It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that Sayyidah Umm Sulaym (may Allah be pleased with her) said: O Messenger of Allah! If a woman sees in a dream that her husband is having intercourse with her, must she take a ritual bath? He (peace and blessings be upon him) said: "Yes, when she sees the fluid." Then Sayyidah Umm Salamah (may Allah be pleased with her) said: O Messenger of Allah! Does that happen to a woman as well? He (peace and blessings be upon him) said: "Yes, may your forehead be covered in dust! Where else would the resemblance to the maternal relatives come from? May your mother weep for you! Whichever of the two fluids reaches the womb first prevails in the resemblance."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20300