Changes in uterine size after vaginal delivery and cesarean section determined by vaginal sonography in the puerperium

There have been few reports on postpartum changes in the uterus during the three months after delivery. The aim of this study was to evaluate uterine morphological changes in women after vaginal delivery (n=262-351) and in wo men after cesarean section (n=64-82) and to evaluate the relation between b reastfeeding and parity, and uterine involution at 1 and 3 months postpartu m measured by vaginal ultrasonography. There were no significant difference s in parity between the vaginal delivery group and the cesarean section gro up. The length of the uterus at one month (7.93+/-1.16 cm, mean+/-SD) and, three months (7.03+/- 1.19 cm) and the width of the uterus at three months (3.83+/-0.94 cm) after delivery in the cesarean section group were greater than in the transvaginal group (7.64+/-1.03 cm, 6.65+/-0.99 cm, 3.57+/-0.62 cm, respective ly). Increasing maternal parity was associated slightly wit h larger uterine size at one month post partum. The length of the uterus of women with a breast-feeding rate of 80% or more per day was 6.35+/-0.85 cm , and shorter than in women with a rate of 20% or less 7.03+/-1.04 cm, at t hree months after delivery. The width of the uterine body of women with a b reast-feeding rate of 80%, or more per day was 3.32+/-0.45 cm, and shorter than in women with a rate of 20% or less 3.87+/-0.66 cm, at 3 months after delivery. Stepwise regression and multiple regression analysis among parity , the history of cesarean section, the breast-feeding rate at one and three months after the delivery, and the restoration of the menses at three mont hs after the delivery showed that the uterine size at one month after the d elivery was related to the cesarean section and that the uterine size at th ree months after delivery was mostly related to the rate of breastfeeding. These results indicated that uterine involution was related to delivery mod e at one and three months postpartum, feeding mode at three months postpart um the menses restoration, and parity. The rate of breastfeeding was mostly related to the uterine size at three months postpartum.