预产期可以用下面这个方法来推估：在怀孕10到11周的时候可以透过B超来精确地推算预产期，但是只有约4%的宝宝是在预产期那一天出生的。
First day of last period: (day/month/year) Average cycle length: (22 to 45 days) (standard 28 days) Average luteal length*: (9 to 16 days) (standard 14 days) Conception date: Due date: Age of the fetus:
