Calculate due date (PDD) by last monthly (online calculator)

All pregnant women are interested in exactly what day her baby will be born, so the question of how to calculate when it is time to give birth in the last menstrual period is very relevant. The last calendar number of menstruation is the starting point not only for the expected date of birth (PDD), but also for the gestational age, if calculated from the beginning of menstruation or conception. There are several counting methods that you can apply yourself or visit a doctor for more accurate information.

Using online calculators

The easiest and most modern way to calculate the due date by the last months is to use an online calculator on the Internet. In this program you need to enter the date of your period and the program will give you an answer. Some applications can simultaneously show how long the lady is.

These apps come with additional handy features. Depending on the expected day of ovulation and the time of intimate contact, the possible sex of the unborn baby may also appear in the result field. By day and month, it is easy to calculate which sign of the zodiac the baby will be born, as well as the choice of names suitable for the child according to the church calendar.

We bring to your attention a very simple online calculator. Enter your details below, click the calculate button and get your due date instantly:

The table below will help you calculate the gestational age by the last menstruation yourself:

For example:

1. The last menses were on March 28th. The due date is January 2.
2. Last menstruation - August 11. The due date is May 18.

The difference between the real term of gestation from obstetric

A normal pregnancy lasts 280 days or 40 obstetric weeks. Since many women make monthly notes on the calendar, what date came their period and had unprotected intercourse, they can independently calculate the period of conception. But during the reception of the gynecologist, it turns out that the date of birth, calculated by the date of the last menstruation, differs from the one calculated by the woman herself.

Why is this happening - to make it easier to calculate the day when the baby should be born and to indicate the gestation period in the medical record, doctors use the concept of obstetric weeks. The starting point is the first day of the last menstrual period. At this time, intense monthly bleeding had just begun, and the gynecologist had already considered that the lady was in position at that time. There is no need to be intimidated by this, even if the difference between obstetric and actual due date is 2-3 weeks. Each woman can take away a certain period of time from the period set by the doctor, especially if she knows exactly the date of conception, and be guided by the number received.

To calculate the PDR for the last monthly, you can use one of the options:

• add the first day of the last menstruation with the number 280;
• subtract 3 months from the starting date of the last menstrual cycle and add a week;
• add 9 months and another 7 days to the first days of monthly bleeding.

You can make out one of the ways with an example. If a woman's last menstruation began on March 20, 3 months should be subtracted from this date (it turns out December 20) and add another week (in the end it comes out on December 27).

This method of calculation is more suitable for girls who have had a regular cycle.

As the practice of obstetricians shows, labor rarely begins on a calculated date. Often there are deviations in one direction or another, due not to inaccuracy of calculations, but to the individual characteristics of the female body and the timing of fetal maturation. Already at 37–38 weeks, the fetus is fully ripe and ready to be born.

Calculation of the date of birth from the day of conception

To find out on what day to expect the baby's birth, you must first calculate the date of the expected conception by the last menstruation - this will be easy for women who monitor the cycle duration for at least six months before pregnancy.

With a standard cycle duration of 28 days, the moment of ovulation occurs on the 12-15th day. This number of days should be added to the start date of the last menstruation - this will make it clear the period of release of the egg into the uterine cavity. Then 280 days should be added to the resulting number - this is how the estimated day of the baby's birth will be revealed.

The signs that appear on the days of ovulation will serve as a good hint to a woman, you just need to pay attention to them:

1. Breast enlargement, nipple tenderness.
2. Increased libido - the level of estrogen rises in order for the body to perform the function of procreation.
3. Improving mood, boosting energy - on the days of ovulation, a woman feels more attractive than ever, as a result of which the number of intimate contacts increases.
4. Vaginal discharge of cloudy, whitish mucus is cervical fluid that drains from the cervix the uterus to help the sperm get to the genital organ and keep them high viability.
5. An increase in basal temperature - before the opening of the fertile window, in the first half of the cycle, it stays at the level of 36.3-36.7 ° C, and during ovulation it rises sharply to 37-37.3 ° C.

