When you find out you are pregnant, one of the first things you want to know is the date of delivery. Since the exact date of conception is rarely known, it is necessary to learn how to calculate the date of delivery based on the last menstrual cycle that preceded the positive pregnancy test. However, this is a rough estimate, because only 5% of babies are born on the exact day. In any case, it is essential to have an idea of the period in which the baby should be born in order to evaluate its development and the progress of the pregnancy.
Steps
Method 1 of 3: Calculate Date Based on Last Menstrual Cycle
Step 1. Determine when your last menstrual cycle dates before conception
This method works best for women who have a regular cycle of around 28 days.
Step 2. Add 40 weeks to the date of your last period to determine the day of delivery
Generally, pregnancy lasts 9 months, or 40 weeks, which would be around 280 days from the last cycle.
Step 3. Alternatively, you can use Naegele's rule
Starting from the date of the last cycle, remove 3 months, add 7 days, then add a year. This way you will get the date of birth based on Naegele's rule.
Step 4. You need to use other methods if you don't remember the date of your last period or you have an irregular period
In these cases, it is more difficult to calculate the date of birth without any help. For a more accurate calculation, see your gynecologist and do an ultrasound to determine the baby's gestational age.
In any case, you can be able to make a rough estimate. Many women ovulate 14 days before menstruation begins. So, if your cycle is 40 days, you probably ovulated on day 26. If you know the day of ovulation, just add 266 days to determine the date of delivery in an approximate way
Method 2 of 3: Calculate the Date on Online Sites
Step 1. Search for an online site to calculate the delivery date
Do your research and choose the most reliable site.
Step 2. You must provide the date of conception or the date of the last period
It is often difficult to determine the exact date of conception, so many sites rely on the last cycle to make the calculation.
Method 3 of 3: Ask the Gynecologist to Calculate the Date
Step 1. Consult your gynecologist
Through the online sites you can get a rough idea of what the delivery date will be, but only the gynecologist can give you confirmation. He'll give you a transvaginal ultrasound to determine the exact date.
Ultrasound is the most accurate method of determining the date of delivery, especially if it is done in early pregnancy. In the following months it is useful for monitoring the development of the fetus, but it can no longer be used to understand the gestational age
Step 2. Be prepared for surprises
The date of birth is never precise, nor should it be: the baby will be born when it is ready and hopefully neither before nor after. It is almost always a mystery and, sometimes, the estimated date of delivery can change even during the pregnancy.
Advice
- A normal pregnancy can last from 38 to 42 weeks. Generally, an average of 40 weeks is estimated.
- Determining your due date is easy if you have a regular 28-day menstrual cycle. If you have an irregular period, you may want to see your gynecologist.
- In the event of a twin pregnancy, the date of birth may change. Generally, we do not reach the fortieth week and some gynecologists induce childbirth based on the development of the fetuses.
