The due date \u2013 the estimated date of arrival for your little one. Is it accurate? How is it calculated? Are ultrasounds accurate? You probably have a lot of questions about this even as you approach your due date. In this blog, we hope to give you a bit more information about all things due date.<\/p>\n
Got some questions? Then let\u2019s get going.<\/p>\n
Before we get into the \u201cwhat ifs\u201d and the exceptions, let’s lay out what a typical pregnancy looks like. This is just to give us a baseline for how things will be explained to you by your healthcare professionals.<\/p>\n
A typical pregnancy is estimated to be 40 weeks in length (280 days or the more generally those nine months that most of us are used to hearing). The due date is then calculated based on the first day of your last period. So, this means that your estimated due date (emphasis on estimated) is considered to be 40 weeks and 0 days after the first day of your last period.<\/p>\n
A full-term pregnancy is considered to be\u00a039-40 weeks<\/a>. Basically, this is the point at which your baby has the best chance of being born happy and healthy.<\/p>\n This estimation method is based on something called\u00a0Naegele\u2019s Rule<\/a>\u00a0(derived from a German obstetrician\u00a0Franz Karl Naegele’s<\/a>\u00a0<\/strong>theory) which comes with some problems but generally gives a decent estimate.<\/p>\n The calculations are as follows:<\/p>\n – Determine the first day of the last period the individual had. (Say you)<\/p>\n – Count back three months from that date<\/p>\n – Then with this new date add one year and one week<\/p>\n – You now have your estimated due date<\/p>\n This can be simplified somewhat but adding seven days to the first day of the last period and\u00a0adding 9 months<\/a>. This however is a more modern interpretation of the Naeglele rule that may not be in any way what the original method intended. Some online calculators will even ask for a potential date of conception.<\/p>\n There are some issues with this method, whichever way around someone uses it. The most obvious being that is assumes every woman has a perfect 28-day cycle and that once they find out they are pregnant they would easily and accurately recall the dates of their last period or the potential date of conception. It really is an estimate.<\/p>\n The alternative to using this rule is through the use of an ultrasound. Ultrasounds are more accurate of course but they aren\u2019t entirely fool proof as there is still room for error. You will get your best estimate within your first trimester if you are using an ultrasound.<\/p>\n