Demographic characteristics of the study populations.

HEU, HIV-1 exposed uninfected; N/A, Not available;aBetween-group comparison by Chi-square, t or Wilcoxon rank sum test, as appropriate.bSelf-reported ethnicity; if one parent reported a non-white ethnicity, that ethnicity was assigned to the child. Ethnicity is not reported for the HIV− group as no data were available for 99 of them. All Aboriginal/First nation/Metis/Inuit and 15/173 Black/African Canadian children were from the Vancouver site.cMaternal and paternal age data were known/available for 84/94 and 67/94 of HIV+ children respectively. Maternal and paternal age data were known/available for 177/177 and 136/177 of HEU children respectively.