We all know about them and many of us dread getting one each month, but what exactly are periods? Chances are you probably don’t remember the lesson from your female teacher in sex-ed class and there’s probably a lot more to periods than you even realize. Actually getting your period is only a small part of the whole menstruation cycle (which is divided into four different phases).
So what exactly happens during each phase?
Phase 1: Menstrual Phase
This is the phase where you actually get your period. Consider this day one of your cycle. This phase starts when the egg from the previous cycle wasn’t fertilized (aka you are not pregnant). Without a pregnancy, the levels of the hormones, estrogen and progesterone drop and the thickened uterine lining (which is no longer needed for a pregnancy) gets shed through the vagina (aka your period).
Phase 2: Follicular Phase
The follicular phase begins on the first day of your period (it overlaps with the menstrual phase) and goes until the beginning of ovulation. In this phase, the brain (the pituitary gland to be exact) releases follicle stimulating hormone, (FSH_. FSH is responsible for telling the ovaries to produce follicles and within each follicle is an immature egg. Only one egg (the healthiest) will mature and the rest of the follicles will be reabsorbed into the body. The maturing egg will set off a response for more estrogen to be produced which causes the uterine lining to begin thickening again.
Phase 3: Ovulation
The rising levels of estrogen from the follicular phase initiates the brain to release luteinizing hormone (LH) which sparks ovulation to occur. This is when the ovary releases the mature egg from the follicle and the egg travels down the fallopian tubes to be fertilized. This is the only time during the menstrual cycle that you can get pregnant and typically occurs around day 14 of the cycle. Sperm can live for up to 5 days, therefore a woman can get pregnant if they have sex up to 5 days before ovulation.
Phase 4: Luteal
When the follicle releases the mature egg, it turns into the corpus luteum. This causes estrogen and progesterone to be released which helps keep the uterus lining thick and prepared for a pregnancy. If you get pregnant, human chorionic gonadotropin (hCG) is released which maintains the corpus luteum and the uterine lining. If you do not get pregnant, the corpus luteum dissolves and estrogen and progesterone levels drop. This causes the onset of your period.
It’s pretty incredible that such a complex cycle is happening in our bodies each month without us even having to think about it. Just another reason to be proud to be a woman and celebrate our periods!