Department of Paediatrics, McGill University, Montreal, Canada.
Int J Epidemiol. 2011 Oct;40(5):1215-26. doi: 10.1093/ije/dyr094. Epub 2011 Jul 15.
Most studies of the associations between pre-natal or post-natal growth and cognitive ability have been based on children with pathologically slow growth measured between two time points only, rather than children with normal growth trajectories estimated from multiple measures of growth.
We investigated the associations of pre-natal and post-natal trajectories in both weight and length/height through the first 5 years of life with cognitive ability and mental health at 6.5 years of age among healthy children. Our study is based on 11 899 children who were born healthy at ≥37 completed weeks with birth weight ≥2500 g and had up to 13 measures of weight and length/height from birth to age 5 years and cognitive ability and behaviour measured at 6.5 years. Using a linear spline random-effects model with 2 knots at 3 and 12 months, we estimated growth trajectories for each child from birth to age 5 years in weight and length/height in four periods: gestational age-specific birth weight and length (pre-natal 'growth'), early infancy (0-3 months), late infancy (3-12 months) and early childhood (1-5 years). We used generalized estimating equations to estimate mean differences in IQ and mental health according to pre-natal and post-natal growth trajectory. IQ was measured using the Wechsler Abbreviated Scales of Intelligence, and mental health was assessed using the Strengths and Difficulties Questionnaire.
A 1 standard deviation (SD) in birth weight was positively associated with cognitive ability (0.82 IQ points, 95% CI: 0.54-1.10) after adjusting for confounders. For post-natal weight gain trajectories, a 1 SD faster weight gain was associated with an increase of 0.77 (95% CI: 0.42-1.11) IQ points for early infancy, 0.30 (95% CI: 0.02-0.58) points for late infancy, and 0.40 (95% CI: 0.04-0.76) for early childhood after adjusting for confounders and for earlier growth. For length/height trajectories, the magnitudes of increase in cognitive ability were similar to each other (~0.6 points) across the four periods. Pre-natal and infancy growth, but not early childhood growth, were associated with reduced externalising behaviours.
Although the effect sizes are small and residual confounding cannot be excluded, our results suggest that among healthy children, faster growth from the pre-natal period through age 5 years is positively associated with cognitive ability, whereas faster growth in the pre-natal period and infancy is positively associated with mental health at early school age.
大多数研究产前或产后生长与认知能力之间的关联都是基于仅在两个时间点测量的病理性生长缓慢的儿童，而不是基于多次生长测量估计的正常生长轨迹的儿童。
我们调查了健康儿童在生命的前 5 年中体重和身高/长度的产前和产后轨迹与 6.5 岁时认知能力和心理健康之间的关系。我们的研究基于 11899 名在≥37 周时出生健康且出生体重≥2500g的儿童，他们在出生至 5 岁时有多达 13 次体重和身高/长度测量值，在 6.5 岁时有认知能力和行为测量值。我们使用具有 3 个月和 12 个月处的 2 个结的线性样条随机效应模型，为每个儿童从出生到 5 岁的体重和身高/长度估计了四个时期的生长轨迹：胎龄特异性出生体重和长度（产前“生长”）、婴儿早期（0-3 个月）、婴儿晚期（3-12 个月）和幼儿期（1-5 岁）。我们使用广义估计方程根据产前和产后生长轨迹估计智商和心理健康的平均差异。智商使用 Wechsler 简明智力量表进行测量，心理健康使用长处和困难问卷进行评估。
调整混杂因素后，1 个标准差（SD）的出生体重与认知能力呈正相关（0.82 个智商点，95%置信区间：0.54-1.10）。对于产后体重增加轨迹，早期婴儿期体重增加 1 SD 与智商增加 0.77（95%置信区间：0.42-1.11）相关，婴儿晚期体重增加 0.30（95%置信区间：0.02-0.58），幼儿期体重增加 0.40（95%置信区间：0.04-0.76）。对于身高/长度轨迹，在调整混杂因素和早期生长后，四个时期认知能力的增长幅度相似（约 0.6 点）。产前和婴儿期的生长与减少的外化行为有关，但幼儿期的生长与减少的外化行为无关。
尽管效应大小较小，且无法排除残留混杂因素，但我们的结果表明，在健康儿童中，从产前到 5 岁的更快生长与认知能力呈正相关，而产前和婴儿期的更快生长与早期学龄期的心理健康呈正相关。
