Are you worried about the length of your menstrual cycle? Read more about menstrual cycle issues

Do you know the hormones that regulate the phases of your menstrual cycle? What causes changes in the length of the menstrual cycle? We’ve put together a databank of hormones, what they do, and the most common causes of a short or long menstrual cycle.

Short menstrual cycle

The normal length of a cycle is 24-38 days, and it is measured from the first day of your period to the start of your next period. It is very common for the length of the cycle to vary by a few days, and sometimes even weeks.

If your menstrual cycle is repeatedly shorter than 24 days, you should see a gynaecologist to try to figure out the cause of the short cycle. In young people, a short cycle often indicates early ovulation and the effect of a luteal hormone deficiency. It is not necessary to treat the issue, but it can be treated using a course of progesterone prescribed by a doctor and taken on the 15th-24th day of your cycle. In particular, when trying to get pregnant, it is important to know the date of ovulation, so a chat with a doctor might be a good idea.

The menstrual cycle can also be shortened by the perimenopause, which begins around 4-10 years before your periods stop. During this phase, the person’s fertility has clearly decreased and their eggs are of poorer quality.

Long menstrual cycle

A long menstrual cycle refers to a cycle that is repeatedly longer than 35 days. This indicates that ovulation occurs rarely or not at all. Ovulation issues cause concern, especially when trying to get pregnant. It is not possible to get pregnant without ovulation.

The most common cause of ovulation issues is being overweight, or PCOS, which includes excessive hair growth under the bellybutton and on the breasts, and acne. PCOS is commonly diagnosed during infertility treatment and confirmed with an ultrasound.

Other reasons for changes to the menstrual cycle

After periods begin, it can take a couple of years before they settle into their natural rhythm. If any sudden changes occur it is good to keep in mind that sudden weight gain or loss, as well as stress, can also disrupt your cycle.

Untreated diseases such as an underactive thyroid can also cause disruption to the menstrual cycle.

Learn your hormones

Do you know the names of these important hormones? Everyone should know the names of these hormones and what they do.

FSH = follicle-stimulating hormone, secreted in the pituitary gland and matures the ovarian follicle
LH = luteinizing hormone, produced in the pituitary gland and triggers ovulation
Oestradiol = female sex hormone, produced in the ovarian follicles and thickens the lining of the womb
Progesterone = a luteal hormone that causes the lining of the womb to mature ready for pregnancy


Sources: Duodecim Terveyskirjasto,,,

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