Woman becoming pregnant before nikaah

If the woman marries the person who made her pregnant and the child is born before six months from the time of the nikaah, the child's lineage will not be established from the biological father. The child will be an illegitimate child and his/her lineage will be attributed to the mother.

However, if the child is born six months or more after the nikaah is performed, then in this case, the child's lineage will be established from the biological father and the child will not be regarded as an illegitimate child.

However, the man and woman should repent to Allah Ta'ala for committing this grave sin of zina before nikaah.

And Allah Ta'ala (الله تعالى) knows best.