STUDIES BASED ON THE MEDICAL BIRTH REGISTRIES OF NORWAY AND SWEDEN

这些研究主要集中在：1)吸烟对头部的影响 周长与宫内发育--尤其是保留头部，2)尺寸 出生时，通过头围、头跟长度和出生时间来测量 体重与胎龄和围产儿死亡率的关系，3) 有重复类似出生体重和胎龄的倾向 同一母亲的妊娠结局，4)围产儿死亡率 出生顺序和兄弟姐妹大小的关系，5)流行病学风险 早产因素，6)流行病学危险因素 小于胎龄儿出生，7)多胎生育对 围产儿死亡率。

These studies have focused on: 1) the impact of smoking on head circumference and intrauterine growth - especially head sparing, 2) size at birth as measured by head circumference, crown-heel length, and birth weight in relation to gestational age and perinatal mortality, 3) the tendency to repeat similar birth weight and gestational age in subsequent pregnancy outcomes to the same mothers, 4) perinatal mortality in relation to order of birth and size of sibship, 5) epidemiologic risk factors for preterm birth, 6) epidemiologic risk factors for small-for-gestational age births, 7) contribution of multiple births to perinatal mortality rates.