blood shedding takes place, due to shedding of endometrium and died blood vessels in the uterine wall, and this lasts about 4-7 days. After that, the follicular phase (around day 5 to day 13) produces and releases the FSH hormone. (Follicle Stimulating Hormone). This FSH causes an egg cell to mature and for the endometrium lining to thicken.
So inside your ovaries, there are female egg cells, and every egg cell is protected inside a sac called follicles, and these follicles produce the hormone estrogen, the bigger the follicle grows, the higher the estrogen produced, and then high concentration of estrogen will produce the hormone LH (Luteinizing Hormone),which if this hormone's concentration gets high enough, it triggers ovulation.
So in summary: high FSH -> high estrogen -> high LH -> Ovulation
The follicular phase is where your uterine restores itself and thickens up its endometrium wall (or the lining of the uterus/womb) in expectation of a potential embryo (fetus/baby). So as it does that, then around day 14, an ovulation takes place, which is the moment where one of your ovaries releases a matured egg cell into the fallopian tube. (source image)
So if we assume ovulation takes place at or around day 14, you must consider yourself potentially fertile 3 days before ovulation (so day 11,12 and 13) and 3 days after ovulation (day 15, 16 ad 17). So you have a potential fertile window of 7 days. Now pay attention… it takes about 72 hours for the egg cell to travel from the ovary to the uterus, and a conception takes place in the fallopian tube, so that means in theory, technically, you got about 72 hours in conceiving a baby per menstrual cycle. If a fertilized egg imbeds itself into the fallopian tube instead of the uterus, then we have an ectopic pregnancy case.
After day 18, the luteal phase takes place, this is where the remaining follicle, which is empty now, produces progesterone. Now this hormone is important for thickening of the endometrium so a fertilized egg can be imbedded in it. Now after day 25 you uterus will prepare for a new menstrual cycle if no fertilization took place, so between day 25 and day 28, the endometrium starts to detach itself and then from day 28 to day 1, the whole process starts again. (source image)
So here's a quick recap:
- Day 1-7: Menstrual flow
- Day 7-14: Follicular phase, FHS + estrogen + LH production, egg cell maturation
- Day 14: Ovulation -> egg cell release into fallopian tube , fertile window -> 2/3 days before and after ovulation
- Day 15-28: Luteal phase: Progesterone production, thickening endometrium
- Day 28-1: Detachment of endometrium (in case of no pregnancy), preparation for new menstrual cycle
- It is rarely the case that one egg cell will be fertilized with 2 or more sperm cells (dispermy/polyspermy), because after fertilization takes place, a cortical reaction occurs to prevent polyspermy. In other words, the egg cell forms some sort of an “iron” buffer so no other sperm cells can enter. However of course, there have been cases where this has still occurred but this leads to a spontaneous abortion due to an excess in chromosome count.
- In some cases, 2 egg cells get matured and go through ovulation, so if they both get fertilized then non identical twins can be expected. And in the case of identical twins, then 1 egg cell is fertilized, however during the early division processes, the clump of cells may fall apart into 2 separate clumps and this may result in identical twins.
Hope this was helpful, let me know your thoughts, xoxo
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