产妇分娩是否顺利是由产力、产道、胎儿三因素决定的。临床上有的因诊断上的疏忽导致胎儿性难产,使手术助产、肩难产、产道撕裂、产后出血、新生儿锁骨骨折、新生儿臂丛麻痹及新生儿窒息等分娩并发症有所增加。可见产前准确地估计胎儿体重,对围产期保健具有重要意义。(1)影响胎儿发育的若干因素:①孕妇过度营养与减少活动量,对胎儿体重的增加起促进作用。临床发现 Whether the delivery of maternity is smooth is determined by the three factors of labor force, birth canal and fetus. Clinically, due to diagnostic negligence led to fetal dystocia, surgical midwifery, shoulder dystocia, birth canal tears, postpartum hemorrhage, neonatal clavicular fracture, neonatal brachial plexus and neonatal complications such as childbirth increased delivery complications . Visible prenatal accurate estimation of fetal weight, perinatal care is of great significance. (1) a number of factors that affect the development of the fetus: ① pregnant women over-nutrition and reduce activity, the increase in fetal weight to play a catalytic role. Clinical findings