When Do You Ovulate: Explaining the Ovulation Cycle

Whether you’re trying to get pregnant or trying hard not to get pregnant, you’re probably wondering when you ovulate. It’s a critical piece of information when it comes to baby-making. Despite that, it can be pretty tough to figure out.

There are now a lot more options available for tracking ovulation at home. Most of them can help to some extent, but some are much more accurate than others.

We’ll take a look at ovulation symptoms, how your ovulation cycle works, and more.

Key Takeaways

Usually, women ovulate about halfway through their menstrual cycle.
Fertility is at its peak in the five days leading up to ovulation.
The typical menstrual cycle is considered to be 28 days, but the length will often vary.
Checking the consistency of cervical mucus may be the cheapest and most effective method of gauging ovulation.
Fertility calendars and apps aren’t a reliable way to track fertility.
You can get pregnant at any point in your menstrual cycle, even during your period.

What Is Ovulation?

Ovulation is a part of a woman’s menstrual cycle, during which an egg is released from the ovaries. The egg then moves down the fallopian tubes to the uterus. At some point during the egg’s trip, it may be fertilized by a sperm. Either way, the egg implants itself in the lining of the uterus.

If it has been fertilized, the egg will develop into a fetus. If not, during the menstrual period, it will be flushed from the body along with the rest of the uterine lining.

Or rather, that’s how ovulation would play out ideally. Lots of factors can interrupt that process or cause irregular cycles. Examples include genetics, medical conditions like polycystic ovary syndrome (PCOS), or obesity, as well as smoking, alcohol use, and some medications.

Menstrual Cycle

Obviously, ovulation is one step in the menstrual cycle. The average menstrual cycle is usually thought to be around 28 or 30 days long [1]. It’s considered to start the first day of period bleeding and end on the day the next period begins.

While 28 days is considered the average, from cycle to cycle can take anything from 24 to 38 days and still be considered typical.

The menstrual cycle consists of two general phases and ovulation:

Follicular phase—an egg is prepped for release.
Ovulation—between the two phases.
Luteinizing phase—The egg implants in the uterine lining and either develops or is discarded.

The follicular phase is named for the small cells that develop into an egg, ready to be released, called follicles. After receiving signals from the brain, in the form of follicle-stimulating hormone and luteinizing hormone, the follicles began to grow and separate.

Several follicles might grow, but usually, only one will develop into a mature egg that is released during ovulation. Once an egg is released, it begins to move down the fallopian tube. This begins the luteinizing phase.

During this second phase, the uterine lining is prepared to receive the egg. Either the egg is fertilized and develops further into a fetus, or it is discarded with the lining of the uterus. It’s this lining that forms period ‘bleeding’, rather than actual blood.

The follicular phase may actually begin before period bleeding is completely finished, already preparing the next egg for ovulation.

Ovulation Cycle: When Does Ovulation Occur?

Outlined above is a fairly basic understanding of how ovulation works. In reality, ovulation and a woman’s monthly cycle are actually quite complex. While a monthly cycle is usually considered to be about 28 days, most women will find their cycles vary in length.

Some women even experience very irregular cycles. Conditions like PCOS might cause spotting or even bleeding more days than not. That means that, while the average or ideal cycle is the one most often described, any specific woman may find her schedule is somewhat different.

Ovulation occurs about halfway through a cycle, between days 10 and 22 of your cycle [2]. The levels of estrogen and other hormones rise until the release of an egg is triggered. The egg moves from the ovary to travel down the fallopian tube.

After the egg is released, a woman’s body begins the luteal phase of their cycle. The egg moves into the fallopian tube and may be fertilized or may end up being expelled with the uterine lining.

Some forms of non-hormonal birth control, like the fertility awareness method, depend on tracking the progress of your cycle. The fact that cycles aren’t reliably regular means that they are less effective. A more reliable method may be to look for physical signs of ovulation.

What Days of Your Cycle Do You Ovulate?

As we’ve mentioned, ovulation occurs about halfway through the average human menstrual cycle. However, when most people ask this question, they are really asking either how they can get pregnant or avoid pregnancy. The six days prior to ovulation are the fertile window. The odds increase until they peak on the last three days, including ovulation day.

That means the most fertile days might be just a few days after the end of the menstrual period. After ovulation, the chances fall, with the chances of pregnancy during period bleeding being the lowest.

However, since not everyone always follows the average cycle, figuring out the fertile window can be tough. Someone might have a naturally short menstrual cycle or a naturally longer one. The best method of determining the fertile window is by looking for physical signs of ovulation.

How Do You Know If You Are Ovulating?

A doctor might use a blood test or an ultrasound to discover if you are ovulating, but those methods aren’t available all the time. Fortunately, there are a few over-the-counter methods of gauging when the fertile window opens.

