Because I don’t trust that your high school properly taught you about menstruation, I’m going to give a little overview of that. Women are born with all of the eggs that they will have in their lives, which mature in the ovaries between childhood and puberty. Menstruation (aka “period” or “cycle”) is caused by hormones like estrogen and progesterone. During puberty, hormones cause microscopic eggs in the ovaries to finish maturing so that they can be fertilizes by sperm cells. Hormones also prepare the uterine lining by thickening it so as to hold a fertilized egg deposited by the Fallopian tubes.
If pregnancy does not occur, the unused material is ejected from the uterus, causing bleeding that lasts 5-7 days. If pregnancy does occur, some of this material might still be shed, which is why some women bleed even when they are pregnant. Particularly fertile women bleed throughout their pregnancy.
Menstruation is a cycle that lasts approximately 28 days. it is not merely the one week of bleeding. Menstruation begins with the menarche, the first bleed, when a girl is in the middle of puberty. The age of menarche has been decreasing in the past 200 years from 16-17 to 12-13. Asian girls tend to start later than Western girls. It is speculated that this is because of early sexualization that is more prevalent in Western cultures.The lower a girl’s BMI and more consistent that BMI is throughout her childhood, the later her menarche will occur.
Contrary to popular belief, women are the least hormonal during their period and the most hormonal about two weeks later (which is why PMS is Post-Menstrual Syndrome). Your physical condition can affect if you have a period. Women who are abused, dehydrated, or malnourished can go years without a period because their bodies aren’t healthy enough to start the process. Menopause is when the period stops around age 50 because hormone production drops too much to produce eggs.
You should also understand how the development process works. Hereâ€™s a weekly breakdown:
1: The last period before fertilization occurs (not pregnant yet)
2: Ovulation begins as the egg prepares to be released into the fallopian tube (not pregnant yet)
3: The sperm travels through the uterus to the egg and fertilizes it (fertilization)
4: The fertilized egg (zygote) travels from the fallopian tube to the womb (now, the mother is pregnant)
5: The zygote attaches to the inner lining of the womb
6: The ball of cells will become an embryo as the spinal cord and organs begin to develop, nurtured by the umbilical. Embryo is the size of a poppy seed
7: Intestines, arms, and legs sprout. Embryo is the size of a sesame seed
8: Heart beats and facial features develop. Embryo is the size of a lentil
9: Organs begin to work, limbs begin to move
10: Genitals, ankles, fingers, and toes begin to form
11: Embryo becomes a fetus. Limbs move, vital organs functional, nails growing
12: Fetus the size of a fig. Bones hardening and lungs working
13: Brain developing, continuous twitching and moving begins
14: Hair growth. Genitals developed enough to estimate sex
16: Fetus the size of an avocado. Liquid lung work, body systems functioning
18: Gender determined via ultrasound
19: Senses develop, kidney working
27: Fetusâ€™ cycle begins for feeding, sleeping, and moving
28: Fat layers and bones develop. Fetus becomes a baby and detects lights
32: Male genitals move into place. Skin is smooth and hair has formed on head
34: Temperature regulations begins. Safe to deliver baby (Vitality)
37: Baby is full-term
40: Due date. Inducing is possible. Skull is formed, but not solid, so vaginal birth is still possible