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Period calendar

How to calculate your period?

It is worth being prepared for your period. In order to estimate when it is due, you need to consider your average cycle length as well as the date when your last menstruation started and how long it lasted.

How period calendar works

Na podstawie wprowadzonych przez Ciebie danych, otrzymasz prognozy dotyczące kolejnych miesiączek i zbliżających się dni płodnych.


menstruation fertile days ovulation

Menstruation calendar Bella

is a free mobile application that will help you better control your cycle.

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Period symptoms

  • At the beginning of a period, bleeding is heavier, but it becomes lighter towards the end.
  • Abdominal pain appears usually on the first day of bleeding and can radiate to the lower back. Usually, the pain wears off over time.
  • Gastric disorders – some women may suffer from various gastric symptoms, such as diarrhoea, constipation, nausea, and vomiting.
  • Increased eruptions on the face and body (mainly chest) is caused by lower oestrogen levels, which makes skin dry and sensitive.

What causes fertile days to shift?

Remember that the ovulation calculator and observing your body do not guarantee precise calculation of your fertile window. There is a range of factors that may cause ovulation and fertile days to shift, such as:
– strong stress,
– illness in the first cycle phase and antibiotic use,
– heavy physical strain,
– diet and weight loss,
– climate change,
– sleep deprivation,
– general fatigue.

Ovulation calculator

If you would like to know when your fertile window is due, monitor your body thoroughly. In order to calculate it accurately, you should know your average cycle length and how long your last menstruation was.

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Happy Baby Application

Your personal calendar for pregnancy and the first months after childbirth. It contains many tips and practical tools, supporting parents from the moment of conception.

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Explore the products pokaż wszystkie

Menstruation calendar Bella

is a free mobile application that will help you better control your cycle.

learn more

Tips for teenagers

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Tips for all
of us

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Tips in menopause

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