Race, season, gonadotrophin, and sex ratio.
D044383:Black People; D005260:Female; D006062:Gonadotropins / Q000097:blood*; D006801:Humans; D008297:Male; D011247:Pregnancy; D011272:Pregnancy, Multiple; D012621:Seasons; D012744:Sex Ratio; D014481:United States; D044465:White People; D001741:Black or African American
D006062:Gonadotropins