When it comes to your menstrual cycle, the count starts on the first day of menstruation as your vagina starts to bleed. On average, a woman’s menstrual cycle typically lasts 28 days, which means that your menstrual cycle can be divided into four main phases. These are
Menstrual Cycle Phase 1: Ovulation
The first stage or phase of your menstrual cycle is ovulation. A woman has two ovaries. These small, almond-shaped glands hold and develop a woman’s eggs. One egg, or ovum, is about the size of the head of a pin.
Want to hear something crazy? Girls are born with all the eggs they’ll ever have! About 250,000 in each ovary. Every month after your first period, a mature egg is released from an ovary. This is called ovulation.
Menstrual Cycle Phase 2: Fertilization
Next up is phase two of the menstrual cycle stage, fertilization. This occurs when an egg leaves the ovary. It’s then caught by the fringes at the end of one of the fallopian tubes and travels toward the uterus. This is where the whole “birds and bees” thing comes in. If a man and woman have sex while she is ovulating, her egg and his sperm can possibly join, causing fertilization. And that, my friends, is how babies are made.
Menstrual Cycle Phase 3: Embryo
After fertilization comes stage 3, the embryo phase of your menstrual cycle. Picture this: the uterus is a hollow, muscular organ about the size of a fist. Actually, it kind of looks like an upside-down pear. When a woman is pregnant, the fertilized egg starts to develop in the uterus. In the first eight weeks of pregnancy, that egg is known as an embryo; from that point until birth, it is referred to as a fetus.
Menstrual Cycle Phase 4: Menstruation
Menstruation, the fourth stage of your menstrual cycle, gets a little technical. Each month, a woman’s body prepares itself in case pregnancy occurs. The endometrium, or uterine lining, thickens to nourish a developing fetus. If the egg isn't fertilized, a woman doesn't become pregnant and the endometrium is shed. So, what is menstruation? Menstruation refers to the passing out of the body of the blood, tissue and fluids that make up the endometrium. This is what is going on inside of you once a month if you’ve started your period.
During a woman's period, menstrual fluid passes through the opening of the cervix (which is about the size of a match head) through the vagina and out of the body. (The cervix is the rounded lower portion, or neck, of the uterus, which protrudes into the vagina.)
Don’t worry, we’re almost done here. The vagina is a very flexible passageway that leads from the internal reproductive organs to the outside of the body. It’s also called the birth canal. Although the walls of the vagina usually lie flat against each other, they can greatly expand. This flexibility makes it possible for a baby to pass through the vagina during childbirth. (Ouch.) But it also makes wearing a tampon comfortable and easy, so at least there’s that.
That’s a wrap. More period questions? Head this way, or ask an expert.