Woman with high fertility looking at pregnancy test result

Understanding high fertility vs. peak fertility: key points to know

Medically reviewed on August 1, 2022 by Amy Harris, MS, RN, CNM. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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If you and your partner have decided that it’s time to start a family, you probably want to know when your chances of getting pregnant are at their highest. Or, perhaps, you’ve struggled to get pregnant and want to ensure that you’re trying on the right days to maximize your fertility.

If you’ve started to do a little research on fertility, you’ve probably seen some terms come up over and over: high fertility vs peak fertility. Maybe you aren’t exactly sure what these terms mean and how they can help or harm your chances of becoming pregnant when you’re ready.

We know that the birds and bees aren’t always as simple as the songs say. Ovulation, your menstrual cycle, and fertility can be a little complex at times—that’s why we’ve put together this guide. We’ll walk you through the basics of understanding your high fertility times and when you should try to get pregnant with the greatest likelihood of success.

What does high fertility mean?

Since the term fertility refers to your ability to conceive, then high fertility is a period in which you are more likely to conceive. To help you better understand, let’s review some key terminology related to fertility, including: [1]

  • Menstrual cycle length – The average cycle length falls somewhere between 28 to 35 days. However, some people have a much shorter cycle—as short as 21 days. A cycle begins on the first day of your period and ends when your next period begins. The length of your cycle plays a key role in when you are likely or unlikely to become pregnant after having unprotected sex.
  • Ovulation – Ovulation occurs when an egg is released from your ovaries to be fertilized in the womb (a.k.a. the uterus). Your body releases luteinizing hormone to help control your menstrual cycle. Luteinizing hormone levels quickly increase just before ovulation. During ovulation, progesterone levels also rise to prepare your body for pregnancy. This typically happens between days 12 and 14 of your cycle. However, it can occur earlier or later in the cycle. The timing of ovulation is a key factor in determining when you’ve reached your high fertility period. This period is your most fertile window. There are ovulation test strips that check the LH level in your urine.
  • Egg viability – After ovulation, your egg is only viable for conception for a short period. It must be fertilized by sperm within 24 hours for pregnancy to occur. Although this may make it seem like the conception window is tiny, there are other factors at play. For example, sperm can live for up to five days in your body. This means having unprotected sexual intercourse up to five days before you ovulate can still lead to pregnancy. If the egg is fertilized, the fertilized egg travels to the uterus and becomes a growing cluster of cells called a blastocyst.

These components define your high fertility period during each of your cycles.

When does high fertility occur, and how long does it last?

The beginning of high fertility is referred to as the “onset of the fertility window.” [3] This occurs about five days before ovulation. During this stretch, your fertility levels are high. This is because sperm can live in your body for up to five days. [4] Suppose you have unprotected sexual intercourse five days before ovulation. In that case, there’s a good possibility that live sperm will still be active in your body and able to fertilize the egg released during ovulation.

High fertility lasts from five days before ovulation until the beginning of peak fertility.

What does peak fertility mean?

Peak fertility can be defined in two ways:

  • The age at which you’re most fertile
  • The days during your cycle in which you are most likely to conceive if you have unprotected sex.

The age at which individuals reach peak fertility is 22 years old, on average, according to data collected in the Archives of Sexual Behavior. [5]

However, for the purposes of this guide, we’re going to further discuss peak fertility in terms of when you are most likely to conceive during your monthly cycle. Therefore, peak fertility can be defined as: [3]

  • The time in your menstrual cycle where you are most fertile
  • The time frame during which intercourse is most likely to result in conception

If you wish to become pregnant, you should try to have intercourse on your high fertility and peak fertility days. This provides the best chance of conception.

When does peak fertility occur, and how long does it last?

Peak fertility occurs during the day before ovulation and the day you ovulate.

These two days are thought to be the two days during your cycle when you are most likely to become pregnant if you have unprotected sex. [3]

However, many individuals don’t have perfectly regular cycles. Those with irregular periods experience cycles of varying lengths. This means that during some months, ovulation may occur on the 10th day of the cycle. Other months it may occur on day twelve or fourteen. Pinning down the exact days of peak fertility is very difficult and can vary from month to month depending on the ebb and flow of your cycle.

What are the differences between high fertility and peak fertility?

Both high fertility and peak fertility are periods in which the likelihood of conception after unprotected intercourse is highest. The most significant difference between high and peak fertility is that peak fertility occurs closer to the time of ovulation—the day before and the day of ovulating.

