C. Multiparity. Macrosomic infants are 2-3 times more likely to be born to parous women.

产次经产妇生育巨大胎儿的可能性是初产妇的2-3倍。

The main causes of dystocia of vertex presentation were occiput malpresentation, macrosomic infant, uterine atony, abnormal pelvic and genital tract.

导致头位难产的主要因素依次为胎头位置异常、巨大儿、宫缩乏力、软产道及骨产道异常。