Last menstrual period is April 12, and the due date is January 19 of the following year for regular menstruation, while for irregular menstruation, it should be calculated according to the ultrasound results in early pregnancy. The expected date of labor is calculated from the first day of the last menstrual period, and is generally calculated using the month -3 or +9 and the date +7. If a woman has irregular periods or cannot remember the time of her last period, she can calculate her due date from the ultrasound of the first trimester. Generally speaking, the expected date of labor is also an estimated date, in the expected date of labor a week earlier or later are within the normal range, usually recommended to do a good job of regular obstetric examination, if there is any abnormality recommended timely medical care.