From the first day of your last period to your EDD, it takes about 280 days, or 40 weeks (LMP). Even though you probably didn’t get pregnant until about two weeks after your LMP, that day is still considered day one (fetal development lags two weeks behind your pregnancy dates).

How to Find Your EDD

A due date calculator will tell you when your baby is due. You can use the date of your last period or the date you found out you were pregnant to figure out when you are due. You can make plans based on your due date, and your provider can give you and your baby the best care possible. But that’s just a guess. Your due date might change, or you might give birth on a different day.

It’s not an exact science to figure out when you’re due. Even though it’s important to have an idea of when your baby will be born, try not to get too attached to the exact date.

Methods You Can Use To Calculate Your EDD

If your periods come every 28 days, there are two ways to figure out when you will give birth.

1. Using Naegele’s rule to estimate EDD

Naegele’s rule involves a simple calculation: Add seven days to the day your LMP starts, and then take three months away.

Here, If LMP is 20-06-2016;

+7 to the date

– 3 months 

+ 1 to the year

For our example, you’ve got 

EDD= 27th March, 2017

2. Using Pregnancy Wheel Method

You can also use a pregnancy wheel to figure out when you will give birth. This is how most doctors do things. If you have a pregnancy wheel, it’s easy to figure out when you’re due.

The first step is to look on the wheel for the date of your LMP. When you line up that date with the arrow, the wheel shows you when your payment is due.

Keep in mind that the due date is just an estimate of when your baby will come. It’s not likely that you will actually give birth on that date.

Easy Ways To Calculate Your Expected Day of Delivery (EDD)

3. Using an App

There are various applications both web and mobile apps that can calculate your estimated Due Date (EDD) effectively. This apps operates like the wheel method, where you put in your LMP and it brings out your EDD. They could also tell you your gestational age, i.e. how far gone your pregnancy is as at the time you are checking. Examples of these apps includes – DueDateCalculator, Medscape (for professionals only) can also calculate these and other health parameters, efficiently.

Calculating EDD For Women with Irregular Menstrual Cycle:

Some women’s cycles are always longer than the average of 28 days. In these situations, a pregnancy wheel can still be used, but you’ll need to do some simple math.The second half of a woman’s period is always 14 days long. This is the time between when a woman ovulates and when she gets her next period.

For example, if your cycle lasts 35 days, you probably ovulated on day 21.
Once you have a general idea of when you ovulated, you can use a pregnancy wheel and an adjusted LMP to figure out when you are due.

For instance, if your menstrual cycle usually lasts 35 days and your LMP was on June 1:Add 21 days (June 22).
Subtract 14 days from your LMP date to get your new LMP date (June 8).

After you figure out your adjusted LMP date, just write it on the pregnancy wheel and look at the date where the line crosses. That is when you should be done.
Some pregnancy wheels may let you enter the date of conception instead of your LMP. Conception happens within 72 hours of ovulation.

How To Calculate EDD for IVF Pregnancy

If you used embryo freezing and in vitro fertilization (IVF) to get pregnant, you can use the date of your IVF transfer to figure out when you will be due. If the embryos were transferred five days after the eggs were taken, add 261 days to the date of the transfer.
If your doctor transferred the embryos three days after getting your eggs, your due date is 263 days from now. On the day of your transfer, your provider will figure out when you’re due and tell you.

The Accuracy of Due Date Calculators

An estimate is all that a due date calculator can do. Your doctor will look at you and your growing baby to figure out when you are due. Your provider will do an ultrasound to get a better idea of when your baby will be born. During an ultrasound, the doctor or nurse takes measurements of your baby. These measurements help your doctor figure out how old your baby is in the womb and confirm when you are due.

The Importance of Knowing Your EDD

It’s important to know when you’re due so you can make plans. Knowing when you’re due helps you get ready to welcome your baby. You’ll have time to get ready for the hospital and get things like a car seat for the baby. If you already have other kids, having them count down the days until the new baby comes can help them get ready for the new addition.

You can also get the right prenatal care if you know when you’re due. This means taking prenatal vitamins and getting prenatal screenings at the right times during your pregnancy. During your pregnancy, your provider will also check your baby’s size and position to make sure it is growing well.

How To Calculate Your EDD without Knowing Your LMP

Talk to your provider if you don’t know when your last period was or when you got pregnant. They will do a scan, which will probably include a pregnancy ultrasound, to find out how far along you are in your pregnancy.

How To Calculate Your LMP from Your EDD

If you already know your due date and want to find out when you got pregnant, a reverse due date calculator can help. To find out when you got pregnant, just take 266 days off the date you were supposed to give birth. Most likely, you got pregnant around that time.

Twin Pregnancy Can Affect Your Delivery Date

Expecting twins or triplets is different from expecting one baby in many ways, including the due date. If you’re having more than one baby, your doctor will use the date of your last period and an ultrasound to figure out when your babies will be born. But each pregnancy is different, and your doctor may suggest that you give birth before the estimated due date. Talk to your doctor about when you might give birth to twins or triplets.

Note That-

  • A due date calculator might not always be right. 
  • This is especially true if you aren’t sure when your last period was, if your periods don’t come on time, or if you don’t know when you got pregnant. 
  • To find out when you’re due, you should see your doctor for a more accurate test, like an ultrasound.