There are a lot of different factors that need to balance well for you to have a normal period. Any change in those factors causes a change in your period. It may be a change in the cycle length, pain, or the heaviness or lightness of your flow.
There are many factors at play behind these which will be explored here so that you can have a better understanding of what’s going on in your body.
Your period is classified as late if your cycle has been over 35 days.
Late periods tend to indicate either a long follicular phase or that you have not ovulated this cycle. A long follicular phase has different causes depending on your age.
If you are under 45, it may be because of stress, illness, undereating or PCOS. Over 45 and you need to consider thyroid health and, potentially, starting the transition to menopause.
If your period cycle is less than 21 days, it is considered early. There are three different reasons for a short cycle:
- An anovulatory cycle: you have not ovulated this cycle.
- Short follicular phase: most common in perimenopause as the pituitary is producing more follicle stimulating hormone (FSH) which speeds up ovulation. Extra FSH also increases oestrogen levels, compared to when you were younger.
- Short luteal phase: caused by many of the same things that cause a lack of periods such as stress or undereating. It is also associated with low progesterone. Fertile mucus production and temperature tracking can be used to help determine your progesterone levels.
This hormone is important in period regulation. It helps to support healthy ovulation, which is also how you have a regular cycle.
You need enough progesterone to support your luteal phase and you get more progesterone by having a healthy ovulation cycle. It is a self-supporting cycle that lasts the full 100 days it takes your follicles to mature.
Low progesterone levels are also associated with other health conditions such as PCOS, fibroids, acne, heavy periods, hair loss, and premenstrual syndrome.