Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
1- It is permissible that the fiancée and the fiancé agree to make a standard, non-genetic, pre-nuptial medical check, provided they observe Islamic manners in terms of confidentiality and causing no harms to either party.
2- It is forbidden to conceal a contagious sickness or an illness that significantly affects the spouse.
Upon deliberation of the research submitted regarding pre-marital medical checks, the European Council for Fatwa and Research (ECFR) reached the following resolution:
First: pre-marital medical checks have both advantages and disadvantages. They reveal diseases that may deter one from marriage. However, this revelation may negatively affect the future and the psychology of the carrier.
Second: pre-marital medical checks, including genetic testing are Islamically legal, though confidentiality must be always observed.
Third: There is no harm in stipulating a pre-marital medical check prior to marriage.
Fourth: It is permissible that the fiancée and the fiancé agree to make a standard, non-genetic, pre-marital medical check, provided they observe Islamic manners in terms of confidentiality and causing no harms to either party.
Fifth: It is forbidden to conceal a contagious sickness or an illness that significantly affects the spouse. If it happens and a spouse gets harmed or dies of this sickness, his/her spouse will be subject to punishments and compensations stated by the Shari`ah.
Sixth: A spouse is entitled to a court declaration invalidating the marriage if it is proved that his/her spouse is a carrier of contagious viruses or has a sickness that negatively affects the significance of marriage.
Almighty Allah knows best.
Source: ECFR Mobile App