SPAZ reduced LBW ( risk ratio [ RR ] : 0.74 , 95 % CI : 0.60-0 .91 , P = 0.005 ; absolute risk reduction ( ARR ) : 4.5 % , 95 % CI : 1.4-7 .6 ; number needed to treat : 22 ) , and preterm delivery ( 0.62 , 95 % CI : 0.43-0 .89 , P = 0.010 ) , and increased mean birthweight ( 41.9 g , 95 % CI : 0.2-83 .6 , P = 0.049 ) .