It is narrated from Sayyiduna Abu Ubaydah bin al-Jarrah (may Allah be pleased with him) and Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "If a pregnant woman kills deliberately, she shall not be executed until she gives birth to what is in her womb, and until arrangements are made for the (child's) care. And if she commits adultery, she shall not be stoned until she gives birth to what is in her womb, and until arrangements are made for its care."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17271