Objective To probe into the relationship among the 4 items of blood coagulation with the childbirth fashions and the body weights in neonates.The clinical reference basis was provided to analyze the blood coagulation physiology and influence factors in neonates.Methods The 4 items of blood coagulation,which included prothrombin time (PT),activated partial thromboplastin time (APTT),fibrinogen (FIB) and thrombin time (TT),were determined in plasma for 644 neonates with different childbirth fashions and different body weights.Results Compared with control group,the 4 items of blood coagulation in the first groups (＜1500 g) of natural childbirth and caesarean section group for neonates with different body weights were all obviously extended (P＜0.01); PT,APTT was extended (P＜0.05) and TT,FIB was not apparently changed (P＞0.05) for second group (1500～2500 g),the 4 items of blood coagulation were all not apparendy changed (P＞0.05) for fourth group (＞4000 g).First group of to cut the belly open childbirth was compared with first group of natural childbirth,PT,APTT is extended (P＜0.05) and TT,FIB is not changed (P＞0.05).The 4 items of blood coagulation are not apparently changed (P＞0.05) for other corresponding body weights in caesarean section group and natural childbirth.Conclusions The 4 items of blood coagulation of neonates are affected by body weights.The smaller the body weights,the longer time of the blood coagulation.The blood coagulation times gradually shorten with the increasing body weight,but with FIB gradually increased.The childbirth fashions affect the blood coagulation neonates with the weight ＜1500 g.