Does conversation between a pregnant Muslim woman and a young Muslim man, and the تحديد ( تحديد could mean setting, specifying, or determining) of the mahr, constitute a marriage contract after the completion of the iddah (waiting period) due to childbirth, or must the contract be renewed?

A pregnant Christian wife whose husband is an unbeliever (kafir) must be separated from him if she embraces Islam. She is entitled to maintenance for her waiting period (iddah) until she gives birth, and she is also entitled to the full mahr (dowry). As for a woman married to a Muslim man who is still her husband, or who has been divorced by him while she is pregnant, it is not permissible to propose to her or marry her until she gives birth, as that is her waiting period. What the young man did by stipulating the dowry is an explicit proposal, which is forbidden during the waiting period, and therefore does not constitute a marriage contract. After the waiting period ends with childbirth, it is permissible to marry her if the conditions are met and there are no impediments.