White women with 25-hydroxyvitamin D 50 nmol/L or greater compared with less than 50 nmol/L had a 68 % reduction in SGA risk ( adjusted risk ratio 0.32 , 95 % CI 0.17-0 .63 ) and nonobese women with 25-hydroxyvitamin D 50 nmol/L or greater compared with less than 50 nmol/L had a 50 % reduction in SGA risk ( adjusted risk ratio 0.50 , 95 % CI 0.31-0 .82 ) .