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.