Musannaf Ibn Abi Shayba 13:1156

Abu Bakr narrated to us, he said: Muhammad ibn Fudayl narrated to us, from Zakariyya, from ‘Amir, that he was asked about a man who bought a slave girl and claimed that she was pregnant, but the one who sold her denied it. So they placed the slave girl in the hands of a neutral person until her pregnancy became apparent, but she died. He said: "If her pregnancy had not become apparent, then she is from the property of the buyer."