A full-term pregnancy usually lasts anything between 40-41 weeks. While only 30 percent of pregnancies continue until the 40th week, most of them continue only till the 38th or 39th week.
So, how exactly is your due date calculated? Medical practitioners such as doctors’ and midwives count your due date from the first day of your last menstrual period i.e. LMP till the next forty weeks.
Considering the LMP day for calculating your due date is indeed a reliable option. This is because it isn’t possible to figure out the exact date or time when the sperm might have fertilized the egg as the entire process of fertilization might take anything between 24 hours to 5 days. Moreover, most women aren’t aware of when exactly they ovulated, but most of them keep a track of their periods.
So, rather than relying on an uncertain date to calculate your due delivery date, you have an almost near perfect date that can be considered as the onset of your pregnancy.
So, in a typical cycle, your LMP occurs around 2 weeks before you have conceived your baby, which means you are already through with two weeks of the estimated 40 weeks of pregnancy and almost 4 weeks by the time you have missed your periods. Now, all these figures might perplex you.
However, you need not get confused as all you need to do this is a simple calculation. To calculate the EDD (Estimated Due Date), you need to minus 3 months from the first day of your LMP and then add 7 days to it.
Yet another reliable method of calculating your EDD is through an ultrasound done between 6 to 9 weeks as it provides an accurate measurement of the developing fetus.
Usually, medical practitioners rely on both LMP, as well as an ultrasound method to provide you with an accurate date. Apart from this, practitioners may also take into consideration certain physical symbols such as height and size of your uterus, usually measured during every prenatal visit.
Whichever method you opt for, you can never get an absolute accurate date as it’s only your little munchkin who will decide when he/ she will arrive. Till then enjoy your pregnancy and keep waiting till your baby gets prepared to come out.