LMP (Last Menstrual Period) is the first day of the last menstrual cycle
EDD (Estimated Due Date) is calculated as 40 weeks, or 280 days, from the first day of the LMP
To calculate EDD, add 1 year, subtract 3 months, and add 7 days to the first day of the LMP
If the LMP is January 10, 2026, the EDD is October 17, 2026
If the menstrual cycle is longer or shorter than 28 days, adjust the EDD accordingly
For irregular periods, use an early ultrasound for a more accurate EDD
If ovulation date is known, add 266 days to estimate the EDD
LMP is used to estimate gestational age by counting weeks from the first day of the last period