Fertility

High Fertility vs. Peak Fertility: What's the Difference?

Kylie Han

High fertility and peak fertility make up your fertile window, the part of your menstrual cycle when you are most likely to get pregnant. Here’s how they differ.

Published:

Apr 3, 2025

Est. Read Time:

4 minutes

The fertile window refers to the short timeframe when you are most likely to get pregnant if you have unprotected sex. It’s made up of both high fertility and peak fertility points in your menstrual cycle. Learning about high and peak fertility can help you identify your fertile window and increase your chance of pregnancy during intercourse if you’re trying to conceive.

Understanding the menstrual cycle: the fertile window

The fertile window typically includes the five days before ovulation and 24 hours after you ovulate in your menstrual cycle. An average menstrual cycle lasts 28 days but can range from 21 to 35 days (1).

During your menstrual cycle, estrogen and progesterone fluctuate to prepare the body for pregnancy. These hormones rise to thicken the uterine lining and support the development of a mature egg. Ovulation occurs when one of the ovaries releases the egg, usually at the halfway point of your cycle (around day 14).

The egg then travels down one of your fallopian tubes to your uterus, where it waits to be fertilized by sperm. If the egg is fertilized by sperm, it attaches to your uterine wall, and you become pregnant. Sperm can live in your fallopian tube for up to 5 days and fertilize the egg as soon as it’s released. This means your window to conceive, or fertile window, consists of the five days before you ovulate and one day after. If you’re trying to get pregnant, having sperm already in your body when you ovulate will increase your chances of conception.

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>>MORE: When Am I the Most Fertile?

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High fertility vs. peak fertility

High and peak fertility are the parts of your menstrual cycle when you are most likely to conceive. Together they make up your fertile window.

High fertility begins when estrogen levels rise during your menstrual cycle. It usually includes the five days leading up to ovulation and lasts until the beginning of peak fertility. One sign of high fertility is changes to your cervical mucus. Cervical mucus is a vaginal fluid produced by your cervix. Before ovulation, your cervical mucus will turn from thick, white, and dry to clear and slippery, making it easier for the sperm to reach the egg. Some other signs of high fertility include breast tenderness, bloating, some pelvic pain, changes in position and softness of your cervix, and increased sex drive.

Peak fertility refers to the specific timeframe right before ovulation when luteinizing hormone (LH) levels surge. It consists of the day before ovulation and the day you ovulate (2). This is the moment you are most fertile and most likely to get pregnant in your menstrual cycle. The LH surge is responsible for ovulation. Estrogen levels rise, and once it reaches a certain threshold, estrogen triggers the LH surge, which causes ovulation. Once it occurs, ovulation takes place within 36 hours and only lasts for a small window of time (3). The LH surge occurs the day before ovulation and after ovulation, the egg is only viable for 12 to 24 hours. Once LH surges, you’ll want to have unprotected sex as soon as possible if you’re trying to conceive, but it’s recommended to time intercourse throughout your entire fertile window to increase your chances of pregnancy.

However, peak fertility can vary and sometimes LH surges without releasing the egg (4). This can happen as a result of irregular cycles, hormone imbalances, or health conditions like PCOS. Additionally, LH surges can look different from individual to individual. Some may experience one spike or multiple LH spikes which can result in more or fewer peak fertility days. Even if you have a different LH surge pattern, you’ll still only have one LH spike that triggers ovulation (5).

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>>MORE: How to Track Ovulation: Finding and Testing Your Fertile Window

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High fertility vs. peak fertility: the bottom line

Knowing your fertile window is important if you’re trying to conceive. There are different methods for tracking your high and peak fertility such as recording your menstrual cycle in a calendar, observing the texture of your cervical mucus, monitoring your basal body temperature, or using at-home hormone tests like Oova. Even though peak fertility is the moment you are most fertile, you have a greater chance of pregnancy throughout your entire fertile window when you experience high fertility leading up to ovulation compared to the rest of your cycle. Trying to conceive is a different experience for everyone, and can be long and difficult for some. While there are many other factors that come into play, timing intercourse during high and peak fertility is a crucial way to increase your chances of conception.

About the author

Kylie Han is a writer from Oakland, California. She's the SEO Manager at The Infatuation, where she loves to support the work of writers and highlight local restaurants. She is also a contributing writer at The Infatuation and is excited to get involved in reproductive health, a passion of hers.

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About the Oova Blog:
‍Our content is developed with a commitment to high editorial standards and reliability. We prioritize referencing reputable sources and sharing where our insights come from. The Oova Blog is intended for informational purposes only and is never a substitute for professional medical advice. Always consult a healthcare provider before making any health decisions.

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