title: Twinning and Down syndrome.
authors: P
authors: P
authors: Doyle
mesh_terms: D004200:Diseases in Twins / Q000453:epidemiology / Q000235:genetics*; D004314:Down Syndrome / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008423:Maternal Age; D011247:Pregnancy; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology