Menstrual history Indirect measure of conception of roughly 280 days Reliability depends and influenced by - recall of memory - presence of light bleeding - regularity of cycles - OCP, breast feeding etc Nichols C. Most women may round off the dates or tell preferred dates May lead to misclassification as post term pregnancy Naegeles revisited 19th century Frederiech Naegele original article in German textbook Naegele himself credits Harmann Boerhaave with Inventing the formula for EDD. Comparison of pregnancy dating by last menstrual period, ultrasound scanning and their combination. 2002;160-1666 Methods of determining the gestational age Parameter variability 2SDIVF 1 day Ovulation 3 days IUI 3 days Single I/C 4 days 1st trimester examn 2 weeks2nd trimester examn 4 weeks3rd trimester examn 6 weeks Callen PW.
Its unclear whether 1st day of LMP or last day of LMP to be considered for EDD. Dating of pregnancy: Time to forget the last menstrual period.
The 21 Best Pregnancy i Phone & Android Apps of 2013 Calculating your due date isn’t an exact science.
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.
If you have regular 28-day menstrual cycles, there are two ways to calculate your due date.
From 27 weeks on the fetus finishes development and prepares for delivery.
Your health care provider might prefer to use the Development method, while another Midwife or Doctor may use the Gestation method.
I am sure they do that just to confuse pregnant women.
If you have no idea when your last period was, your doctor may order an ultrasound to determine your due date.
Some women have cycles that are consistently longer than the average 28-day cycle.