Is it permissible to take back one's wife after divorcing her with a single pronouncement of divorce upon discovering her pregnancy, and what is her waiting period (iddah), and what is the formula for taking her back before and after childbirth?

If you divorced your wife with a single, unprecedented pronouncement, you may take her back as long as she is still within her waiting period (iddah (definition)). The waiting period for a pregnant woman ends upon her delivery. If she delivers her child before you take her back, she becomes irrevocably separated from you, and you can only take her back with a new marriage contract. The act of taking her back can be done through an explicit statement indicating the intention to return, or by intention combined with an ambiguous utterance, or by engaging in sexual intercourse with her. It is recommended to have witnesses for the act of taking her back.