Follicular phase: What it is, symptoms, & what to expect

What is the follicular phase?

The follicular phase is the early part of your monthly menstrual cycle that starts on the first day of your period. During this time, the body is working to mature ovarian follicles, hence the name “follicular” phase [1]. Ovarian follicles are small sacs that contain oocytes (undeveloped egg cells) surrounded by other types of cells that will eventually help the egg mature. This maturation process within the follicle prepares the egg for potential conception. Women are already born with all of their follicles [2].  

When does the follicular phase happen?

The first day of menstruation marks day one of the follicular phase, and day one of your overall cycle (learn more about your period in the context of your entire cycle here) [3]. This may seem counterintuitive, as menstruation can often feel like the ending of a cycle.

But from the start of your period, the follicular phase lasts about 10 to 16 days (including the days of your period) according to clinical guidelines [1]. However, this menstrual cycle phase comes with the most variation in length. It’s common to have longer or shorter follicular phases at different times of life. Some of the largest variation comes around the time of perimenopause [4]. In fact, one study performed with Natural Cycles data from over 600,000 cycles found that the follicular phase lasted an average of 17 days, and the mean follicular phase length decreased by about .19 days per year from ages 25 to 45 [5].

Technically, the follicular phase ends when you ovulate, which, without the right knowledge and tools, can be difficult to predict and detect. Learn more about the signs of ovulation here. Chemically, a surge of luteinizing hormone (LH) results in the release of the mature egg cell, marking the start of ovulation — the next phase of your menstrual cycle [4].

What’s happening in my body during the follicular phase?

The main function of the follicular phase is to grow and develop ovarian follicles. Both estrogen and follicle stimulating hormone (FSH) rise gradually over the course of the follicular phase. FSH influences the egg cells to mature, and the follicles can grow up to 21 millimeters in diameter by day 12 [3]. (Fun fact: mature egg cells are the largest cells in the human body [6]!)

Rising estrogen also influences the body to thicken the uterine lining with more water and open blood vessels throughout this phase. This lining will eventually be shed during your period if pregnancy does not occur. Estrogen levels rise throughout the follicular phase, resulting in a peak in the few days before ovulation. Approximately a day or two after this peak a surge of LH occurs. The LH surge is accompanied by a smaller FSH rise, along with a slight rise in progesterone. All of these shifts lead to ovulation, the end of the follicular phase [3].

What are some common symptoms of the follicular phase?

The most obvious symptom of the start of your follicular phase will be the onset of your period, which may also come with common menstrual symptoms like period cramps [7]. But this should only last through the first couple of days. Once estrogen begins to rise around day five of the follicular phase, you may notice your period ending along with other follicular phase symptoms including:

Changes to cervical mucus

Right after your period, you might notice very little discharge. If there is any, it may be thick in texture. As the follicular phase progresses, it’s likely that you’ll notice more cervical mucus in the form of discharge, and it’ll become clear and stretchy in texture [8].

Lower basal body temperature (BBT) 

Your basal body temperature will also be relatively low during the follicular phase, and it only rises after ovulation [9]. If you’re tracking your BBT each day with a tool like Natural Cycles, you’ll be able to see patterns emerge over time and get a good idea of the length of your unique follicular phase.

Increased energy

The rise in estrogen and low progesterone during the follicular phase can result in a boost of energy in a number of different ways. You may be sleeping better than you do during the luteal phase, so you might be feeling sharper mentally from getting high-quality rest. Lower progesterone during the follicular phase can also mean that you’re feeling less anxious during this time, and your moods may be a bit more stable [10, 11].

How will I feel during the follicular phase?

It’s important to note that each person’s experiences of the hormonal shifts that happen throughout the menstrual cycle are highly variable and unique to their circumstances. For example, if you:

• Take hormonal birth control
• Have polycystic ovary syndrome (PCOS)
• Experience irregular periods
• Have anovulatory cycles
• Experience excess stress in your daily life

Any of these can affect each phase of your menstrual cycle as well as how you experience it [11]. While the follicular phase symptoms listed above are associated with increased estrogen or decreased progesterone, women’s health has been historically underfunded and understudied, and research on the follicular phase is still somewhat limited. Try not to feel discouraged if your cycle experience doesn’t exactly align, and consult your healthcare provider if you have concerns about your health.

Tips for your follicular phase

Curious about ways to support your body and lifestyle during the follicular phase? We’ve collected a few tips for you to try below.

Self-care and productivity during the follicular phase

If you notice that you tend to sleep better during the follicular phase, you might want to budget a bit more time for sleep to maximize that benefit. The possibility of more energy and mental focus during the day means you may also be more productive with your work and more social with friends and family. If possible, tackle any big projects during this phase if you’re feeling that your energy is typically up. 

Just be mindful of your mental health as well, noticing if any signs of anxiety or excess stress start to arise — that may be a signal to pump the brakes. Tracking your symptoms over time with Natural Cycles can help you see when you typically feel the unique highs and lows of your cycle over time.

How to tailor workouts during the follicular phase

Estrogen plays a role in keeping our energy levels constant and regulating metabolism, which can be great for your workouts [12]. Many people find that the follicular phase is the time of the month when they feel most active, so do your best to take advantage of that and carve out some time for your favorite type of movement — whether that’s cardio, weights, yoga, dance, or anything that serves your body. While it’s safe to exercise during all phases of your cycle, you may feel the most motivation during the later part of your follicular phase when estrogen is peaking [13].

Studies have shown that the increase in estrogen during the follicular phase has cardioprotective benefits, including:

• A widening of blood vessels that helps maintain healthy blood pressure
• An anti-inflammatory effect throughout the heart and blood vessels
• Regulation of cholesterol levels

Regular movement over time will have the most impact on your overall health, but you can take these subtle hormonal fluctuations into account each month when planning your exercise routines [11].

How to tailor your diet to the follicular phase

Aside from exercise, your dietary needs may also change during the follicular phase. Several studies have found that menstruating females typically consume fewer calories during their follicular phase, and it’s possible that estrogen may have an appetite-suppressing effect. For you, this means that you may not feel quite as hungry this time of your cycle. It’s important to make sure you’re still getting all of the nutrients your body needs, so be sure to consult your healthcare provider for personalized nutrition recommendations and strategies, as each person’s dietary needs are very unique [14].

Can you get pregnant during the follicular phase?

Yes, it’s possible to get pregnant if you have sex during the follicular phase. While fertilization and conception technically don’t happen until the day of ovulation and afterward, respectively, sperm can live for up to five days in the female reproductive tract. That means that if you have unprotected intercourse in the days right before ovulation during your follicular phase, this could lead to pregnancy [15].

Learn more about your menstrual cycle with Natural Cycles

Understanding your follicular phase by tracking your symptoms with Natural Cycles can empower you to make informed decisions about your lifestyle, fertility, and more. To learn more about your menstrual cycle and pinpoint your follicular phase each month, explore Natural Cycles — the science-backed FDA Cleared birth control app that’s designed to help you understand your body.