Many women make the mistake of believing that they managed to conceive on the day of sexual intercourse, even if it was the only intimate act during the month. Spermatozoa can survive in an acidic environment for 2–4 days, and the most persistent ones can survive up to 5–7 days and meet an egg after a certain time after sex. The calculation of the time of delivery in a particular case may turn out to be erroneous for several days, but nevertheless, the date of conception will become approximately known.

Determine the estimated due date using an ultrasound scan

The most reliable way, how to correctly calculate the estimated date of birth by the last month, is the ultrasound procedure, but it is important to pay attention to the period of gestation study. The first visit to an ultrasound specialist is recommended for women at 11-12 weeks of pregnancy. The doctor will definitely ask what was the date of the last menstruation in order to calculate the period in obstetric weeks and the date of the expected birth with an error of only 1-3 days.

The study carried out in the first trimester is very informative - it accurately determines the date and date of delivery, since at this time all embryos have the same size and level of development. The specialist will measure the circumference of the abdomen and head of the fetus, the distance between the bones, the volume of the chest and others parameters, will compare them with the date of the last critical days and give an opinion on when the woman is expected to be to give birth. In the second and third trimesters, the differences in the weight and growth of the fetus will be significant, therefore, an accurate determination of the date of birth can be expected only in the first 12 weeks.

At the first movement of the child

Earlier, when there were no ultrasound machines, women were taught to calculate the date of birth by the first movement of the baby in the womb. And to this day, gynecologists are sure to be interested in exactly when the expectant mother felt the baby's tremors in her stomach, writing down the number in the exchange card. But this is done not to find out when the baby will be born, but to assess the correct development of the fetus.

It is assumed that during the first pregnancy, a woman will feel a stirring at 20 weeks, which means that to calculate the time of the baby's birth, it is necessary to add the same interval to this number. Mothers pregnant with their second and subsequent children will feel the first movements of the baby earlier - at 18 weeks, it turns out that they need to add another 22 weeks to this period to calculate the date of birth.

This method is not accurate. Many women lead an active lifestyle and may simply not notice the beginning of the crumbs moving. In some expectant mothers, the baby's movements begin earlier or later due to individual characteristics, heredity and other factors. The only chance to accurately determine the day when the baby began to move is in patients who are in a hospital during pregnancy and adhere to bed rest.

Based on a doctor's examination

When a woman first visits a gynecologist with suspicion of pregnancy, the doctor, conducting an examination, notes an increase in the size of the uterus. In accordance with the degree of growth of the genital organ, a highly qualified specialist can easily determine the gestation period and set the estimated time of birth, even without an ultrasound scan. He will compare his observations with the period received from the day of the last menstruation, which the patient reported.

At 5 weeks, the uterus resembles a hen's egg in size. After another 3 weeks, it will look like a goose egg. Only during the first trimester, according to the size of the genital organ, it will be possible to determine the date and time of childbirth when viewed in a chair, then the volume of the uterus will change with different intensity for each woman.

Pregnancy test application

For the convenience of expectant mothers, tables have been developed for calculating the date of birth by the last months - they apply the Negele formula, where three months should be subtracted from the day of the last menstruation and added 7 days. Thanks to such tables, you can clearly calculate your own due date and not get confused.

Many women who do not like and do not understand how to apply such inventions prefer to use modern pregnancy tests to calculate the date of birth at home. There are several types of tests (inkjet, tablet, electronic), which determine the real time after conception and give the result on the screen of the device.

The convenience of such devices is that they calculate the gestation period from the moment of conception by the level of hCG in the urine. Knowing the real data on the age of the fetus, you can subtract the figure from 280 and get the day of birth, which will be much more accurate than that obtained as a result of examination in the gynecologist's chair.

Establishing an estimated due date is a guideline that cannot be 100% relied on. Normally, the process of childbirth can begin at 38-42 weeks and this is not a deviation. According to statistics, only 17% of girls give birth exactly on the date set by doctors, the rest have babies 1-2 weeks earlier or later.