摘要Background:The one-step method was routine practices in China,scientific evidence to support this intervention is scarce.The purpose of this study was to observe the natural process of head-to-body delivery interval by waiting for at least one contraction (two-step) after head delivered in normal birth.Methods:From March l to March 30 in 2015 at Haikou Maternal and Child Hospital in China,normal vaginal birth with normal baby condition were recorded by video.Videotapes were transferred to computer then replayed and observed.Results:Ninety-two cases were enrolled in this study.The average head-to-body delivery interval by two-step delivery was 71.04 ± 61.02 s,(mean + 2 standard deviation =193.07 s,95％ confidence interval [15.65-229.15] s).Fifty-one patients (51/92,55.43％) were ＜60 s,41 patients (41/92,44.57％) were over 60 s.Shoulders delivered at the first contraction were 96.74％ (89/92),3.26％ (3/92) had delivered by the second contraction.Shoulders emerged from perineum were 71.73％ (66/92),15.21％ (14/92) transversely,and 13.04％ (12/92) emerged from under pubic arch.Babies cried before the shoulder were 31.52％ (29/92),cried after birth 52.17％ (48/92),and 16.30％ (15/92) did not cry after birth.Baby activities included as making faces,sucking,and bubbled from mouth and noses,and the lighter blue color of skin with good perfusion.Conclusions:The average time of head-to-body delivery interval was longer than 60 s by two-step delivery.Majority shoulders were delivered at the first contraction.Majority shoulders emerged from perineum rather from under pubic arch.The routine one-step method of shoulder delivery where the downward force applied is not necessary and is not the right direction.Baby's breath,making faces,sucking,bubble from noses and mouth,and the light blue color of the faces,all those signs during shoulder delivery indicated a normal live birth.