It is narrated from Sa'id bin al-Musayyib and 'Ubaydullah bin 'Abdullah that the Prophet (peace be upon him) said: "If she gives birth to a red, straight-haired child, then he belongs to her husband, and if she gives birth to a black and curly-haired child, then he belongs to the one upon whom the accusation was made." She gave birth to a black child.
Hadith Referenceمسند الإمام الشافعي / كتاب اللعان / 1336