I have found that far too many women do not know anything about their periods or their menstrual cycles. Even the words seem to be a jumble as many are not sure which terms mean which things. (Is the egg what comes out when we have a period? Is ovulation the same as menstruation? What are all of those anatomy terms?) Instead we cover it up with innuendo and (not so) cute nicknames like Aunt Flow, the curse, or "that time of the month". So, instead of perpetuating the mystery of menstruation, lets talk about the basics. What is your period?
In order to define what your period is, first you must understand the difference between menstruation and the menstrual cycle. Once a young woman reaches puberty, she will begin her menstrual cycle. It is a continuous cycle with 3-4 phases (depends on who you talk to). When one phase ends, the next begins. The last phase of one cycle leads right into the first phase of the next. Menstruation or the menstrual phase (AKA: your period) is the first phase in the menstrual cycle. This means that the first day of each period is the first day of a brand new cycle. Although it is the first phase in your menstrual cycle, we are going to talk about it last because it just makes more sense that way.
The second phase of the menstrual cycle is known as the follicular phase. It begins when your period is over. When we are born we have ovaries full of primitive egg cells. Once we reach puberty and our menarch (this is the name for your first period), we have hormones working to turn those primitive egg cells into mature eggs that can be fertilized. Each egg sits inside of a little pouch called a follicle (hence the name follicular phase) while it is maturing. We generally have 1-2 eggs maturing for every menstrual cycle. This number often goes up around the age of 35.
While this is happening, we have a hormone called estrogen building up a nice, thick lining in our uterus. This lining is called the endometrium. If the cycle results in a pregnancy, the embryo will implant, or bury itself, into the endometrial lining of the uterus, and the thicker and healthier the lining, the better it can nourish the embryo.
This brings us to ovulation. Once the egg(s) has matured and the endometrium has been built up nicely, the follicle (the pouch containing the egg) will rupture. It literally bursts open, releasing the egg. Some people consider ovulation to be an entire phase unto itself, but I do not. Ovulation is the split second that that follicle ruptures and the egg is released, so because it is merely a moment in time, I don't feel that it is long enough to be its own phase, but rather the transition point between phases.
Once the follicle has ruptured and released the egg, you are now in the luteal phase. The ruptured follicle now turns into scar tissue known as the corpus luteum for which the phase is named. The corpus luteum remains on the outside of the ovary and produces estrogen and progesterone, two hormones very important to maintaining a pregnancy. We already know that estrogen helps to build a nice thick lining to nourish the embryo (baby). Progesterone is the hormone that prevents the endometrium (uterine lining) from shedding. After ovulation, two things can happen to the egg. It can be fertilized by sperm or not. Fertilization generally happens inside of the fallopian tube, and that fertilized egg (also known as a zygote or blastocyst) will travel down the tube to the uterus. Once inside of the uterus, the fertilized egg will burrow into the endometrium in an act called implantation. Implantation usually happens about a week after ovulation, give or take, and may result in a bit of spotting (called implantation bleeding) and/or cramping. This spotting or cramping is very mild and generally doesn't last more than a day. This is the beginning of pregnancy. Once implantation happens, the corpus luteum receives signals to continue producing estrogen and progesterone, thereby supporting the pregnancy.
If the egg is not fertilized, it will generally break down within about 24 hours. The luteal phase generally lasts about 2 weeks, wherein the corpus luteum continues producing estrogen and progesterone to foster any potential pregnancy. If there has not been implantation, the corpus luteum will break down toward the end of the phase, and the decrease in hormones causes the next phase.
This is the phase that many of us are most familiar with. The menstrual phase is your period, and as we said before, it is also the first phase in your menstrual cycle. If pregnancy occurs, we do not move on to the menstrual phase. Some women experience a bit of spotting around the time they would normally get their period. This is known as breakthrough bleeding, and is generally not a sign that anything is wrong, but it is still a good idea to mention it to your care provider. If the egg is not fertilized and does not implant, the corpus luteum will break down and stop producing estrogen and progesterone. The decrease in estrogen means that the endometrial lining of the uterus begins to break down, and the decrease in progesterone means that it will begin to shed. The blood that you see with your period is the endometrium shedding. Basically, your uterus is cleaning itself out, and starting again. When the endometrium breaks down, we build another one in its place, so that our uterus is nice and fresh in the event that we get pregnant with this next cycle. What you may (or may not) feel as cramps are actually uterine contractions. Much like in childbirth, our uterus contracts to expel its contents. In the case of childbirth, we are expelling a baby, in the case of menstruation, the uterine lining.
So how does all of this change with hormonal birth control? Basically, the pills, shots, patches, rings, etc release artificial versions of the same hormones that your body produces naturally, inhibiting your body from making them. This means that although you may still get your period while on birth control, it is more than likely that you are not ovulating. That last row of pills are actually placebos, which mimics the breakdown of the corpus luteum. Basically, hormonal birth control mimics, but also prevents you from having a cycle.
In the next installment, we will talk about several options that women have to manage their menstrual flows. Do you have any questions about your period? Post them in the comments! (It can be anonymous.)