What is the ruling on working as a gynecologist in a fertility clinic (IVF, intrauterine insemination) if a portion of the cases involve individuals who are not legally married [according to Islamic law], but are cohabiting and legally recognized as married?

Conceiving a baby through IVF is permissible under certain conditions. As for the marriage of non-Muslims, reference is made to their customs and what they consider a valid marriage among themselves, and it is not a condition for it to take place in a church. Sheikh al-Islam Ibn Taymiyyah and Ibn Qudamah affirmed that their marriages are valid and acknowledged, and Al-Sarakhsi cited the verse: "And his wife, the carrier of firewood" as evidence for the validity of their marriages.