Groups did not differ significantly in mean birth length , length-for-age z score ( LAZ ) , head circumference , or percentage low birth length but differed in mean birth weight ( P = 0.044 ) , weight-for-age z score ( WAZ ; P = 0.046 ) , and BMI-for-age z score ( BMIZ ; P = 0.040 ) , with a trend toward differences in low birth weight ( P = 0.069 ) .