The follicular phase is the first phase of your cycle, which starts with your period and ends with ovulation. During this phase, your body prepares for ovulation and there's an increase of hormones to initiate the ovulation process, such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH). During this phase, the app may recommend you to take an LH test to find your LH surge, which indicates that ovulation may occur within the coming 48h. Read more here about LH tests.
During the second half of the follicular phase, the estrogen levels also increase which makes the uterine lining (endometrium) create a thicker lining to prepare for the coming egg. The increased estrogen levels also create more cervical fluids, which will increase the PH level to improve the environment for the sperm and help the sperm travel up to the fallopian tubes.
How long is the follicular phase?
It's difficult to set an exact number, as the follicular phase may vary from cycle to cycle, but also from woman to woman. If you have an irregular cycle, you will see that your follicular phase varies more for each cycle – this is as the luteal phase (post-ovulation) is normally the same length in each cycle. You will see individualized data in your My cycle tab, which will inform you of how long your follicular phase is on average, and if it varies.