The follicular phase is the longest phase of your menstrual cycle. It lasts from 14 to 21 days. During the follicular phase, your ovaries house a developing egg they will later release during ovulation. The end of your follicular phase is a particularly fertile period, when your odds of getting pregnant increase if you have sex.
The follicular phase refers to that part of your menstrual cycle when an egg matures in your ovaries. It’s part of an ongoing process in your body during your reproductive years when hormones activate changes in your body that make it possible for you to become pregnant.
Your menstrual cycle consists of two phases: the follicular phase and the luteal phase. Menstruation (your period) and ovulation are important events during your cycle that correspond with each phase.
With menstruation, the cycle repeats.
You’re born with about a million eggs. This reserve declines as you grow older. Once you start menstruating, your body begins a process of maturing these eggs. Only a select few fully mature over your lifetime. During the follicular phase of your menstrual cycle, around 11 to 20 eggs begin developing, but only one matures completely.
Hormones in your brain and your ovaries regulate the changes in your body that make this process possible.
Toward the end of the follicular phase, high estrogen levels trigger your pituitary gland to release a surge of luteinizing hormone (LH), the hormone associated with the luteal phase. LH activates the mature egg to escape the follicle and the ovary (ovulation).
The average menstrual cycle lasts from 28 to 35 days. The follicular phase ranges from 14 to 21 days. The luteal phase lasts about 14 days. Unlike the luteal phase, which stays fairly consistent, the length of your follicular phase may vary at different stages of your life.
The length of your follicular phase depends on how long it takes the dominant follicle to form a fully matured egg.
Having a long follicular phase doesn’t mean you’re less likely to become pregnant. A long follicular phase most likely means that your menstrual cycle is longer, too. You can have a long follicular phase for a variety of reasons:
A short follicular phase could indicate that you may have trouble becoming pregnant. It’s common for your follicular phase to shorten (for example, from 14 days on average to 10 days) as you approach menopause. Menopause signals a shift in your life when you no longer get your period.
Starting in your late 30s, your FSH levels may still increase during your follicular phase, but your LH levels may not spike as they did previously. As a result, the follicle may mature faster than the egg inside and release it too soon. These eggs may not be viable for pregnancy.
Yes. You have the greatest chance of becoming pregnant if you have intercourse during the five days leading up to ovulation and on the day you ovulate. This timetable provides an ideal window for an egg and sperm to meet. Ovulation calendars can help you keep track of your cycle.
Your body temperature at rest provides clues about the various phases of your menstrual cycle. Knowing when you’re in the follicular phase can be useful if you’re trying to become pregnant.
Take your temperature each morning at the same time, right after you wake. During the follicular phase, your temperature should range between 97 and 97.6 degrees Fahrenheit. It should increase during ovulation and remain elevated when you’re in the luteal phase.
A note from Cleveland Clinic
Knowing when the various phases of your menstrual cycle are occurring can help you plan the best time to try for a baby. You have the best chance of becoming pregnant in the days surrounding ovulation, including the end of the follicular phase. Speak to a healthcare provider or a fertility specialist about the best strategies for tracking your cycle and symptoms to increase your likelihood of becoming pregnant.
Last reviewed by a Cleveland Clinic medical professional on 08/08/2022.
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