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The Jonas Method of birth control

Part of “Pseudoscience A to Z”, a series of articles in the Skeptics Canada newsletter.

The Jonas Method of natural conception control is a strange mix of quack medicine, religious inspiration, and an astrologically based pseudoscience called cosmobiology. If you believe the claims it enables seemingly infertile women to conceive, while promising that you can choose the sex of the child you wish. It also avoids miscarriages, and “eliminates birth defects and mental retardation”. All of these purported benefits are based on conceiving at just the right time.

The story of Dr. Eugen Jonas begins in Hungary during the 1950s. A practising Catholic, he was aghast that the communist government had legalized abortion, and he decided that something must be done to ensure that every child was wanted, and was born healthy. This was a noble idea to be sure, but it does not appear to have been tackled with scientific rigour and healthy skepticism. His personal history, as told on his web site, says he remembered that there were laws governing the fertility cycle that were known to the ancients, and he set about to rediscover them. The web site considers it significant that he discovered the conception rules on August 15, 1956, the Feast of the Assumption of Virgin Mary.

What is this wondrous knowledge? As befits a web site which is trying to sell something, the exact method is only vaguely described, but it appears to involve a second fertility cycle – something that was hitherto unknown (except to the ancients!). This cycle is separate from the normal menstrual cycle, which is based on astrology. Oops, sorry, that’s “cosmobiology”. After all, we are talking about a wacky kind of medicine here, and one good pseudoscience deserves another. Speaking of pseudoscience, there are also references to Dr. Jonas presenting his findings to the First National Conference on Biorhythms in 1964. Which nation they are talking about is not specified.

Some hints about the nature of the method can be found at a web site called, which is another example of why some people should not be allowed near a computer. They dedicate (waste?) a lot of bandwidth on the so-called lunar fertility cycle, but they do help us by providing more information about cosmobiology and the beliefs of Dr. Jonas. Differing from astrology, cosmobiology, as they explain it, is not concerned with interpreting the meaning of the positions of celestial bodies, but is “the demonstrable and physiological effects of certain planetary bodies.” Sounds like material for another article … but I’ve already done the letter C.

The secret to Dr. Jonas’ second cycle is revealed as a three-point plan. First, it doesn’t matter at which point in the menstrual cycle a woman is, her most fertile moment is when the Moon is at exactly the same phase as the time of her birth. So if she was born when the Moon appeared, say, 58% illuminated, then she waits until that point in the cycle and hubby gets lucky. From this we might conclude that he doesn’t need to splurge on champagne and start a crackling fire to get her in the mood: she’ll lunge at him as soon as Selene is just a bit past half full.

Whoa, not so fast big boy! Now it starts to get complicated. The second step says that to properly determine the sex of the child the Moon must also be in the same position as at her birth. So we need 58% illumination, and it has to be, oh, howzabout 7.4 arc-seconds east of Regulus. Now we’re getting somewhere! Or maybe not. Since the Moon doesn’t follow the ecliptic exactly, but also travels above and below it, we need to get the altitude as well as the azimuth. Looks like our poor husband has to wait a bit longer.

Once we’ve got that figured out all we need to do is ensure that step three is adhered to. That concerns the viability of the pregnancy and the fetus, and depends upon the positions of other nearby celestial bodies. How near isn’t mentioned on the web site.

Sounds like our love-lorn Lothario is better off letting the experts at the Centre Jonas International figure out his charts for him, for a mere 250 Australian dollars. Significantly more than the champagne, but will a bottle of Mumm’s ensure a perfectly healthy child of the sex of your choice?


Centre Jonas International:

3 responses to “The Jonas Method of birth control”

  1. Maria says:

    the website is not originaly dr. Jonas´s. Some crook woman has stolen his method and she is using his name. The calendars she make are not current…

  2. Jana Bujnova says:

    To whom it may concern, could you make an update in your history and geographical knowledge and notice that Mr. Jonas was born and is of Slovak nation. It is just next to by-you-known Hungary….

    • Oddfellow says:

      Actually, the correct spelling of his name is “Jonasz” which indicates he either was a Hungarian himself, or of Hungarian descent.

      Additionally, he was put in prison by the communists and died there.

      I read a little book describing his method in the 70’s.

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