Is it permissible to contract a marriage immediately after an illicit relationship (zina) without an intervening waiting period (iddah), and what are the implications for a marriage that was contracted in this manner after eighteen years and the birth of three children?

Regarding the issue of a woman's 'iddah (waiting period) due to illicit sexual relations (zina) before marriage, there is a difference of opinion among scholars. The consequences for a man who commits zina with a woman and then marries her without an 'iddah vary according to these two opinions: According to those who do not obligate an 'iddah, the marriage is valid, and the child is legitimate. However, according to the opinion that mandates an 'iddah, they are required to renew the marriage contract, and the child is considered legitimate because it resulted from an intercourse believed to be permissible.