问题
单项选择题
The uterus returns to the pelvic cavity in which time frame（）
A. 7th to 9th day postpartum.
B. 2 weeks postpartum.
C. End of the 6th week postpartum.
D. When the lochia changes to alba.
答案
参考答案：A
解析：
The normal involutional process returns the uterus to the pelvic cavity in 7 to 9 days. A significant involutional complication is the failure of the uterus to return to the pelvic cavity within the prescribed time period. This is known as subinvolution.