Is it permissible for the husband to deprive his wife of childbearing for a long period, and is it valid to perform Istikhara to determine the time of conception?

Istikharah (prayer for guidance) has no place in the matter of procreation, as it is a primary objective of marriage and one of the five objectives of Sharia (definition) (preservation of progeny). Ibn Kathir and Ibn Ashour interpreted the Almighty's saying: "And seek that which Allah has ordained for you" [Quran 2:187] as referring to offspring, for the purpose of increasing the Ummah and ensuring the continuation of the species. The husband should be convinced of the benefits of having children in this world and the Hereafter.