What is edd in pregnancy

EDD calculator helps you discover your Estimated Date of Delivery (EDD) with two different methods, compares the results for you.

Once you finally got that positive pregnancy test, the next thing on your mind must have been - when will the baby arrive?

There are two main techniques for obtaining the EDD. Both are common medical practice, and both are used in this Estimated Date of Delivery calculator. In essence, the first one is based on the date of your Last Menstrual Period, and the second one relies on the results of an Ultrasound (Ultrasonography, US) examination. With the EDD calculator, you can compare these two estimations and check if your baby is healthy.

To take advantage of all the functions of this Estimated Date of Delivery calculator, you will need the following data:

First day of you Last Menstrual Period (LMP);
Date of your last Ultrasound (US) examination;
Gestational age predicted by your last Ultrasound examination; and
The average length of your menstrual cycle.

Don't remember when your last period was? Try our period calculator!

The LMP method is older and is based on a simple equation. The second technique uses the result of an ultrasound examination, and is more complicated as it starts with ultrasound measurements of different parts of the fetus's body to roughly determine its age.

Upon providing all the data, you will receive two results: the fetus' LMP and US gestational ages. There might be a slight difference between them, which you shouldn't be worried about. However, if the disparity is significant, it might be a sign of a growth problem, or another severe illnesses. This issue is more severe the later the pregnancy is. You will find all the relevant details in the section below.

Update your pregnancy calendar!

This EDD calculator uses Naegele's rule:

EDD = LMP + 1 year - 3 months + 7 days

The rule assumes that all the months last 30 days, and the pregnancy lasts 280 days.

Despite its simplicity, it has a few limitations. If your periods are irregular, the result might be misleading. The same problem applies to women who do not follow their menstrual cycle, or who became pregnant right after their previous pregnancy.

Gestational age is determined with the use of ultrasound equipment. Your OB/GYN will gather the following data during your pregnancy:

First trimester

crown-rump length (CRL) - measures the length of the fetus, from head to buttocks.

Second trimester

the biparietal diameter - the width of the fetus; head;
head circumference;
fundal height;
the femur length; and
abdominal circumference - the circumference of the fetus' belly.

Third trimester

the biparietal diameter;
head circumference;
the femur length; and
abdominal circumference.

An ultrasound machine can find all of the data required to answer to the vital question: "how far along am I"? The information discussed above is compared with population statistics, which allows for the precise estimation of the fetus' gestational age. The more advanced the gestational age of the fetus, the lower the measurement's reliability.

When using the EDD calculator in pregnancy, we shouldn't carelessly redate the EDD in the third trimester, as different EDD dates in this period may be indicative of growth issues, and may require an in-depth diagnosis.

The Estimated Date of Delivery calculator supplies you with two different results - what does it mean if they're inconsistent?

A small difference between the two EDD is normal and shouldn't worry you.

If the difference is significant and you're in your first trimester, it indicates that you probably miscalculated your Last Menstrual Period date, or that the ovulation happened on a different day than expected. It's not uncommon among women whose periods are irregular.
If your first ultrasound check was during your second trimester, the general rule stays the same. Always consult your doctor about any doubts you may have!
A significant difference in the third trimester is called an IntraUterine Growth Restriction (IUGR). In most cases, this state is caused by growth naturally slowing down -smaller parents tend to have smaller children. In some cases, however, a decreased fetus growth rate may inform us of a pathological process taking place in the uterus, such as:

placenta insufficiency;
viral infection; and
genetic disorders.

Increased size of a fetus may be caused by the fact that the baby had taller parents, but may also be caused by:

a very large pregnancy weight gain; and
maternal diabetes.

Remember, if your check-ups are frequent, your doctor will be able to track your baby's development. This allows the physician to intervene immediately in case of any abnormality.

The American College of Obstetricians and Gynecologists released guidelines for redating EDD:

Weeks of gestation:	Discrepancy between LMP and US EDD that supports redating:
<9 weeks	More than 5 days
<16 weeks	More than 7 days
<22 weeks	More than 10 days
<28 weeks	More than 14 days
>28 weeks	More than 21 days

Keep in mind that the doctor must first rule out all the possible pathological processes!

Page last reviewed: 29 April 2021
Next review due: 29 April 2024

Estimated Date Of Delivery (EDD) Pregnancy Due Date Calculation is very common and one should me know about this phenomenon of LIFE .

In Health support and Guided Video , Dr. Manoranjan Mohapatra , Answers the Basic question on What is EDD and How It is calculated? He goes on describing EDD with numerous Calculation Methods and some of the Problems Pregnant Women Faces during these Gestation Period.

A Must Watch Video For all

What is gestation in English?

As per the Definition by Merriam-Webster it States

"English Language Learners Definition of gestation. : the time when a person or animal is developing inside its mother before it is born also : the process of development that happens during this time. : the process by which something (such as an idea) forms and develops." -- Gestation | Definition of Gestation by Merriam-Webster @www.merriam-webster.com/dictionary/gestation

Gestation, is the time of Period , during which one or more offspring develops inside a woman. Childbirth typically occurs around 40 weeks from the start of the last menstrual period (LMP).

Simply Speaking the Child birth Occurs just over 9 months as per the LMP

Gestation Period or Pregnancy is classified into three Stages or called as trimesters divided evenly into 3 months each

Fertilization leads to An embryo is the developing offspring during the first eight weeks

Months 1 - 3 Are The First Trimester (LMPUp To 12 Weeks)

Months 4 - 6 Are The Second Trimester, And (13 Weeks To The 27 Weeks)

Months 7 - 9 Are The Third Trimester. (28 Weeks To 40 Weeks )

Lunar Months

Prenatal development is often measured in lunar months. Each lunar month consists of 28 days, organized into four weeks of seven days each. That means a pregnancy is 10 lunar months long!

Naegele's rule

Naegele's rule is a standard way of calculating the due date for a pregnancy when assuming a gestational age of 280 days at childbirth. The rule estimates the expected date of delivery (EDD) by adding a year, subtracting three months, and adding seven days to the origin of gestational age. The result is approximately 280 days (40 weeks) from the start of the last menstrual period. Another method is by adding 9 months and 7 days to the first day of the last menstrual period.

Naegele's rule is named after Franz Karl Naegele, the German obstetrician who devised the rule. Naegele was born July 12, 1778, in Düsseldorf, Germany. In 1806, Naegele became ordinary professor and director of the lying-in hospital in Heidelberg. His Lehrbuch der Geburtshilfe, published in 1830 for midwives, enjoyed a successful 14 editions.

Here's the formula to calculate your Estimated Due Date using Naegele's rule :

Date of Last Menstrual Period + 7 Days + 9 Calendar Months = Date of Estimated Date of Delivery

Example:

LMP = 8 May 2019

+1 year = 8 May 2020

−3 months = 8 February 2020

+7 days = 15 February 2020

In the Video Dr. Manoranjan Mohapatra , describes the other options, to understand EDD , when the person forget LMP Date. In that scenario,

Gynaecologist & Obstetrician Doctors takes help of Ultrasonography. The machine gives the composite calculation using the bipartite diameter head circumference, abdominal circumference, and female length these

276 days for both ultrasound-estimated and LMP-estimated gestational age in a US study of 1867 singleton live births