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Hertility’s menstrual cycle basics: Focus on the follicular phase

Periods 101
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Hertility’s menstrual cycle basics: Focus on the follicular phase

Welcome to our second blog in our Menstrual Cycle Basics series with HertilityUp next? Let’s get intimate with the follicular phase of your menstrual cycle.

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Check-in on your menstrual health today with Hertility's at-home Hormone & Fertility test, using code SISTER10 at checkout to get £10 off. Get to the bottom of any hormone imbalances, identify your egg count and warning signs of infertility and screen for 18 reproductive health conditions, all in just 10 days. We know it can be daunting but don’t worry, you’ll be assigned your own personal gynae to review your results and streamline you to specialist care should you need it.


What is the follicular phase?

The first act of the menstrual cycle show is the follicular phase. Overlapping with the menstrual phase, it starts on the first day of your period and lasts about 10 -16 days right up until the big mid-cycle show-stopper event happens - ovulation!

We are all born with all the eggs we will ever have and they remain housed in these fluid-filled sacs in the ovaries called follicles - this is called the ovarian reserve. The follicular phase’s main job is to mature the eggs in your ovaries during each cycle. This process of maturation is strictly controlled by your hormones - the little chemical signals moving through your blood that control many important functions in your body.

Which hormones are involved?

First of all, your brain makes gonadotropin-releasing hormone (GnRH) to kick-start the party. GnRH then triggers the release of another hormone,follicle-stimulating hormone (FSH), from the brain. FSH, as you might have guessed, sends a signal to the follicles to tell them to grow (also known as maturation). But not all your eggs will mature at the same time. Only a small number of eggs will get selected to undergo maturation every cycle.

Now, as these follicles grow and do their thing, they start making another important hormone you may have heard of before - oestrogen. Oestrogen is what keeps your skin glowing and hair shining, along with controlling your mood and memory, looking after your bones and your heart…the list goes on!So, you may notice that you feel your best during this phase with improved skin and hair, energy levels, productivity and creativity. This could be a good time to consider starting that class you’ve been putting off, hitting the gym or scheduling those important meetings!

But not all the eggs make it to the finish line. Around day eight of your cycle, only one follicle will be picked as the chosen one, and the others will stop maturing. This chosen one, referred to as the dominant follicle, will keep growing until it is mature enough to be ovulated (released from the ovaries) but more on this in the next blog post! 



Hertility is founded by scientists and powered by an (all-female) research team. We know the science of hormones and the intricate roles they play in your reproductive and overall health. That’s why our at-home Hormone and Fertility tests take a whole body approach to ensure we’re testing every hormone that could be the cause of any symptom you’re experiencing. Don't forget to use code SISTER10 at checkout to get £10 off.

If you have any more questions, we'd love to hear from you! Drop us an email at

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