Basal Body Temperature

Your basal body temperature is your temperature at rest. A small increase in that temperature can signal when a woman ovulates. In practice, this method ends up being difficult to use and is only accurate about 22% of the time. It’s difficult to tell the rise in temperature signaling ovulation from normal variation [3].

There are some products that can help increase the accuracy, such as a basal body thermometer. This ovulation test is usually combined with others.

Luteinizing Hormone Testing

These often come packaged very similarly to a pregnancy test. Rather than testing for a fertilized egg, however, it is testing for the hormones that are released when a mature egg is released [4].

The menstrual cycle has two overlapping phases, the first being the follicular phase when an egg is prepped for release. Ovulation occurs in between the two phases. The last is the luteal phase, when hormones are released to prepare the way as the egg travels to the uterus.

Luteinizing hormone levels can be detected in urine, like pregnancy hormones. Manufacturers claim their accuracy rate for detecting the fertile window is 95% or better

Cervical Fluid

Cervical fluid is usually better described as cervical mucus, thick enough to act as a barrier. After ovulating, however, a woman’s body changes in a few ways to become more receptive to sperm. Cervical mucus can become thinner and more fluid at that point.

As yet, ovulation prediction kits can’t analyze cervical mucus, it isn’t really necessary. A woman can examine the cervical fluid that is collected with a finger and assess its thickness. As signs of ovulation go, it’s cheap and surprisingly effective, even for women who experience irregular ovulation [5].

It doesn’t cost anything, and it can be as much as 95% effective in detecting ovulation [6]. Women attempting to prevent pregnancy were successful over 98% of the time. This method is commonly combined with measuring basal body temperature.

Fertility Calendar

Fertility apps are a relatively new method of tracking fertility, though they are really just a high-tech version of the fertility awareness method. The user enters information about her menstrual cycle, including when her menstrual cycle begins and when her next period occurs.

Using that information, the calendar can begin making calculations to predict fertility, the next day period bleeding will start, and so forth. More sophisticated apps may combine that information with body temperature readings or other observations.

Generally, these methods aren’t considered very reliable [7]. They are based on the average cycle, but an average woman’s cycle length can vary. Many women experience irregular periods or ovulate early due to a shorter cycle length. Generally, it will work better for someone with a regular cycle.

Ovulation Calculator

Ovulation calculators, particularly online calculators, can offer a rough idea of when your next fertile days will be. It is only a rough idea, however, as many factors can throw off regular menstrual cycles, and even regular cycles vary.

How Do I Calculate My Ovulation Date?

There are a number of ways to calculate ovulation, some more complicated than others. Some fertility calendars require you to enter a lot of variables but might have a more accurate estimate for the date of ovulation.

A simple ovulation calculator just requires a little basic math. If you’re on a fairly regular 28-day cycle, you can subtract 15 days from the date you expect your next period to start. For example, on a 28-day cycle, if you expect your next period to start on May 16th, your ovulation day is going to be around May 1st.

Another method you can do by hand is a little more complicated. You’ll need to know the length of the longest and shortest cycles you’ve recorded [8]. Taking it step-by-step:

Divide your shortest cycle’s length by 2.
Subtract 5 from that result.

That gives you the number of days after your next menstrual cycle starts when you are at your most fertile.

To figure out how many days you will be most fertile, step-by-step:

From the longest cycle, subtract the shortest cycle.
Add 8 to the result.

These sorts of calculations are best used when also looking for physical signs of ovulation.

Do Ovulation Predictor Kits Work?

Most ovulation predictor kits (OPK) center around a luteinizing hormone test, which measures certain hormones associated with ovulation. As we’ve mentioned, these are usually similar to a pregnancy test, requiring urine to analyze.

However, as might have become clear, predicting ovulation can be a pretty complicated business. While some of the least expensive options just offer test strips, there are also ovulation test kits out there that combine hormone testing with other methods of predicting ovulation.

More expensive and elaborate OPKs may come with a digital monitor or a calendar app for your smartphone. The apps usually involve some sort of calendar, incorporating the information that comes from the test that comes with it.

Generally speaking, using an ovulation predictor kit can improve your chances of being pregnant. For women with shorter cycles or irregular menstrual cycles, they may help reduce some confusion. Their use may improve the chance of getting pregnant only slightly, however, and there are other options available that may also help.

Using OPKs did lower the amount of stress and uncertainty hopeful parents felt, a factor which by itself may justify their use [9].

FAQ

When Do You Ovulate After Your Period?

Normally, women ovulate about halfway through their menstrual cycle. The cycle begins on the first day of a period and ends the day the next period begins. To get a rough date of ovulation, figure out the next day you expect a period to begin. The day about halfway along is an estimate for your ovulation date.

An average cycle is about 28 days, though they can often vary. As a result, while it’s possible to make a guess at when your next period starts, it’s not considered a reliable guess.

Do You Ovulate While Pregnant?

