STUDIES BASED ON THE MEDICAL BIRTH REGISTRIES OF NORWAY AND SWEDEN

这些研究集中在：1）吸烟对头部的影响 周长和宫内生长-特别是头部保留，2）大小 出生时，通过头围、顶踵长度和出生时 体重与胎龄和围产期死亡率的关系，3） 倾向于重复相似的出生体重和胎龄在随后的 同一母亲的怀孕结果，4）围产期死亡率， 与出生顺序和兄弟姐妹的大小有关，5）流行病学风险 早产的流行病学危险因素，6） 小于胎龄儿，7）多胎分娩对 围产期死亡率。

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.