4 Phases of the Menstrual Cycle and Hormones
Picture us sitting at a cozy coffee shop, peppermint mochas in hand, chatting about all things menstrual cycle. You’ve got questions, and I’ve got answers. I’m going to walk you through everything I think you should know about the 4 phases of the menstrual cycle and hormones associated with each one: basically, everything you should have learned in your high school health class but didn’t.
There are four phases in your menstrual cycle:
The menstrual phase (when you bleed)
The follicular phase (when your body matures a follicle to release or hatch an egg)
Ovulation (when that egg is released)
The luteal phase (the second half of your cycle).
If pregnancy doesn’t happen, the cycle starts all over again.
Your menstrual cycle is a reflection of your overall health. So many different systems in your body have to work together to create a regular, rhythmic, and predictable cycle that is not painful. When one of those systems isn’t functioning properly, your cycle often gives you clues. By paying attention to your period and the patterns throughout your cycle, you can start to uncover where things might be off.
Unfortunately, when something is off with a woman’s cycle, the default answer from many doctors is to prescribe oral birth control to “fix” it. But here’s the truth, that doesn’t actually fix anything. It just masks the underlying issue.
My goal is to help women learn how to track their cycles so they can take real data to a provider who actually listens, cares, and knows how to address the root cause. Because when things like PCOS, endometriosis, or thyroid dysfunction go untreated in your teens or early twenties, they don’t magically disappear. They usually just show up later, typically right when you’re ready to start trying to conceive.
In this blog, we’ll go over each of the 4 phases of the menstrual cycle and the hormones that rise and fall through each one: menstruation, the follicular phase, ovulation, and the luteal phase. You’ll learn what’s normal, what’s not, and when it might be time to seek help if something feels off.
1. The Menstrual Phase: The Reset
The menstrual phase is when you’re actually bleeding. Everyone loves to talk about how your hormones are “all over the place” during your period, but in reality, both estrogen and progesterone are at their lowest.
The average amount of blood loss is around 50 milliliters, but anywhere from 25 to 80 mL is considered normal. That’s about three tablespoons. For reference, a regular soaked pad or tampon holds about 5 mL, and a super tampon holds 10 mL. So a typical 50 mL period would be the equivalent of about 10 soaked regular tampons or 5 soaked super tampons.
Your period should last 2 to 7 days, with most women bleeding around 3 to 5. Your first heavy day counts as day 1 of your cycle. When we talk about your menstrual cycle, we’re measuring from day 1 of bleeding to the next day 1 of bleeding, and that total should fall somewhere between 21 and 35 days.
As for color, it can range from bright red to brown. The darker color happens when blood has been exposed to air, for example, if a pad has been on for a while. A few small clots about the size of a dime are totally normal, but larger clots can sometimes signal uterine fibroids and are worth mentioning to your provider.
Menstrual fluid itself is a mix of blood, cervical mucus, vaginal secretions, and a little bit of uterine lining, all part of your body’s natural monthly reset.
2. The Follicular Phase: The Growth Phase
The follicular phase is well named because this is when your body is busy producing follicles. It actually takes about 100 days for your follicles to mature from their dormant state all the way to ovulation. The follicular phase itself usually lasts anywhere from 21 to 35 days.
Each cycle typically starts with six to eight follicles, but only one becomes the dominant follicle, the one that will eventually release an egg. A follicle is a fluid filled sac that holds one egg, and it’s also the part of your ovary that produces estrogen, progesterone, and testosterone.
Toward the end of this phase, the hypothalamus releases gonadotropin releasing hormone (GnRH), which signals the pituitary gland to release follicle stimulating hormone (FSH). FSH encourages the ovarian follicles to grow. Once one follicle becomes dominant, it starts producing more estrogen, which then triggers a luteinizing hormone (LH) spike, and that LH surge is what tells your body it’s time to ovulate.
About 24 to 36 hours after the LH surge, the dominant follicle releases its egg. The egg is then swept up by the end of the fallopian tube (the fimbriae) where it can be fertilized if sperm are present.
