What is a menstrual period and how does it work? Here we go with the easy version of periods: Once a month, your uterus sends blood through your vagina into the outside world. Menstrual periods arrive around age 9 to 14. This is a big change but it’s a perfectly normal part of growing up. Need to know more than the basics? Let's dig into Advanced Periods! Tissue from the uterine lining sloughs off, and that’s the period, aka blood coming out of your vagina. What a delight. It begins in the brain! Three hormones, gonadotropin releasing hormone (GnRH), luteinizing hormone (LH) and follicle stimulating hormone (FSH), are released from glands within the brain. These travel through the bloodstream to nudge eggs out of the ovary. As they grow, several egg follicles produce estrogen. This causes the uterine lining to thicken with more blood vessels in preparation for the egg’s release from its ovarian prison. It's ovulation time! Estrogen levels fall and LH surges, causing the ovary to release the egg into the fallopian tube. The egg lives for 12-24 hours. FSH peaks during ovulation, too, but no one really knows why. Freaky, huh? The egg makes its way to the uterus via the fallopian tube while the empty egg follicle — known as the corpus luteum — squishes out more and more estrogen + progesterone to get the uterus ready for a possible pregnancy. FSH and LH levels plunge. Hormonal hell -- everyone's favorite kind of purgatory. Progesterone level peaks. This hormone helps build up the uterine lining. High progesterone might be one of the causes of PMS. Bummer. If the egg was not fertilized, the corpus luteum falls apart and stops producing progesterone. A fertilized egg, called a zygote, keeps progesterone high, and this growing ball of cells becomes a blastocyst. Ok side note here: getting your period now means you could possibly get pregnant -- ie have a baby grow in your uterus -- if sperm shows up in your body. More on that later so we can focus on PERIODS. Estrogen levels decrease and progesterone production slows, causing the uterine lining to break down and shed — the egg goes with the flow. If you’re not pregnant, your period starts all over again. Hope you enjoyed this menstrual journey with us!
