How Due Dates Are Calculated
Naegele's rule adds 280 days to the first day of your last menstrual period. This assumes a 28-day cycle with ovulation on day 14. If your cycle is shorter or longer, your midwife or doctor may adjust the estimate.
Calculate your estimated due date from your last period or conception.
Naegele's rule adds 280 days to the first day of your last menstrual period. This assumes a 28-day cycle with ovulation on day 14. If your cycle is shorter or longer, your midwife or doctor may adjust the estimate.