Finding Your Fertility: A Guide to Period and Fertility Tracking

Katie Crino
Katie Crino
September 13, 2022 · 4 min read Sources Verified
Updated: April 10, 2023

Some women are all too familiar with the phenomenon "baby fever". They are filled with emotion at the sound of a baby's laugh or the sight of tiny shoes. Other women shudder at the thought of having a child, horrified by changing diapers and sacrificing nights out. As a result, most women are trying to either get pregnant or avoid it at all costs.

Whatever side you may fall on, your menstrual cycle can be used as a valuable tool. Your fertility fluctuates depending on the point you are at in your cycle. So, understanding how your own cycle works is key.

In both instances, knowing when you are fertile can help. Avoiding sex during these fertile windows can serve as another line of defense against pregnancy. On the flip side, if you're hoping to start a family, having sex during these fertile windows can increase your chance of getting pregnant, meaning you can finally buy those tiny shoes.

Anna Shvets // Pexels

What is your menstrual cycle?

Most women have a menstrual cycle that lasts 28 days, from the first day of their period to the first day of their next period. Within these 28 days, 3-7 days are menstruation (your period).

Your entire cycle has one large end goal in mind: preparing your body for fertilization and pregnancy. To do this, a woman's body rotates between two phases throughout the 28-day cycle: your follicular and luteal phases. These two phases revolve around menstruation and ovulation.

Follicular Phase

Your follicular phase begins on the first day of menstruation and ends on the last day of ovulation, totaling around 10-16 days long. During this time, your body releases a hormone called follicle stimulating hormone (FSH). This hormone stays true to its name and encourages the ovary to produce a tiny sac called a follicle to hold the immature egg. As this follicle matures, your uterine lining begins to thicken to prepare for pregnancy.

FSH’s role in egg maturation makes it a valuable hormone used in fertility testing. High or low levels of this hormone can indicate health problems like infertility, hormone imbalances, ovarian tumors, turner syndrome, and more. Women generally take this blood test when they are having trouble getting pregnant, have irregular cycles, or have suddenly stopped their period.


To those trying to get pregnant, ovulation is the most crucial event in your menstrual cycle. If you count the days starting from the first day of your period, ovulation will usually fall on days 12-14 if you are on the typical 28-day cycle. Ovulation is the release of the mature egg from the follicle in your ovary to your uterus in preparation for sperm fertilization.

It's important to know that ovulation is when you are most fertile, but it only lasts 12-24 hours. If this time window is tricky to meet, never fear; you are also fertile five days before ovulation and around one to two days after.

Diagram of average menstrual cycle

Luteal Phase

The luteal phase begins at the same time as ovulation and ends before menstruation. This phase is normally 14 days long, meaning any variation in your menstrual cycle usually comes from the follicular phase. During these 14 days, the follicle originally housing your egg begins to transform into a hormone-producing structure. The hormones released by this structure keep the uterus walls thick as your body waits for a fertilized egg.

If, after 14 days, no fertilized egg implants into the uterus lining, your hormone-producing structure withers away, and your menstruation cycle begins.


Diagram of uterus
Nadezhda Moryak // Pexels

As mentioned earlier, your cycle's primary goal is to prepare your body for pregnancy. Therefore, if after 14 days, there's no fertilized egg to develop, your body sheds the unnecessary thickened uterine lining. The blood you see during your period results from this shedding and contains cells from the lining.

Your body continues to shed for the next 3-7 days. After this is done, your body repeats the cycle in hopes of fertilization the next month.

Tracking Fertility

1. Calendar Method

Picture of Guava's Cycle Tracking Feature
Guava's Cycle Tracking Calendar

Tracking the length of your cycle, ovulation, and period is a great way to track your fertility window. In addition, apps like Guava can help you get rid of the mounds of period diaries, calendars, and notebooks.

With Guava, you can easily track your periods to see future period, fertility, and ovulation predictions. You can also set reminders to let you know if your period is running late and when your period or fertility window is coming so you can plan accordingly.

That said, many women don't have regular periods, and therefore, tracking your fertility window with this method probably won’t be reliable. But fear not; there are other ways to predict your fertility window.

2. Discharge Method

Learning to read your discharge is one way. Keeping a diary of discharge texture, color, and smell for each day of the month can help you discern discharge during your fertility window vs. other phases. During your fertility window, mucus that is said to resemble egg whites is the consistency you should be looking for, i.e., stretchy, clear, and wet. However, this method can prove difficult and should be discussed with a provider so they can help you better understand your different discharges.

3. Basal Body Temperature

Your basal body temperature (your body temperature at rest) can also be used to predict ovulating patterns. To do this, you must measure your temperature as soon as you wake up using a basal thermometer (a more sensitive thermometer). A slight temperature rise (half a degree of Fahrenheit) is seen directly after ovulation. Therefore, recording and tracking your basal body temperature patterns can help you later predict when ovulation will occur.

4. Ovulation Predictor Kit

RODNAE Productions // Pexels

An ovulation predictor kit is helpful for testing for ovulation as well. This urine test indicates the presence or absence of a specific hormone. If the hormone is present, it means you will begin ovulating within 24 hours.


Tracking your menstrual cycle is a great way to monitor your health and ensure all is normal down under. Highly irregular or absent periods can be signs of pregnancy, hormone issues, and even cancer. Important irregularities to look for could be your period suddenly becoming irregular (and you're under 45), menstrual cycles that are shorter than 21 days or longer than 35, a period longer than 7 days, and large differences in the length between your menstrual cycles.

These irregularities can also be a result of excessive stress, exercise, or weight loss/gain. Regardless, you should always talk to your doctor if you are experiencing irregular periods.

So, whether you are dreading or dreaming of getting pregnant, remember your menstrual cycle can be a valuable tool in fertility tracking and overall health monitoring if you take the time to understand it.

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