Abbreviation: HC = Head Circumference 

a. Studies are sorted first by overall study confidence level then by Age at Exam. 

b. {Zhang, 2022, 9944433@@author-year} reported standardized results based on head circumference z-scores, while {Cao, 2018, 5080197@@author-year} reported mean head circumference data (in cm). 

c. {Cao, 2018, 5080197@@author-year} upper and lower bounds have been truncated. For boys, for Tertile 2 the bounds are [-1.23, 1.27] and for Tertile 3 the bounds are [-1.19, 1.24]. For girls, for Tertile 2 the bounds are [-0.79, 2.13] and for Tertile 3 the bounds are [-2.26, 0.88].