High fertility encompassesed the few days before ovulation when sperm left behind during intercourse can remain in your body until you ovulate.

How can you track your fertility?

So, now that you know there are specific days when you are most likely to get pregnant, how do you use this information to your advantage? There are several ways that you can track your cycle to determine which day ovulation will occur. These include: [6]

  • Calendar method – Using a calendar or app to track your cycle can take a little while, but it can provide some helpful insight into when you are most likely to ovulate. This method works best if you have consistent periods and a cycle that is typically about 28 days in length. You’ll need to keep track of your period start and end dates for several months. This allows you to pinpoint the day each cycle that ovulation occurs (around day 14) and plan to have intercourse on the two days before and the day of ovulation.
  • Cervical mucus – Your cervical mucus changes throughout your cycle. Your hormones fluctuate making the mucus thicker or thinner, depending on where you are in your cycle. Right before and during ovulation, the mucus becomes more slippery and clear in appearance. This is to allow sperm to more easily reach your eggs. Charting the texture and color of your cervical mucus for several cycles can help you determine the approximate day you ovulate.
  • Body temperature – Did you know that your body temperature changes slightly when you ovulate? By tracking your body temperature every day before you get out of bed in the morning, you’ll notice a sustained increase in body temperature for several days in the middle of your cycle. This is typically a solid indication that ovulation has occurred. You should keep a chart noting these increases in body temperature over several cycles to pinpoint your fertile days.

For the best results, you may want to use all three of these methods together. Paying close attention to and tracking your body’s signals can help you understand your cycle’s unique characteristics and pinpoint when you are likely to ovulate.

What other factors can interfere with conception?

While understanding your cycle and ovulation can help you conceive, sometimes other factors slide in and prevent you from getting pregnant. Some of these include: [7]

  • Damage due to untreated STDs in you or your partner
  • Blocked fallopian tubes
  • Uterine fibroids or endometriosis
  • High levels of stress
  • Hormonal imbalances
  • Thyroid problems
  • Low sperm count or poor sperm health
  • Certain medications
  • Underdeveloped eggs
  • Misshapen uterus
  • Your age, especially if you are over the age of 35
  • Smoking, drug use, or excessive alcohol use
  • Being over or underweight
  • Exposure to certain environmental toxins, pesticides, or pollutants

The one question people ask is, "Does birth control affect fertility?" Thankfully, once you've stopped birth control, it shouldn't interfere with your ability to get pregnant.

If you’ve been trying to get pregnant for a full year without success, then you may want to seek professional help. A specialist can give you more insight into why you’re having trouble conceiving and provide options that can increase your chances of pregnancy. Although infertility can be really frustrating, there are often treatments and solutions that can help.

Gain a better understanding of your fertility hormones with Everlywell

We are fortunate to live at a time when technological advances have led to a better understanding of human reproductive health.

We have modern fertility treatment options for individuals who want to get pregnant, ovulation predictor kits for those who want to track their fertility, and pregnancy test options.

Research has provided insights into when those who wish to become pregnant might be best able to conceive. High fertility and peak fertility days are thought to be the best days to try to get pregnant. However, some people still struggle to get pregnant.

If you want to learn more about your fertility levels, then we might be able to help. The Everlywell Women’s Fertility Test measures the levels of five key fertility hormones. All it takes is a simple finger prick, and then you submit your sample to one of our secure labs. Your results will provide you with insights into your hormone levels to help you understand if your fertility is where it needs to be for conception.

Try our fertility test today and take charge of your reproductive health.

Does birth control affect fertility? Effects of birth control on fertility

Are you fertile after your period?

What are the signs of high fertility in a woman?

Understanding the relationship between endometriosis and fertility

3 symptoms of failed implantation of fertilized egg


  1. Menstrual Cycle. Mayo Clinic. URL. Accessed August 1, 2022.
  2. Luteinizing Hormone (LH) Levels Test. NIH. URL. Accessed August 1, 2022.
  3. Real-Life Insights on Menstrual Cycle and Ovulation Using Big Data. PubMed. URL. Accessed August 1, 2022.
  4. When Are You Most Likely to Conceive? Fertility.org. URL. Accessed August 1, 2022.
  5. Public-Perception of Female Fertility. Archives of Sexual Behavior. URL. Accessed August 1, 2022.
  6. Fertility Awareness. Planned Parenthood. URL. Accessed August 1, 2022.
  7. Infertility. Planned Parenthood. URL. Accessed August 1, 2022.
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