Males are born in excess of females. This ratio (M/T=male/total births) is influenced by various factors. A recent study showed that M/T in the United States (US) is Asian or Pacific Islander>White>American Indian or Alaska Native>Black or African American. This study was carried out in order to ascertain whether there are M/T differences in different races in the US by birth order.
Monthly male and female live births by race and birth order for the entire US were obtained for 2007-2015 with birth order as 1-=6 for these races.
There were 36,499,163 births. M/T decreased with increasing sibling order for all races (pWhite Black or African American/American Indian or Alaska Native. The differences between adjacent means were all significant (almost all p