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  • optimal days when the sexual intercourse can lead to conception
  • for women who cannot get pregnant, although they are healthy (primary sterility) and their husbands are also able to have children
  • when at least one of the woman’s ovaries is functional as well as the oviduct and womb; and in the man the sperm is present (if there is so called reduced number of sperms, this does not mean that the couple cannot have children)
  • determined for each woman individually according to her biorhythm
  • independent of period cycle
  • no medication is taken
  • no negatives effect on the body or pregnancy
price: 27€


  • create a user account
  • fill out your personal data in the form (date of your birth, previous pregnancies, etc.)
  • to pay the fee for the calculation: by credit/ debit card, PayPal or bank transfer
  • the calculation is made and activated within 3 days after the data and the payment have been received


  • one year fertility chart beginning with your last period; if your period is absent (e.g. due to childbirth, etc.), the calculation will start from the current month
  • the calculation also contains instructions that need to be followed
  • the interactive calendar on webpage (in your account) app that you can use in your mobile device


Jonas method of Natural conception control is correct in 98,6% of cases.

All data needed for a calculation are strictly confidential (medical confidentiality) and are used for the calculation only.

My husband has a problem with sperm formation, can I nevertheless get pregnant?

The problem with sperm formation is, unfortunately, very common nowadays. But for a conception one single sperm is necessary. The condition might be improved by changing habits.
Vitamins C and E have a positive effect on sperm formation. The grape seed extract, which is rich in antioxidants, is very beneficial. Another option is an extract from the plant Lepidium meyenii (maca). Food types such as dairy products, eggs, lean red meat, liver, nuts can also help. Limit the consumption of alcohol and cigarettes.
Naturally, this is a long-term process.

I was diagnosed with endometriosis / PCO. Can I still get pregnant?

About 50% of our clients suffer from these diseases. Calculations have been successful even in these cases. It is very individual though. Please mention this in your application form.
In order to improve your condition (period cycle, endometriosis, PCOS, fibroids, strengthening the wall of the womb, other), the lady's mantle tea (Alchemilla) has a positive effect. The tea should be drunken 6 days a week; the seventh day is without tea. For instance, the tea is drunken from Monday to Saturday, on Sunday no tea. This cycle 6+1 is repeated. It is good to start with 2-3 cups a day and gradually reduce the dosage to one cup a day.

Can we succeed despite the fact I and my husband have certain health problems?

The calculations of natural conception control show your fertile days, i.e. the days when you can conceive.
Therefore the calculation can be used when a spontaneous pregnancy is possible (i.e. at least one of the woman’s ovaries is functional as well as the oviduct and womb; and in the man the sperm is present).
Otherwise the health problems have to be consulted with and eliminated by medical specialists.

My period is very irregular/ absent, can I still get pregnant?

Not every woman has a regular period every 28 days. Usually the cycle fluctuates over several days, which can be caused by various factors such as illness, stress, etc.
However, there are also women who are menstruating only once or twice a year or not at all and medical examinations do not show any health problems. Even in such cases our calculations have proven to be successful, because the absence of menstruation does not automatically mean that a conception is impossible.
For example, even women just after childbirth who are not yet menstruating can become pregnant. The earliest case of pregnancy after a childbirth we recorded was just 5 weeks after delivery.
If menstruation is not present due to menopause, when the ability to conceive ends, pregnancy will no longer occur.

How long does it take to get pregnant?

It is a very individual matter, whether you get pregnant on the very first date shown in a calculation, or whether it will take longer. Statistically, during the first year of using our calculations two thirds of the women become pregnant, in the second year the next half of them and in the third year also the rest of the women.

I am interested in my Fertile Days Calculation

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