due date

a due date is an estimate of when a pregnant woman will have her baby. it is calculated by taking the first day of her last menstrual period (lmp), adding 7 days, and then counting backward 3 months; or by adding 40 weeks from the first day of the last menstrual period (for women with regular 28-day cycles).

for example, using the first method, if a pregnant woman's last period started on march 20, add 7 days to get march 27 and then subtract 3 months to get a due date of december 27. using the second method, 40 weeks counted from march 20 is december 25.

ultrasound is often used to estimate a due date based on the size of the fetus.

the due date is only an estimate of when a woman will deliver. most women do not give birth on their due date, but they do within 2 weeks before or after.

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due date

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