Should we adjust for gestational age when analysing birth weights? The use of z-scores revisited
Should we adjust for gestational age when analysing birth weights? The use of z-scores revisited
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DOI：
10.1093/humrep/dem151
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发表时间：
2007-08-01
影响因子：
6.1
通讯作者：
Temmerman, Marleen
中科院分区：
文献类型：
--
作者：
Delbaere, Ilse;Vansteelandt, Stijn;Temmerman, Marleen
出生体重是新生儿和婴儿死亡率和发病率的唯一最重要的风险指标，这就导致了一句成语：每一盎司都很重要。然而，由于种族、母亲和父亲的身高以及居住海拔等人口因素的不同，出生体重往往在不同人群中差异很大。因此，人们已经认识到，对出生体重的评估应依赖于其相对于背景人口出生体重分布的位置。这通常是通过标准化出生体重，通过其与给定胎龄层的人口平均值的偏差来实现的，这可以从人口定制的出生体重诺模图中获得。这一问题最近在《人类生殖》中被重新讨论，请求将出生体重报告为z分。在这篇文章中，我们认为，对胎龄等因素的调整可能存在于从受孕时暴露于[例如单胚胎移植(SET)或双胚胎移植(DET)]到出生体重的因果路径上，无论这种调整是通过分层、回归还是通过使用z分数进行的，都可能导致偏差。
Birth weight is the single most important risk indicator for neonatal and infant mortality and morbidity, which has led to the idiom that 'every ounce counts'. Birth weight in turn, however, tends to vary widely across populations as a result of differential fetal growth velocity with such demographic factors as ethnicity, maternal and paternal height and altitude of residence. Accordingly, it has been acknowledged that the appraisal of birth weight should rely on its position relative to the birth weight distribution of the background population. This is commonly done by standardizing birth weight through its deviation from the population mean in the given gestational age stratum, as can be obtained from population-customized birth weight nomograms. This issue was recently revisited in 'Human Reproduction' through a plea for reporting birth weight as z-scores. In this article, we argue that adjustment for factors, such as gestational age, which may lie on the causal pathway from exposures present at the time of conception [e.g. single-embryo transfer (SET) versus double-embryo transfer (DET)] to birth weight, may induce bias, regardless of whether the adjustment happens via stratification, regression or through the use of z-scores.