Relevance of twin data to intrauterine selection: special case of childhood cancer.
D000022:Abortion, Spontaneous; D004200:Diseases in Twins; D004314:Down Syndrome / Q000235:genetics; D005260:Female; D005313:Fetal Death; D006801:Humans; D007198:Indians, North American; D008297:Male; D009369:Neoplasms / Q000235:genetics; D011247:Pregnancy; D012641:Selection, Genetic; D012744:Sex Ratio