Generally, no, women do not ovulate during pregnancy. Ovulation, along with the other stages of the menstrual cycle, all are governed by hormones. During pregnancy, however, all the hormones are telling a woman’s body to get ready for birth. The signals to release the egg, change the consistency of cervical mucus, and all the rest never get sent.

With that said, it has been known to happen. Very rarely, a second egg is ovulated and fertilized during sexual intercourse. The woman would then have two fetuses at different stages of development in her uterus [10].

It’s rare enough that it’s difficult to study. For the most part, the chance of getting pregnant again during early pregnancy are pretty close to zero.

When Are You Ovulating the Most?

Not to be pedantic, but actually, ovulation is when an egg is released and usually only occurs once per cycle. When most people talk about ovulating, they mean the changes that occur in a woman’s body to increase the chances of an egg being fertilized and safely implanted in the uterus.

Ovulation usually occurs about halfway through a menstrual cycle. The most fertile time of the cycle are the six days ending in the day of ovulation. That means that the best time to get pregnant may just be a few days after your period bleeding ends. If you’re trying to avoid pregnancy, you might want to abstain for those days.

When Are My Most Fertile Days?

Most women are fertile from about five days before ovulation, with the highest chances being the three days leading up to the day of ovulation. If you’re trying to get pregnant, those three days are the best to be active.

If you would rather not get pregnant, avoiding unprotected sex during that period is a good idea. Using protection is a better idea, though outercourse, in which there is no penetration, also has a low chance of getting pregnant.

If you’re not sure how to get birth control, there are many options, including Planned Parenthood.

Can I Get Pregnant 7 Days After My Period?

Yes, it is possible to get pregnant about a week after your last menstrual period. In fact, while your chances of getting pregnant are higher at certain times, it is possible at just about any time.

The menstrual cycle starts when one period starts and ends when the next period starts. Ovulation, when an egg is released to be fertilized, occurs about halfway through the cycle, and women are most fertile three or four days prior to that.

That means that not only can you get pregnant seven days after your period, that is actually pretty close to when you are at your most fertile time. If you want to prevent pregnancy during that period, avoid unprotected sex.

Conclusion

Like many biological processes, it’s hard to predict exactly how ovulation is going to work or when it’s going to happen. That can be frustrating for a lot of reasons. If you’re trying to get pregnant, it’s like trying to hit a moving target. Plus, avoiding pregnancy will never be a sure thing.

When trying to get pregnant, tracking and understanding fertility is hugely helpful and can have a real impact on success. As far as birth control goes, though, you’re better off investing in a box of condoms.

References:

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Wilcox, A. J., Dunson, D., & Baird, D. D. (2000). The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study. BMJ (Clinical research ed.), 321(7271), 1259–1262. https://doi.org/10.1136/bmj.321.7271.1259
Ecochard, Rene, et al. “Self-Identification of the Clinical Fertile Window and the Ovulation Period.” Fertility and Sterility, 24 Feb. 2015, www.fertstert.org/article/S0015-0282(15)00078-3/fulltext.
Holesh, JE, et al. “Physiology, Ovulation.” Europe PMC, 20 July 2017, europepmc.org/article/NBK/nbk441996.
Thijssen, A, et al. “’Fertility Awareness-Based Methods’ and Subfertility: a Systematic Review.” Facts, Views & Vision in ObGyn, Universa Press, 2014, www.ncbi.nlm.nih.gov/pmc/articles/PMC4216977/.
Su, Hsiu-Wei, et al. “Detection of Ovulation, a Review of Currently Available Methods.” American Institute of Chemical Engineers, John Wiley & Sons, Ltd, 16 May 2017, aiche.onlinelibrary.wiley.com/doi/full/10.1002/btm2.10058.
Johnson, Sarah, et al. “Can Apps and Calendar Methods Predict Ovulation with Accuracy?” Taylor & Francis, 10 Apr. 2018, www.tandfonline.com/doi/full/10.1080/03007995.2018.1475348.
James, William H. “Cycle Day of Ovulation: Journal of Biosocial Science.” Cambridge Core, Cambridge University Press, 31 July 2008, www.cambridge.org/core/journals/journal-of-biosocial-science/article/abs/cycle-day-of-ovulation/3F3202A44BB3BF01BE12EEE1EC2CC294.
Yeh, Ping Teresa, et al. “Should Home-Based Ovulation Predictor Kits Be Offered as an Additional Approach for Fertility Management for Women and Couples Desiring Pregnancy? A Systematic Review and Meta-Analysis.” BMJ Global Health, BMJ Specialist Journals, 1 Apr. 2019, gh.bmj.com/content/4/2/e001403.full.
Omo-Aghoja, Lawrence. “(PDF) Superfetation in Humans – Myth or Reality?” ResearchGate, Unknown, 1 June 2017, www.researchgate.net/publication/322275983_Superfetation_in_Humans_-_Myth_or_Reality.