Umayr bin Numayr says that Ibn Umar (may Allah be pleased with them both) was asked about a slave woman jointly owned by two men, one of whom has intercourse with her. He said: There is no hadd punishment on him; her value is to be charged to him and he takes her. (b) This may apply where she has become pregnant by him, and Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18296