What is the ruling on “the Biological Clock” ?

Question 11I would like to inform Your Eminence that a new product called the “Biological Clock” was advertised in a magazine. The advertisement states:

The biological clock is the indicator of fertility. It helps you control birth and plan to get the desired gender of the child in accordance with the Hadeeth that reads: If the male fluid prevails upon the female fluid, the baby will be male, and if the female fluid prevails upon the male fluid, the baby will be female. Kindly, find it attached.

Your Eminence Muftee, my question is: Do these claims contradict Sharee`ah? Is it permissible to make use of such a clock? Does it really help in selecting the desired gender of the child? I hope that you will answer me. May Allaah guide you to what is good and right.

Answer: It is not permissible to use such a clock for the purpose mentioned above or to believe in it. Actually, all fetus-related affairs such as conception and gender of the fetus belong to the Ghayb which is known only by Allaah (Glorified and Exalted be He)... read more here.