Evidence Birth Research on Due Dates


The traditional way of calculating the estimated due date (40 weeks after the last menstrual period) is not evidence-based. Instead, it is more accurate to give women a range of time that they will probably give birth:

* About half of first-time moms will give birth by 40 weeks and 5 days after the LMP, with the other half giving birth after that time poin

*About half of moms who have given birth before will give birth by 40 weeks and 3 days after the LMP, with the other hal...f giving birth after that

*An ultrasound before 20 weeks is usually more accurate than using the last menstrual period, and the accuracy of an ultrasound is highest if it is done between 11 and 14 weeks

More information on the Evidence Birth page itself: Click: Evidencebirth.com