Dear Centrum, I am very glad that this method of natural conception exists. Since I don’t use artificial means, I value this method...
Dear doctor, You have advised us and now we have a beautiful, healthy boy. For all you have done for us, thank you so much!
Dear Mr. Jonáš, 34 years ago you made a calculation for my parents, when they should conceive me. I even have a picture with you when I was...

Natural Conception Control - "Jonas Method"

In 1956, August 15, Dr. Eugen Jonas discovered his first thesis in the field of natural conception control and he devoted his discoveries to Virgin Mary on the very same day, as it is the Day of Assumption, to help women and mothers, who ask for a calculation.

It was his response to the law that legalised abortions in Hungary.
The method of Dr. Jonas is based on two independent cycles of fertile days in women. No medication is taken thus the method has no negative effect on the body.

It turned out that the natural conception control has a potential for further use besides contraception.

In the following years I have elaborated my method and now I offer 8 different calculation types for women.
They vary from the calculation of infertile days (natural contraception), through the calculation of fertile days and of conception of a viable child to gender selection.

The accuracy of my calculations has been proved during 35 years and is reliable in 98% of cases, which is the maximum in the field of natural sciences and medicine.

At the moment I focus my research on calculations of the gender of the first child, which is determined already at the point of birth of the woman - future mother. The reliability is so far only 70% and therefore this type of calculations is not yet on offer.

MUDr. Eugen Jonáš,
Stella Jónášová, daughter

Calculations are devided into two types:

  A. small calculation          B. special calculation

and four groups:     

I.    Naturally infertile days – contraception

II.  Gender selection – a boy or a girl

III.  Optimal fertile days – problem to get pregnant

IV.  The dates of “good vitality" – a miscarriage,         complications

Calculation of Natural Conception Control can be ordered at one of the Centers Jonas, led him trained associates:

CENTRUM JONAS - main Center

Dr. Eugen Jonáš, Stella Jónášová
MAŇA, Slovakia
Dr. Stanislav Bílík, Csc.
Czech Republic



Fertility is the natural ability of men and women to reproduce. Women can get pregnant and men are able to father a child like a result of unprotected sexual intercourse during fertile days of woman.

Period between two menstruations (usually in the middle of the cycle) is considered as the most appropriate time for the conception. Then supposedly the mature egg is released by the ovary where it enters the fallopian tube and continues to the womb. As it comes to the conception, the fertilized egg is able to implant to the uterine lining. If no conception occurs, the uterine lining as well as blood will be shed and the unfertilized egg will be expelled during the menstrual bleeding.

Scientists found out that certain tribes living in Africa and Asia have sexual intercourse exclusively during the time when a woman has a menstruation. And these tribes reproduce just as fast as any other people on the Earth.

Dr. Eugen Jonas argued that from the very beginning of his research, namely that the conception can happen at any time during the cycle.

Natural conception control apart the fertile days according to the period, considers another cycle of fertile days, which is based on the biorhythm that Dr. Jonas determines for each woman individually.
According to the results of the 35 years of research (1956 – 1992), 85% of the conceptions occur right during this biorhythm fertile period.

Further improvement of the method was introduction into special calculation and small calculation that offer four basic groups:

  1. Naturally infertile days – contraception (10%)
  2. Gender selection – fertile days for conceiving a baby boy or a baby girl (16%)
  3. Optimal fertile days – for women who cannot become pregnant, although they are healthy and able to have children – primary sterility – and their husbands are also able to have children.
    This type of the calculation is the most common (43%). Unfortunately, the infertility has an increasing tendency that is caused by several factors, e.g.: the use of hormones, improper lifestyle, pollution and so on.
  4. The dates of „good vitality“ – for women who have suffered a miscarriage or had an abortion or complications with the fetus or newly-born child, other complications, etc. The second most common type of the calculations (31%).
    Here are some factors that increase the risk of the complications e.g.: abortion, undergoing IVF- multiple pregnancies, premature labors, endometriosis, use of hormones, others.