Estimation of due date 预产期估算
The due date, also known as the estimated date of confinement, is an estimation of when a pregnant woman will deliver her baby. While the due date is often estimated as a single date, it can be helpful to consider a range of due dates, since only early 4% of births occur on the estimated due date.
预产期即预估分娩日期，临床常用纳格勒法则：末次月经首日+280天（40孕周），月经周期偏移会微调预产期范围。