Objective:To investigate the effect on uterine involution in caesarean section.Methods:1230 cases of primipara were divided into group A(cesarean section

n=650)

group B(spontaneous delivery

n=580)

measuring the level of uterine fundus

descending speed of uterine fundus

observing the duration of lochia

routinely screening of uterine involution.Results:There was significant t difference between the two groups with regard to the average decending speed of uterine fundus within 5 days after delivery

group B was superior to group A;After 42 days

The cases whose lochia disappeared were 61.8%and 92.4%in group A and group B in turn;The day 5

30 and 42 ultrasound measurement of uterine volum

showing significant difference(P<0.05);Fluid accumulation in the cavity of uterus occurred in 38.2%

7.6%and uterine involution badly cases were 12.62%

8.62%in group A and group in turn(P<0.05);Conclusion:There are own rule on uterine involution after Cesarean section compared with spontaneous delivery

whereas still inferior to that of spontaneous delivery.We should control the indication of caesarean section and decrease unnecessary caesarean section.