Aicardi J
Neurosciences Department, The Institute of Child Health, University College, London Medical School, England.
Semin Pediatr Neurol. 1998 Mar;5(1):15-20. doi: 10.1016/s1071-9091(98)80013-2.
Developmental delay includes mental retardation (IQ less than 70) and borderline intellectual functioning (IQ 71 to 84). The overall frequency is between 1% and 2% of the child population with most cases in the mild range (IQ 50 to 70). Severe mental retardation is mostly due to genetic or acquired biological causes. Mild retardation is more commonly of acquired causes, and in borderline intellectual functioning, sociocultural factors play a role in addition to biological factors. The main prenatal causes include chromosomal and nonchromosomal genetic conditions, metabolic disorders, and adverse events during gestation, whereas environmental factors (eg, alcohol) more commonly cause mild retardation.
发育迟缓包括智力障碍（智商低于70）和边缘智力功能（智商71至84）。总体发生率在儿童群体的1%至2%之间，大多数病例为轻度（智商50至70）。重度智力障碍主要由遗传或后天生物学原因导致。轻度智力障碍更常见于后天原因，而在边缘智力功能中，除生物学因素外，社会文化因素也起作用。主要的产前原因包括染色体和非染色体遗传疾病、代谢紊乱以及孕期不良事件，而环境因素（如酒精）更常导致轻度智力障碍。
