Population Research Unit, Faculty of Social Sciences, University of Helsinki, Helsinki, Finland.
Research Institute of Human Development, Kyoto International Social Welfare Exchange Centre, Kyoto, Japan.
Pediatr Res. 2023 Dec;94(6):2105-2114. doi: 10.1038/s41390-023-02757-1. Epub 2023 Jul 29.
Low birth weight (BW) is associated with lower cognitive functioning, but less is known of these associations across the full range of the BW distribution and its components. We analyzed how BW, birth length (BL) and birth ponderal index (BPI, kg/m) are associated with school performance and how childhood family social position modifies these associations.
Medical birth records of all Finnish children born in 1987-1997 were linked to school performance records at 16 years of age (N = 642,425). We used population averaged and within-siblings fixed-effects linear regression models.
BL showed a linear and BW a curvilinear association with school performance whereas for BPI the association was weak. The strongest association was found for BL explaining 0.08% of the variation in school performance in boys and 0.14% in girls. Demographic, gestational and social factors partly explained these associations. Similar but weaker associations were found within sibships. The association of BL with school performance was stronger at lower levels of family social position.
BL shows a linear association with school performance and can explain more school performance variation than BW. At the population level, BL can offer useful information on intrauterine environmental factors relevant for cognitive performance.
Birth length is linearly associated with school performance in late adolescence and explains a larger proportion of school performance variation than birth weight. The association between birth length and school performance is stronger in families with lower socio-economic position. At the population level, birth length can offer information on the intrauterine environment relevant for later cognitive performance.
低出生体重（BW）与较低的认知功能有关，但对于 BW 分布及其组成部分在整个范围内与这些关联的了解较少。我们分析了 BW、出生长度（BL）和出生体质量指数（BPI，kg/m）与学校表现的关系，以及儿童时期家庭社会地位如何调节这些关联。
将 1987 年至 1997 年期间所有芬兰儿童的医疗出生记录与 16 岁时的学校表现记录相关联（N=642425）。我们使用了人群平均和同胞内固定效应线性回归模型。
BL 与学校表现呈线性关系，BW 与学校表现呈曲线关系，而 BPI 的相关性较弱。BL 的相关性最强，解释了男孩学校表现变异的 0.08%，女孩的 0.14%。人口统计学、妊娠和社会因素部分解释了这些关联。在同胞内也发现了类似但较弱的关联。BL 与学校表现的关联在家庭社会地位较低的情况下更强。
BL 与学校表现呈线性关系，并且可以解释比 BW 更多的学校表现变异。在人群水平上，BL 可以提供有关与认知表现相关的宫内环境因素的有用信息。
BL 与青少年晚期的学校表现呈线性相关，并且可以解释比 BW 更多的学校表现变异。BL 与学校表现的关联在社会经济地位较低的家庭中更强。在人群水平上，BL 可以提供有关与后期认知表现相关的宫内环境的信息。
