Objective To evaluate the effects of the non-supine position and the supine position during the second stage of labor on delivery outcomes.Methods In total,642 singleton term primiparas in the Fourth Hospital of Hebei Medical University between January 2013 and March 2014 were divided into the non-supine position group (n=320),which included the lateral (n=204) and hands-and-knees position (n=116),and the supine position group (n=322) according to primipara's choice.Delivery outcomes in the two groups were compared using the Student's t test,Mann-Whitney rank sum test and the x2 test.Results The incidence of caesarean section was similar in the non-supine position and supine position groups [0.9％(3/320) vs 1.9％ (6/322),x2=0.438,P=0.508].Compared with the supine position group,women in the non-supine position group had a higher incidence of perineal lacerations grede Ⅰ [85.2％ (270/317) vs 65.2％ (206/316),x2=33.884],longer duration of the second stage of labor [48.0 min (31.0-78.0 min) vs 41.0 min (25.0 67.3 min),Z=-3.066] and greater blood loss after 2 hours of labor [240.0 ml (200.0-287.5 ml) vs 210.0 ml (160.0-260.0 ml),Z=-3.736],but a significant reduction in posterolateral episiotomies [5.3％(17/317) vs 23.4％ (74/316),x2=41.908],perinealedema [13.6％ (43/317) vs 21.2％ (67/316),x2=6.430] and meconiumstained liquor [20.8％ (66/317) vs 33.2％ (105/316),x2=12.356] (all P＜0.05).In the non supine position group,fetal heart rate showed fewer early decelerations,variable decelerations and late decelerations than in the supine position group [10.1％ (32/317) vs 17.1％ (54/316),x2=6.593; 2.8％ (9/317) vs 6.6％ (21/316),x2=5.079; 3.2％ (10/317) vs 7.6％ (24/316),x2 6.139; all P＜0.05,respectively].Conclusions The non supine position during the second stage of labor may improve delivery outcomes.