Ali bin Abi Talhah narrates from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) concerning this saying of Allah Almighty: "And their husbands have more right to take them back in that (period), if they intend reconciliation" [Surah al-Baqarah: 228], that when a husband gives his pregnant wife one or two divorces, he has the right to take her back as long as she has not given birth, and it is not proper for the woman to conceal her pregnancy. Allah Almighty says: "And it is not lawful for them to conceal what Allah has created in their wombs" [Surah al-Baqarah: 228]. [Da'if]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرجعة / 15148