Believe it or not, but when Nathalie was pregnant, we received 3 different estimated due dates and
the gaps between them were quite substantial. The problem was not so much that we had no clue
when our son was gonna be born. But knowing the expected due date fulfils a vital purpose and
because of that, it is very important that it is as accurate as possible. Exactly! So in this video, we are
first going to talk about what the purpose of the expected delivery date really is and why there is
normally only one reliable way to calculate it. And then afterwards, we are also going to discuss
why ultrasound exams later in your pregnancy normally lead to less accurate estimates of
the expected due date and what you need to do when you receive several dates! Yes!
This is Nathalie, a pregnancy and birth consultant and TCM therapist,
and that's Mathias a researcher and science geek and this is our channel on which we help mommies and
their babies naturally and science-based! So, let’s talk about due dates!
Alright, so, let us first start by saying that there is a lot of confusion about what is meant by
“estimated due date”. Estimated due date simply means the delivery date that would apply
IF your baby was born exactly 40 weeks after the first day of your last period.
However, this almost never applies. Obviously, babies can also be born for example after 39 or
41 weeks of pregnancy, right? Still, we wanna get the estimated due date as right as possible
not so that you know when your baby will be born. But in order for you to know when exactly you have
been 40 weeks pregnant. Yes. And that’s important because you - together with your doctor - are
going to make decisions based on that date, for example, if you should induce labor? Well,
that’s one thing to discuss if you are like 41 weeks pregnant, right? But what if they got your due
date wrong and you are actually only just 39 weeks pregnant? Well, in that case, things suddenly start
to look a bit different when you talk about the necessity of labor induction, right?
And because of that it is very important to get the expected due date as “right” as possible.
Right! Now, the most common way to calculate the expected due date is based on the first day of
your last menstrual period assuming that you had a 28 days menstrual cycle. If you know that date,
then you simply add 280 days. And the result is your expected due date. However, this calculation
is based on assumptions, the first one being what we just heard that you had a 28 days cycle. And it
also assumes that you ovulated exactly on day 14 which is why many doctors and midwives will adjust
your expected due date if your cycle was not 28 days. In fact, most online calculators allow
you to do that. We will link to one example in the description below this video. Right! Now,
if all the assumptions of the menstrual period approach are met, then this CAN be an accurate
approach of estimating your expected due date. But not necessarily, particularly, if things are not
very clear. For example, what if your cycle was irregular? What if you did not ovulate on day 14?
Also, many women just don’t know the first day of their last cycle or they are not 100% sure about
it. So, the question is: is there a more accurate way to determine your expected due date? And
the answer is “yes, there is”. And that would be an ultrasound exam if it is done within a certain
time frame of your pregnancy. In fact, there is a large scientific study from Finland which compared
the accuracy of the menstrual period approach that we just discussed with an ultrasound exam,
in terms of predicting the delivery date. And what the scientists found was that an ultrasound exam
sometime between week 8 and week 16 of a pregnancy is a more accurate way to predict
the estimated delivery date compared to the menstrual period approach. Now, you might be
tempted to believe that expected due dates which are based on ultrasounds later in your pregnancy,
are more accurate than when they are based on ultrasounds early in your pregnancy, because,
hey, they are closer to your due date, right? But that’s not the case. And here is why: Yes,
so when your doctor does an ultrasound exam, then they compare the size of your baby with like a
“standard size chart”, right? Now, early in pregnancy, all babies are about the same size. So,
they would just take that size, look at their chart and go: okay, baby is this size, so we can
expect the delivery date to be …, whatever, right? However, if you look at a school class, you are
going to see that not all children are equally tall, right? And this is basically what we
see in later stages of pregnancies. Right! Babies grow at different rates and at some point,
you can no longer compare the size of the baby to a standard size chart and then conclude from that
chart what should be the expected delivery date, right? Because what if your baby is simply taller
or smaller than the average baby at the same stage of a pregnancy? So, when exactly is then the best
time to have an ultrasound exam for the most accurate delivery date? Well in most countries,
we are not sure if it applies to every country, right? But in most countries, like Germany for example,
they normally base the estimated due date on the first ultrasound exam which is normally done
some time before or in week 12 of a pregnancy. And that date is normally cast in stone, not to be
altered at a later stage except maybe on very very rare occasions. Now, what you can do if they give
you like several estimated due dates? Because this is really a question that we receive very often!
Well, all you can do is talk to your doctor or doctors who gave you the dates.
With the background information that you now have, it will be easier to discuss this matter with your
doctor. Yes. So, don’t hesitate to address your concerns and find out why your date is constantly
being adjusted instead of going with the date that was first communicated since that date is
normally the most accurate one, right? And if you do that, we are sure that your doctor will gladly
give you a detailed explanation! Yes! We really hope that you have found our video helpful. If you did,
we would be super grateful if you could leave us a like! Yes! And for more useful tips and tools
on pregnancy and baby-related topics, make sure to subscribe to our channel and to hit the bell!