Pregnancy dating by lmp helps process consolidating new memories
Naegele’s rule involves a simple calculation: Add seven days to the first day of your LMP and then subtract three months.
For example, if in the first trimester the ultrasound estimate falls within one week of the LMP estimate, we still use LMP to determine due date and length of pregnancy.Health-care providers define the stage or length of pregnancy differently than many people might think. Logically, one might imagine we represent a pregnancy by how much time has elapsed since conception.Instead, we most commonly date pregnancies from the first day of the last menstrual period (LMP).The expected duration of a pregnancy is 40 weeks from the first day of LMP (four weeks more than the traditional nine months by which many count).
Medical professionals consider delivery premature when it occurs before 36 weeks, and extremely premature when it occurs before 28 weeks’ LMP.
Read our report on the 13 best pregnancy i Phone and Android apps of the year here. Very few women actually deliver on their due date, so, while it’s important to have an idea of when your baby will be born, try not to get too attached to the exact date.