As a heads up: words that have an asterisk* are glossary terms. Hover your cursor over the word and it’s definition will appear.
Our hormones are uh-may-zing. Even when they go all wacko (trust me, mine have been upside down, reversed, you name it), God orchestrates an incredible symphony inside of each of us to make us who we are as women. This page is meant as an overview to get you familiar with the major hormones that govern just about everything having to do with our secondary sexual characteristics (breasts, pubic hair, curves, etc.) and reproduction. For discussions on other hormone situations – pregnancy, menopause, what makes some women infertile, etc. – please visit those pages. I’ll also do a more in-depth discussion of these hormones in another page later if there is interest (let me know). Let’s get started!
We’re all different
First things first, your cycle* is different from everyone else’s. All of ours are. Don’t think that just because something is true for your sister, mom, or best friend that it will will also be true for you. If you have regular periods, though, it’s likely that your cycles will look similar to what is shown in textbooks. I’m going to walk you through the image at the bottom of this page so that we can get on the same page.
What’s going on at the cellular level in your ovaries
The image at the bottom visually describes the delicate interplay between your hormones and what is going on in your uterus throughout your cycle. We are going to look over the first row which is a depiction of ovarian histology*. This is what is happening on a cellular level in your ovaries every time one of them releases an egg. There is a ton of interplay between the hormones that makes this happen so I will refer back to different steps of ovarian histology when I talk about the different hormones. One cool thing to note is that your body temperature stays at a given level during the first part of your cycle (the follicular phase*), spikes at ovulation*, and then stays level at this now higher degree during the second part of your cycle (luteal phase*).
Hormones, hormones, hormones
We’ve got a lot of hormones! Check out the center part of the picture, the part of the graph with all lines of color…
The ones that come from your brain are follicle stimulating hormone (FSH, red line) and luteinizing hormone (LH, green line). They are called tropic hormones (trOpic – say the o sound hard unlike the word you would use when requesting a vacation to the South Pacific). That means they tell another endocrine gland* what to do (that would be your ovaries). So…FSH and LH are released in slowly increasing amounts to make the follicle* mature and eventually rupture. There’s a spike of both at ovulation.
The other 2 hormones that are important right now are the ovarian hormones. Those are estradiol (a specific type of estrogen – they can be used fairly interchangeably, blue line) and progesterone (black line). The ovaries release a shot of estrogen right before ovulation. It’s literally a symphony of hormones at ovulation – releasing an egg is important! Progesterone is really important because it’s slow buildup in the second part of your cycle is what keeps your endometrium* growing. Progesterone is being released by your corpus luteum, the leftover cells from the follicle the egg was just released from at ovulation. The corpus luteum keeps producing progesterone to build up the lining because it is getting ready for that egg to be fertilized and stay in the uterus to grow into a little baby. If the egg gets fertilized* and implants, other hormones take over for the corpus luteum but we’ll get to that elsewhere. If there is no fertilization/implantation, progesterone, estradiol/estrogen, FSH, and LH levels drop. Eventually, they get to a low enough or critical level that your endometrium sloughs off and you have a period*. Go back to the beginning and repeat. Over. And over. And over. Until you run out of eggs or have some other hormonal changes. But we’ll get to that on another page…
You’re probably not “textbook”
Something that is SUPER important to note about all of this: even though we have this lovely picture out of a science textbook that makes it look all clean and simple, you don’t necessarily ovulate on day 14 (or the traditional halfway point) of your cycle. Even if you do have a 28 day cycle, there is no guarantee that you will ovulate halfway through. You might have a 10 day luteal phase which would mean you ovulate on day 18. That is the single biggest assumption/mistake women make that gets them pregnant before they are ready. Just to make sure I’ll say it again: your cycle might NOT be 28 days long and you might NOT ovulate exactly halfway through. K? To find out when you do ovulate, you should practice Fertility Awareness. FAM should be practiced by ALL women, not just those seeking to avoid/achieve pregnancy.