A fortune cookie of a different kind.
The Chinese conception calendar is supposed to be able to predict the birth of the unborn child with a surprisingly high probability. It is based on calculations made by Chinese scientists in the 13th century. On the basis of the age of the mother with the fertilization of the ovum and the generation month the sex of the baby is to be predicted to be able. Like a multitude of other old wisdoms about women such as baking powder or wedding ring tests, guessing the sex with the Chinese conception calendar is mainly fun and should not be seen as 100% accurate.