title: Incidence of trisomy 18 in Sweden in 1981-1982: clustering in a small region.
mesh_terms: D002902:Chromosomes, Human, 16-18; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D013029:Space-Time Clustering; D013548:Sweden; D014314:Trisomy