The long-term effect of breastfeeding on neurodevelopment was examined through a battery of neuropsychological tests in 1403 children ( 693 females , 710 males ; mean age 11 y 9mo [ SD 6mo ] , range : 10y 3mo-12y 8mo ) who were originally recruited at 6 to 12 weeks of age for a clinical trial on acellular pertussis vaccines .
