1. Assuming that their sexual relationship had been illegal according to Shari’ah law and that the woman had conceived before legal marriage, the child is illegitimate by birth. However, the child is not different from other children in all matters except inheritance.
2. In case, however, the said woman and man had sex after marriage contract and they do not know whether the child had been conceived before the marriage contract or after it, the child is treated as a shubha child [i.e. one who is born by mistake]. For further information in this regard, you can refer to index 8350 (site: 8493) (Children in Extramarital Affair) on our website.
Appendix:
We have forwarded the same question to the offices of some of the grand jurists (maraje’) and the answers which we have received are as under:[1]
Grand Ayatollah Khamenei (may Allah grant him long life):
Given the supposition made in the question, if they did not know the Islamic law [about extramarital affair], the child is treated as a shubha child; otherwise the child born to them is treated as an illegitimate child.
Grand Ayatollah Sistani (may Allah grant him long life):
The child is illegitimate by birth and he/she is not different from other children in all matters except inheritance.
Grand Ayatollah Makarem Shirazi (may Allah grant him long life):
If a man commits adultery with a woman who is not in a [marriage] contract with another man, it is permissible for him to marry her and if a child is born to them and it is not known whether it is from halal or haram sperm, the child is considered to be legitimate by birth.
Grand Ayatollah Saafi Gulpaigani (may Allah grant him long life):
The child is not treated as legitimate but other rules regarding child-father relationship are applicable to him/her.
Ayatolllah Mahdi Hadavi Tehrani (may Allah grant him long life):
If conception takes places before legal marriage, the child is illegitimate by birth.
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