What is the ruling on a committed wife refusing to conceive without a legitimate Shar'i reason, despite her husband's desire and insistence, and her rejection of all attempts to persuade her?

Procreation is a right for both spouses together, and it is not permissible for one of them to prevent the other from it. It is a right for the husband and for the wife, and it is forbidden for the wife to refuse procreation and deprive her husband of it. Intercession (Tawassul) can be lawful, such as interceding through the names and attributes of Allah, or unlawful, such as interceding through the prestige of a created being.