During this phase, your developing follicles produce estradiol, your “happy hormone.” Estradiol benefits nearly every part of your body, your bones, muscles, brain, heart, skin, metabolism, and even sleep. It also helps prevent insulin resistance and thickens your uterine lining to prepare for a potential implantation after ovulation. Plus, estradiol is what makes your cervical mucus turn into that stretchy, egg white consistency that signals your fertile window is approaching.
3. The Ovulatory Phase: The Fertile Window
And now we’re at ovulation, the main event. One follicle becomes the dominant, winning follicle, and after that LH spike, it ruptures (or as I like to say, hatches) and releases the egg. The actual release of the egg is ovulation, and the event itself only takes a few minutes.
Some women notice lower abdominal cramping or what’s called mittelschmerz, that’s just a fancy term for middle pain. It’s often one sided but can sometimes happen on both sides. Ovulation is all or nothing, it either happens or it doesn’t. After ovulation, the egg is either fertilized or not, meaning you’re either pregnant or you’re not.
On average, women ovulate around day 14, but only about 20 percent of women actually ovulate on that day. Remember, that’s just an average, not the rule.
If you want to dive deeper into how to know if you’re ovulating, you can check out this blog post here. There are four main ways to track ovulation, and it’s usually most accurate when you use a combination of them:
Cervical mucus – look for that egg white consistency
Basal body temperature – a slight rise confirms ovulation after it happens
Ovulation predictor kits – detect your LH surge
Ovulation cramping – that telltale twinge mid cycle
After ovulation, your egg is swept up by the fimbriae, the ends of your fallopian tubes, where it can potentially be fertilized.
4. The Luteal Phase: The Wind Down
After ovulation, you either get pregnant or you don’t, and that’s when the luteal phase begins. The follicle that released your egg transforms into the corpus luteum, which is a temporary endocrine gland. Its lifespan is about 10 to 16 days, so within that window, you’ll either start your next period or be pregnant. There’s no third option.
The corpus luteum produces progesterone, which is your calming hormone. Progesterone reduces inflammation, builds muscle, promotes sleep, protects your heart, supports the nervous system, and helps your body better handle stress.
The health of the corpus luteum can be affected by inflammation, thyroid dysfunction, insulin resistance, or nutrient deficiencies, especially in magnesium, B vitamins, vitamin D, iodine, zinc, and selenium.
Progesterone’s main job is to support a potential pregnancy (hence the name pro-gestation), but it does much more than that. It also helps thin your uterine lining, which can lead to lighter periods. So if you’re dealing with heavy bleeding, one thing to consider is whether you’re actually ovulating, because if you’re not, you’re not making progesterone, and your lining keeps thickening.
Progesterone also has a stimulating effect on the thyroid, which is why your basal body temperature rises after ovulation, that’s one of the easiest ways to confirm ovulation. If pregnancy doesn’t occur, the corpus luteum starts to shrink, progesterone levels drop, and that hormonal shift tells your uterus it’s time to shed its lining and begin a new cycle.
How to Work With Your Hormones
So, to wrap it all up, your menstrual cycle is designed to work in rhythm. Each of the 4 phases of the menstrual cycle and hormones has a specific job, and when everything’s running smoothly, your body moves through those phases like clockwork.
Your hormones influence so much more than just your period, they affect your mood, metabolism, energy, and fertility. When you start paying attention to how you feel in each phase, you can actually begin to work with your hormones instead of fighting against them.
Start by tracking your cycle. Note your bleeding days, cervical mucus, basal body temperature, and any physical or emotional changes. Over time, you’ll begin to see patterns that help you understand what your body’s trying to tell you.
And if something feels off, that’s your body’s way of asking you to pay attention.
If you’re experiencing an abnormal cycle and want help, I am currently accepting new clients for one-on-one care. I see patients both virtually and in person in Sulphur Springs, Texas and Rockwall, Texas. You can fill out a form [here] and someone from our team will reach out to schedule your appointment.
If you’re preparing to start trying to conceive and want to better understand your ovulation and overall fertility, I highly recommend our 30-day email series, Fertility Foundations, created by me and my husband, who is a pharmacist. This series walks you through everything we believe you should know before trying to conceive—everything you weren’t taught in your high school health class.
You can read more about Fertility Foundations [here].
Next on your reading list:
How to Know if You’re Ovulating
Tips for Getting Pregnant at 30-35
