What is the ruling regarding a divorced woman who completed her waiting period (iddah) three months early due to breastfeeding and cessation of menstruation, then contracted marriage with another man, before discovering her pregnancy from her ex-husband?

The woman erred in calculating the iddah (waiting period) in months. The correct approach for a woman whose menstruation has ceased due to a known reason is to wait until it returns and then count her iddah by it, unless she reaches the age of menopause. The woman contracted her second marriage while still in the iddah from her first husband's divorce, rendering her marriage invalid. Ibn Qudamah said: "It is unanimously impermissible for a woman in her iddah to marry, based on Allah's saying: ﴿And do not determine to contract a marriage until the prescribed period reaches its end.﴾" This contract is void and has no effect, and she remains in the iddah of her divorce. Since she is pregnant, her iddah concludes upon delivery. Once her iddah is over, it is permissible for this man to marry her. Umar ibn al-Khattab, may Allah be pleased with him, said concerning any woman who marries during her iddah: "If her husband, the one who married her, has not consummated the marriage with her, they shall be separated, then she shall complete the remainder of her iddah from her first husband, and then the other man may propose to her like any other suitor."