There are so many ways to calculate a pregnancy week and due date and yes I know that sometimes it confuses us a little but don’t worry here I am going to tell you the most common methods of calculating of due date in a very simple way-Calculation of due date from the first day of last menstrual period (LMP Method) a. Generally full term of a normal pregnancy is considered around 40 weeks (i.e.38 weeks from conception), so this is the most simple way to estimate your due date is to count 40 weeks, or 280 (40X7=280) days, from the first day of your last menstrual period (LMP). b. Another pretty solid way to know the due date is, to subtract three months from the first day of your last period and add seven days.
Imagine your last period started on September 15, you’d count back three months to June 15 and then add seven days, which means your due date would be June 22. Most doctors estimate due date with this formula too, but do remember here they use term ‘estimate’ so it is normal to deliver a week or two before or after.Calculation of due date from Conception date (the 266 days method)Calculating due date from the first day of last period works well for those women who have a relatively regular menstrual cycle. But if anyone has an irregular cycle, the LMP method may not work for one. A reliable estimated date of delivery (EDD) is important, so your doctor can use your conception date instead of your first day of last period.
Doctors add 266 days to your conception date and you get your estimated due date of delivery.Due date changed?Don’t worry! Your doctor may change your due date for some of these reasons as your pregnancy progresses-a. It may be that your periods were irregular and your early ultrasound dating was off.b. It may be that your first ultrasound was in the second trimester. c. It could also be because your fundal height is abnormal.d. Your levels of alpha-fetoprotein (AFP), a protein made by the baby, are outside the usual range. Hope you are in good touch with a good doctor! Good luck!!