The transplacental passage of fetal leukocytes into the maternal blood.
D005260:Female; D005331:Fetomaternal Transfusion; D005865:Gestational Age; D006801:Humans; D007621:Karyotyping; D007962:Leukocytes / Q000166:cytology; D008297:Male; D010298:Parity; D011247:Pregnancy; D012730:Sex Chromosomes; D012732:Sex Determination Analysis; D012737:Sex Factors