Head circumference SDS characteristics in the total study population and by level of maternal education (n = 3383).

HC  =  head circumference, SDS  =  standard deviation score.
aValues are calculated with ANOVA for continuous variables and reflect means (SD) per educational level.

HC 即头围（head circumference），SDS 即标准差评分（standard deviation score）。标注为a的数值针对连续变量采用方差分析（ANOVA）计算得出，其反映了各教育水平下的均值（标准差）。