There were no associations for changes in BMI-for-age z-score ( P = .40 ) , BF % ( girls 10-SY = -0.2 0.3 ; boys 10-SY = -0.1 0.3 ) , or menarche ( 10-SY hazard ratio = 0.91 , 95 % confidence interval = 0.83-1 .01 , P = .08 ) .