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Know Your Menstrual Cycle Phases

Written by:, PhD, Founder and Inventor of the Proov test — the first and only FDA-cleared test to confirm successful ovulation at home.

If you’re trying to get pregnant, especially for the first time, you may quickly realize there’s a lot you didn’t know! For instance, did you know your menstrual cycle (which lasts from the start of one period to the start of the next) has phases, and that understanding these phases can be key to getting (and staying) pregnant? 

While the science of our menstrual cycles isn’t exactly broadcast far and wide, we’ve got you covered. Read on to learn all about what’s going on behind the scenes and making it possible for you to get pregnant! 

What is the menstrual cycle and why is it important?

Let’s start with the basics. The menstrual cycle is the natural progression your body takes from having a period (menstruation), preparing to ovulate, ovulating, and preparing for either pregnancy or another period. It’s called a cycle because that happens over and over again throughout your fertile years. 

It’s important to note that even though it’s called the “menstrual” cycle, it’s about so much more than menstruation. While your period is of course the most noticeable part of the cycle, it’s really only about a quarter (or even less) of the cycle, and if you’re trying to get pregnant, your period is probably the least important part too! 

Your menstrual cycle, and understanding it, are important for a few reasons. One is that if you’re “cycling,” it means that you’re likely ovulating, which is critical for pregnancy! You can’t get pregnant if ovulation doesn’t occur, and you can’t have ovulation without a menstrual cycle. On the flip side, understanding the timing of your menstrual cycle and when to test your hormones can help you get pregnant faster! 

Another important reason to care about your menstrual cycle is that it’s a sign of overall health. If your body isn’t healthy–maybe you’re undernourished, or overexercising, or chronically stressed–your menstrual cycle often becomes irregular or even missing entirely. If that’s the case, you can’t get pregnant, and your body likely needs to rest, recover, and be properly nourished. 

How long is a normal menstrual cycle? 

First of all, by now you know that since your cycle encompasses everything that happens from one period to the next, the length of a cycle is the length of time between periods (from the start of one to the day right before the start of the next). While a lot of apps, social media, and other sources might try to tell you you’re supposed to have a 28-day cycle (and you certainly may), that’s outdated and not always the case! 

Studies have shown that regular menstrual cycles are anywhere from 24 to 36 days, and you may have some variation in length from cycle to cycle (ideally, no more than a few days). So if your cycles are falling anywhere in there, that’s a good indicator that things are at least on an okay foundation. There’s a lot more that goes into it than just length, though, and that’s where the different phases come in! 

Menstrual Cycle Phases

Menstrual Phase

It may sound redundant to say there’s a menstrual phase of your menstrual cycle, and that’s because the menstrual cycle was just named for the most easily noticed part of the cycle–menstruation. 

During this phase, which should last between 2 and 7 days, your uterine lining sheds and, of course, this results in your period. We refer to the first day of your period as cycle day 1, and during this time, your overall hormonal activity is pretty low. Your body is just shedding the lining from last cycle and preparing for a new one! 

Follicular Phase

During the follicular phase, though, things really start to get moving and your body prepares for the release of an egg. In the follicular phase, your ovaries are exposed to the hormone FSH (follicle stimulating hormone), and begin to prepare several follicles. Estrogen will begin to rise, and you may start experiencing symptoms like watery or moist cervical mucus/vaginal discharge

It can vary from person to person and even cycle to cycle, but your follicular phase might actually overlap with menstruation, especially if your period tends to be longer. 

Ovulatory Phase

Once estrogen levels are high enough, it’s time for the main event of the cycle-ovulation, or releasing the egg! If you’re trying to get pregnant, this is one of the phases you should pay the most attention to, because this is the time that sperm can fertilize an egg and lead to conception. 

This phase starts when your estrogen levels are high enough that your cervical mucus is stretchy, clear, and slippery (like raw egg white), and if you’re using at-home hormone testing, you’ll likely detect high estrogen. Sometimes you’ll also hear this phase referred to as the fertile window, or the approximately 6 days that you can actually get pregnant. 

During this phase, it’s a great time for frequent intercourse. After a few days of high estrogen, you’ll experience a surge of luteinizing hormone (LH), which actually triggers the release of the egg from your ovary, indicating your two most fertile days. You can easily test for the LH surge with LH tests (sometimes called ovulation predictor kits), to find the day that your chance of pregnancy is highest. 

Luteal Phase

After ovulation, the egg lives 12-24 hours, and after that, your chances of pregnancy are virtually zero until next cycle. The death of the egg kicks off the luteal phase, the final phase of your menstrual cycle. But even though ovulation is over, the luteal phase is still really important if you’re trying to get pregnant! 

That’s because during the luteal phase, the hormone progesterone rises and is responsible for making your uterus “sticky” to prepare for implantation of a newly fertilized egg. If you don’t have high enough progesterone levels and the luteal phase is too short, the egg might not be able to implant, and even if it was fertilized, you won’t get pregnant (or stay pregnant). 

So during the luteal phase, the most important thing to do is test for successful ovulation. Proov Confirm is the only at-home FDA cleared test for successful ovulation, and these tests work by detecting PdG, the urinary metabolite of progesterone. This will help you understand if pregnancy was likely this cycle, or if you maybe need some extra support from a physician to help you get and stay pregnant. 

If you’re pregnant, or think you are, you can begin testing towards the end of your luteal phase, which lasts approximately two weeks for most people. If you aren’t pregnant, your uterine lining will shed again, kicking off the cycle once more! 

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