Ritchie K, McClure G
Lancet. 1979 Dec 8;2(8154):1227-9. doi: 10.1016/s0140-6736(79)92343-2.
Perinatal epidemiologists no longer speak much of "prematurity". Instead the World Health Organization recommends that infants born before 37 completed weeks of gestation should be designated "preterm" and those of birthweight less than 2500 g "low birthweight". Both definitions have obvious drawbacks--the former because menstrual dates are often unknown or unreliable, the latter because it does not separate preterm from small-for-gestational-age infants. Whatever the classification of these small infants there is no dispute about their high mortality and morbidity; in the United Kingdom they account for over two-thirds of first-week deaths.
围产期流行病学家如今很少再提及“早产”。相反，世界卫生组织建议，妊娠满37周前出生的婴儿应被定为“早产”，出生体重低于2500克的婴儿为“低出生体重”。这两种定义都有明显的缺陷——前者是因为末次月经日期往往未知或不可靠，后者是因为它没有将早产儿与小于胎龄儿区分开来。无论这些小婴儿如何分类，他们的高死亡率和高发病率是毋庸置疑的；在英国，他们占首周死亡人数的三分之二以上。
