Phases of the menstrual cycle: The Follicular phase

Katherine Maslowski

Have you ever wondered what is actually happening in your body every month during your cycle? Or how your periods happen? Periods and the menstrual cycle are discussed much more now than they ever used to be, but it can be very confusing. Over the next little while, we are going to talk about the different phases of the menstrual cycle and what happens in our bodies during each phase. Today we will continue by talking about the follicular phase.

If you missed the last article about the menstrual phase you can find it here!

If you read the last article and don’t want a repetition of what the menstrual cycle is, you can skip forward to the part called “The follicular phase”

What is the menstrual cycle?

The menstrual cycle is the cycle of hormones that control our periods (and lots of other things in our bodies)

The main hormones involved are:

  • estrogen,
  • progesterone,
  • luteinizing hormone (LH) and
  • follicle stimulating hormone (FSH).

LH and FSH are produced in our brain and then travel through the blood to the ovaries. The ovaries produce estrogen and progesterone. The interaction between these hormones is what controls ovulation (when the ovaries release an egg) and our periods.

The menstrual cycle is what allows us to become pregnant. Our bodies “get ready” for a pregnancy each month and then if there is no pregnancy, we have our period and the cycle starts again.

Of course, contraception (birth control) interrupts this cycle. This is how it stops us from getting pregnant. We aren’t going to talk about contraception today but if you are interested then check out this article.


What are the different phases of our menstrual cycle?

The menstrual cycle can be divided in various ways. This depends on whether you are looking at what is happening in the uterus (womb) or the ovaries. The different names for the different phases can get very confusing and very ‘medical’ so we are going to try and avoid that.

Generally, the menstrual cycle can be divided into two halves:

  • the follicular phase and
  • the luteal phase.

There are also two ‘events’:

  • menstruation (your period) and
  • ovulation

It is very important to remember that everyone is different. There is a ‘textbook’ explanation of the menstrual cycle but not everyone will experience this. To explain the cycle I will use an example cycle that is 28 days long.

Any cycle between 21-35 days in length is considered ‘normal’. Some people have regular periods that occur at exactly the same time each month. Some people don’t. Everyone is different.

What matters is what is normal for you. Irregular periods (when you can’t predict when your period is going to start because it is random) might warrant talking to a doctor.

The diagram below shows what is happening during the different phases of the menstrual cycle. Along the top is what is happening in the ovary. The middle of the graph shows the hormones and the bottom is what is happening in the endometrium (lining of the uterus).

illustration of the menstrual cycle


 Source: Encyclopaedia Britannica


The follicular phase

The follicular phase is the “first half” of the menstrual cycle. I put first in quotations because there isn’t really a beginning and an end (it is a cycle!) but usually we refer to the follicular phase as the beginning. It includes the days from the start of your period up until ovulation. In a “textbook” example of a 28-day cycle, this would usually be days 1-14.

The follicular phase is the part of the menstrual cycle that varies most between different people.

The follicles are bundles of cells that each contain an egg. Lots of follicles develop during the follicular phase and then one dominant follicle is ‘chosen’ to continue developing.

Hormonal changes

During the follicular phase, the levels of LH and progesterone are low while the FSH level is higher and estrogen increases throughout the follicular phase.

FSH is produced in the brain and tells the ovarian follicles to develop. As the follicles develop, they produce more and more estrogen which is what leads to rising estrogen levels.

Physical changes (follicular phase “symptoms”)

The hormonal changes during the follicular phase of the menstrual cycle cause changes in both the ovaries and the lining of the uterus (endometrium). Most of the changes during the follicular phase are nothing you will notice. The changes in the ovaries and the endometrium are happening inside your body where you are unaware of them.


In the ovaries, lots of follicles are developing during the early part of the follicular stage. Then one dominant follicle is “chosen”, and the other follicles get reabsorbed by the body. The dominant follicle continues to grow and produce estrogen until the signal for ovulation happens.


From the endometrium’s (lining of the uterus) point of view, the follicular phase is sometimes referred to as the proliferative phase. This is because the endometrium is proliferating (building itself back up) during this time.

The first part of the follicular phase is the period. After the period has finished, the endometrium starts to grow and thicken again to get ready for a possible pregnancy.

Cervical mucous/vaginal discharge

The mucous produced by our cervix also changes over the cycle. This is what we see as vaginal discharge. During the first part of the follicular phase, we are bleeding. After the period stops, a lot of women might have a “dry phase” where they don’t notice much discharge at all.

As you get closer to ovulation (the later part of the follicular phase) then your discharge will likely increase. It might be stretchy or gluey and is usually white or slightly yellow. This is the cervix getting ready to help sperm get through around the time of ovulation.

Other physical changes

The increasing estrogen during the follicular phase can also cause changes to the skin. Some women find that their skin is clearer, and acne improves during the first half of their cycle.

Psychological changes

The hormonal changes over the course of our cycle can dramatically change our mental state.

Some women find that their mood and energy levels are better during the follicular phase (and around the time of ovulation). This is (at least partly) because of the rising estrogen levels during the follicular phase.

Estrogen can help to reduce the effects of hormones involved in stress which can help improve our mood.

Some women also find their sex drive increasing during the follicular phase. Energy levels are often higher during this phase so you may feel more able to exercise or socialise compared with other times in your cycle.


Follicular phase length

The length of the follicular phase can vary a lot between different people. A shorter follicular phase will lead to a shorter menstrual cycle overall and vice versa.


What next?

Hopefully, you now have a better idea of what is happening during the first half of your cycle. Next time we will look at what happens next, during ovulation.

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Katherine Maslowski

Katherine Maslowski

Katherine is a junior doctor from New Zealand who has experience working in Obstetrics and Gynaecology and is currently studying an MSc in Women’s Health. She is passionate about women’s health and empowering women to learn about their bodies and understand how they work. She is particularly interested in sexual and reproductive health and helping women to make educated, informed choices about their health and wellbeing.