Although hormones play an important role in reproductive health, they have other effects on the body and mind. And since our hormones are always changing—rising and falling based on where we are in our cycles—sometimes we get a notification of these changes in the form of certain signs or symptoms. When we experience hormonal symptoms, it’s likely due to the relative differences in hormone levels. (And of course, you can also experience symptoms if you’re undergoing treatment doses of these hormones.)
Contributing to your menstrual cycle, there are four key hormones (estrogen, progesterone, luteinizing hormone and follicle stimulating hormone), each with their own little rollercoaster ride that gets repeated every 28-ish days. Not everyone’s full ride will be exactly 28-days long—it could be a few days shorter or longer—but the synchronized pattern of hormones rising and falling will be similar. It’s no surprise we call it a cycle. Some of these changes are normal and healthy, like the estrogen-associated cervical mucus. Others might be noticed when hormone levels are too high or low—like mood swings before your period. If any symptoms are feeling particularly problematic, speak with your doctor about ways to manage your cycling hormones.
Menstrual cycle phases
Your menstrual cycle is made up of two phases: the follicular phase, which starts with menstruation and ends with ovulation, and the luteal phase which takes us from ovulation to the day before our next menstrual period.
Follicular Phase
There is a very small build of hormones during menstruation, like the calm before the storm. Just before menstruation, follicle stimulating hormone (FSH) is actively recruiting follicles. The stimulated follicles grow granulosa cells which produce estrogen, and as the menstrual flow is complete, the estrogen levels start rising (which tells FSH to cool its jets, known as negative feedback) and continues its climb until it reaches the first and very high peak of the rollercoaster, before dropping.
Pre-ovulation
When estrogen peaks high enough, it signals LH to surge (known as positive feedback). This LH surge is what causes ovulation, the release and maturation of the egg from the surrounding follicle cells.
Luteal Phase
After the egg is ovulated, the remaining shell of the dominant follicle cells transform into the corpus luteum and the granulosa cells that once were only producing estrogen now start to also produce progesterone, which continues to build in a wider and more gradual peak. This also causes estrogen to have a small comeback at the same time, like progesterone’s little buddy, rising mid-luteal phase (but not as high or dramatically as in the follicular phase) to support endometrial lining health. These two hormones prep the uterus for implantation having it ready by about seven to nine days post-ovulation. Once that’s achieved, the corpus luteum runs out of juice and starts to break down (around nine to 11 days post-ovulation), meaning progesterone and estrogen levels take a dive if there is no pregnancy.
Menstruation
The dropping off of estrogen, but especially progesterone, triggers the uterus to shed its lining. Meanwhile FSH is already starting to recruit the next cohort of follicles.
What Is a Normal Menstrual Cycle and Period? →
Follicle Stimulating Hormone (FSH)
FSH does exactly as the name states: it stimulates the follicles. FSH rises during the menstrual period (it starts just before your period begins when progesterone is taking a dive)—causing the recruitment of the next group of follicles. In response to FSH, each follicle starts producing estrogen. As estrogen levels rise, it shuts down FSH (like a negative feedback) since we don't need to keep recruiting follicles or make them all grow.
FSH as a fertility treatment
FSH analogues are one type of hormone drug used in in-vitro fertilization (IVF) and egg freezing. Since FSH recruits follicles and helps them during their initial growth stages, giving the body more FSH will help the ovaries recruit more follicles and help more of them to grow. With FSH medications, side effects are generally related to the downstream effects of multiple follicles being recruited—larger ovaries and higher estrogen levels. Other side effects are generally mild and short lasting, but can include headaches, breast tenderness, and abdominal discomfort.
Estrogen
In the early follicular phase, each tiny follicle starts to produce a little bit of estrogen which help to stimulate its growth. The follicle that responds the best is the “dominant follicle,” and it’s usually selected by cycle day seven. Once that (typically) one follicle begins to stand out, it shuts down the growth of all the other follicles around it and they are discarded.
The dominant follicle produces lots of estrogen causing the rising estrogen levels at the end of the follicular phase, peaking just before ovulation. This high estrogen peak represents an egg that is fully mature and ready to be ovulated.
Estrogen takes a short break just after ovulation (declining a bit) because the dominant follicle bursts, and with it many of the granulosa cells that produced estrogen are sloughed off. But estrogen has a small comeback during the luteal phase as progesterone rises, (but not as high or dramatically as in the follicular phase) to support endometrial lining health.
What you might notice during the ovulation window:
- Cervical mucus: Rising estrogen levels open up certain pockets in the cervix called cervical crypts. These release cervical mucus that upon wiping you might notice as slippery, lubricative, clear and stretchy, looking similar to raw egg-whites. This cervical mucus is your fertile fluid since it provides an environment to allow sperm to survive longer. You’ll notice this mucus disappear after a few days, as estrogen levels decline around ovulation.
- Increased Libido: Higher estrogen levels can increase sex drive, which is convenient during the fertile window (the days before ovulation) if you’re TTC. (Testosterone is also heightened during this time, contributing to that increased arousal.)
Low luteal progesterone or estrogen treatment
If you’re undergoing fertility treatments, estrogen medications (like the tablet, patch or vaginal versions) can be used throughout your embryo transfer cycle to help support lining thickening and receptivity. But anytime we jack up our estrogen levels, there’s a possibility of it causing symptoms.
What you might notice with estrogen medications:
- Headaches or migraines: This is more common in those who notice hormonal migraines, or those that come on before the start of a menstrual period.
- Constipation
- Weight gain and/or water retention
- Breast tenderness and/or swelling
- Irritability and/or rage-type mood premenstrually
- Feeling anxious or depressed
Luteinizing Hormone (LH)
The estrogen peak in the follicular phase causes luteinizing hormone (LH) to surge. Think of LH like a drop-zone ride: it surges fast and high and then will plummet again all within about two days. That LH surge, which happens about 36 hours before ovulation, is the trigger and tells the ovary to release the egg by rupturing the dominant follicle.
What you might notice
- Mittelschmerz: The word “mittelschmerz” translates to “middle pain,” and is often felt like a light cramping, aching or pressure on one side (whichever ovary is producing the dominant follicle) of the lower abdomen. This sensation correlates with the LH peak, which can also help with the timing of intercourse when TTC.
- Energy: It’s not uncommon to have much more energy at this time in your cycle and for your mood to be at its best. You’re about to ovulate—your body wants you feeling happy and energized for potential baby-making.
Progesterone
After the egg has been released, the remaining shell of follicular cells turns into the corpus luteum which produces and releases the progesterone that preps the uterus for a potential embryo implantation. Progesterone levels rise after ovulation in a wider and more gradual peak.
Learn More about hCG →
If the egg is fertilized and develops into a viable embryo that implants in the uterus, the cells that will become the placenta will release the pregnancy hormone hCG and keep the corpus luteum alive—otherwise it’s on a self destruction timer. If the progesterone levels fall this tells the uterus to shed the lining, start fresh, and recruit a new group of ovarian follicles to try again the next cycle.
What you might notice with progesterone medications or with higher progesterone and lower estrogen:
- Bloating and constipation (due to your bowels slowing down)
- Breast swelling or tenderness
- Weepiness
Keep in mind that no single hormone acts on its own—it’s affected by the presence and concentration of the other hormones. So it’s also possible to have a mix of PMS symptoms, like being weepy and rage-y at the same time (fun!). It’s a good idea to keep track of your symptoms in a calendar so you can better understand when in the cycle they occur or if there’s a clear pattern over several cycles. If you’re concerned about any symptoms that you’re having, speak with your healthcare practitioner.
