Understanding the Menstrual Cycle

Welcome to Module One: Meet Your Hormones — understanding the key players in your cycle. I feel like this is the foundation we need to understand what's going on in our menstrual cycle. There are about four or five key hormones to understand during this time and what happens when they go a little bit out of balance. I'm going to start off with the first part of this module, really understanding the menstrual cycle, what happens during this time, and who the key players are. Because if you understand what's happening during the menstrual cycle, how it works, and what each hormone does, a lot of the symptoms will make more sense, especially when you know when they appear at different times in your cycle. So let's start with Menstrual Health 101 — what happens during the menstrual cycle. The menstrual cycle is the cyclical building of the uterine lining and shedding of the uterine lining if fertilization hasn’t occurred. It exists to help us procreate during our fertile years, but it’s also really important to understand even if we don’t want to have children or our childbearing years are done, because the hormones are still at play. A lot of our symptoms are dictated by these hormonal fluctuations. I’ve got some notes here, so if I look down, it’s just to make sure I don’t forget anything. The menstrual cycle is usually divided into three phases: the follicular phase, ovulation, and the luteal phase. After that, menstruation starts the cycle over again. The first phase is the follicular phase. As the name suggests, this is when the follicles in the ovaries are maturing. Usually one dominant follicle is selected to be the one that’s ovulated in that cycle. The follicular phase usually lasts about 14 days, depending on the woman’s cycle length. One of the main hormones here is FSH, follicle-stimulating hormone, which, as the name suggests, stimulates the follicles in the ovaries to mature. We also have estrogen during this phase, which is the hormone of growth and proliferation. Its main function during this time is to build the uterine lining. After menstruation, when everything has been shed, estrogen begins to rebuild that lining in preparation for ovulation and potential implantation. So estrogen is building the uterine lining, while follicle-stimulating hormone is maturing the follicles. Just before ovulation, we have a surge in a couple of hormones — luteinizing hormone (LH) and estrogen. LH is the hormone tested in ovulation predictor sticks. That LH surge happens just before ovulation and indicates that ovulation is near. Around the same time, there’s also a surge in estrogen, which, in addition to building the uterine lining, changes cervical mucus, making it more egg-white-like and hospitable for sperm. That’s when you might notice more slippery or egg-white secretions. As we get closer to ovulation, we also see a surge in testosterone, our hormone of action. It’s what gives us that little extra spark or motivation, and it’s the hormone that makes you feel a little more frisky or energized — nature’s way of nudging reproduction. All three — LH, estrogen, and testosterone — peak just before ovulation. Then the dominant follicle releases the egg, and that’s ovulation, the star of the show and the whole purpose of the menstrual cycle. What’s left behind of that follicle becomes the corpus luteum, which starts producing another hormone called progesterone. After ovulation, we enter the luteal phase, named after the corpus luteum. Progesterone, as its name suggests (pro-gestation), is the hormone that maintains a pregnancy if fertilization occurs. During the menstrual cycle, progesterone helps maintain the uterine lining, oxygenates it so an embryo can implant, and prevents the uterus from contracting. It’s a smooth muscle relaxant and a very calming and sedating hormone. Progesterone is also a pro-thyroid, metabolic hormone — which is why your body temperature rises slightly in the second half of your cycle. If you track basal body temperature, you’ll see that shift. Because metabolism increases, you may also notice feeling hungrier or craving more carbohydrates. Progesterone is anti-anxiety and helps with relaxation and sleep. You might also feel a bit more introverted in this second half of your cycle. If fertilization doesn’t occur, progesterone and other hormones dip after about 14 days, and the uterine lining sheds. This is your period, and the cycle begins again. The length of the menstrual cycle can vary between 25 to 30 days. The follicular phase can vary, but the luteal phase is quite consistent — about 14 days. It takes around seven days for progesterone to peak, and another seven for it to decline if fertilization hasn’t happened. If your luteal phase is shorter than 10 days, that can indicate low progesterone or luteal phase dysfunction. The average cycle length is about 28 days, but anywhere between 25 and 30 is normal. A healthy menstrual cycle should be mostly asymptomatic, meaning it shouldn’t come with excessive warning signs, pain, or discomfort. Ideally, your period should start without too many symptoms beforehand — no extreme PMS, minimal cramping, no heavy clotting or spotting before bleeding starts. A healthy flow should be bright red, moderate (not too heavy, not too light), with little to no pain. If you’re experiencing significant symptoms like cramps, pain, insomnia, or strong mood changes — particularly in the second half of the cycle — it could point to a hormonal imbalance, often involving progesterone. In the second half of the cycle, progesterone should be dominant, while FSH, LH, estrogen, and testosterone dip after their ovulatory peaks. Estrogen does have a small secondary rise, but progesterone should lead. When that balance is off, symptoms arise. So that’s Menstrual Cycle 101 — the foundation. Next, we’ll dive deeper into the key players, especially estrogen and progesterone, and look more closely at what they do and how they affect how you feel.