Every woman who is preparing to become a mother, with a certain degree of impatience, is waiting for the appearance of two strips on the test for determining pregnancy. And now, at last, the test shows a positive result! This is where the second wave of exciting experiences comes:
- How does the baby develop, normal or not?
- When should I go for ultrasound?
- And when will the future birth?
So, knowing the exact period of pregnancy, you can find answers to all of the above questions. Are you ready? We go further. ..
CONTENTS
Pregnancy, what is it?
Often, the confusion in the head of a pregnant woman arises from a misunderstanding of the essence of the term - "gestation period".Therefore, it is important to know when embryo development begins, and when the countdown begins before birth.
Look, the ovule after ovulation( exit from the ovary) lives about a day. This time is considered the most favorable for conception. At a menstrual cycle in 28 days the ovulation occurs on day 14.At the time of fertilization, the spermatozoon merges with the egg, and a week later the developing embryo is attached to the inner lining of the uterus.
Because most women have a variable length of the menstrual cycle, the exact date of ovulation and conception is not known to anyone. To solve this dilemma, all midwives of the world consider the beginning of pregnancy the first day of the last menstruation .After 9 months( 280 days) after this day, delivery should take place.
This is the paradox: the countdown of pregnancy has already gone, and conception was not yet. Therefore, the life of the embryo is less than the gestation period, on average, for 2 weeks.
Methods for determining the duration of pregnancy and the date of delivery
Of the existing methods for determining the duration of pregnancy and the possible date of delivery can be identified:
- ultrasound in the first trimester of pregnancy.
- The formula of Negele( according to the date of the last menstruation).
- Survey of a pregnant woman by a doctor( determining the size of the uterus).
- Evaluation of hCG level.
- Fetal movement.
All the world's doctors determine the gestational age for one basic parameter( ultrasound) and two auxiliary parameters( the date of menstruation and the examination of the pregnant woman).
Ultrasound examination
The main method is ultrasound. It is important to remember that the accuracy of this method is maximal in the first 10-12 weeks, and then it falls. Therefore, it is the first trimester ultrasound that is widely used to determine the expected date of delivery.
Modern devices can identify the fetal egg in the uterus as early as 3-5 weeks of pregnancy. As the embryo grows to 3-4 mm, it becomes possible to measure its KTP( coccyx-parietal size), which serves as the basis for determining the gestation period to within a day.
Usually in the conclusion the doctor specifies, what term he means: obstetric( from last менструации) or эмбриональный( from the moment of conception).
After the 22nd week of pregnancy, it is impossible to determine the exact age of the fetus.
But the measurement of its main parameters( head size, length of the femur, abdominal circumference) allows assessing the dynamics of growth. If it does not match the deadline for ultrasound in the first trimester, then there is a probability of fetal development retardation syndrome.
In addition, there are individual hereditary characteristics( low growth, large head), because of which in the third trimester, pregnancy can not be calculated by ultrasound.
Online calculator calculator - last menstruation date
Determining the gestation period on the day of the last menstruation is the most accessible way for a woman.
If the future mother is a happy owner of a regular cycle in 28 days, she can independently and accurately calculate the date of birth. For this, there are special formulas for Negele.
PRD = PMDP - 3 months + 7 days:
PDR - estimated date of delivery.
is the first day of last menstruation.
For example, if the MDP was on January 15, the DDP will be calculated as follows: January 15 -( minus) 3 months +( plus) 7 days = October 15 +( plus) 7 days = October 21.This is the basis for determining the date of birth in all special calculators for calculating the gestational age.
Enter the first day of the last monthly:
- Day.
- Month.
- Year.
Click the Calculate button.
The gestation period is determined by adding to the MDP the number of weeks that have elapsed since that day. Therefore, every woman can calculate the term of pregnancy using an ordinary calendar.
And if you can not determine the period for menstruation, what to do then?
The menstrual cycle is irregular .With a cycle exceeding 35 days, ovulation does not occur on day 14.Therefore, the formula of Negele will give an inaccurate result.
Receiving contraceptives .If the regularity of taking oral contraceptives is not observed, pregnancy may occur. Due to sudden ovulation, the formula for calculating PDR also does not fit.
In case of threat of early termination of pregnancy .It happens that there is a threat of termination of pregnancy at the very shortest possible time. Very often, it is manifested by scant bloody discharge in the days corresponding to the expected menstruation. That is, a woman can mix up bleeding at the 5th week of pregnancy and the usual menstruation, and will not even guess about her interesting situation. In such cases, the term is determined by ultrasound.
Medical Examination of a Pregnant
The placement of each pregnant woman in the women's consultation begins with an examination. The determination of the size of the uterus and the height of its bottom( that is, the upper part) can give an approximate information on the duration of pregnancy.
This method does not have 100% accuracy. After all, the individual location of the uterus, myoma and full bladder can make it difficult to examine. A multiple pregnancy is associated with a large increase in this body.
Hormone level of hCG
Already 8-10 days after conception, the B-subunit of hCG is determined in the blood of the expectant mother.
This hormone appears during pregnancy and doubles every 2-3 days. To judge the duration of gestation by its level can only be indirectly, because:
- The norms of HCG for every week of pregnancy have a large range.
- The level of the hormone increases with multiple pregnancy and some abnormalities of fetal development.
Therefore, it makes no sense to focus on this hormone when calculating the pregnancy period by weeks, when more accurate methods are available( ultrasound, for example).
Date of the first fetal movement of the fetus
It is believed that the pervious women feel the wiggling of the fetus from the 20th week of pregnancy. Repeated people can feel them already from 16-18 weeks.
In fact, it all depends on the individual characteristics of the mother and child, the thickness of the fat layer on the pregnant belly and on her desire to feel the tremors. In addition, often during the first movements take intestinal peristalsis. Therefore, do not rely on this indicator in calculating the gestational age.
When IVF, how to determine the duration of pregnancy?
With in vitro fertilization, many women doubt how correctly to count the weeks of pregnancy. After all, a developing embryo is being inserted into the uterus.
But regardless of the method of fertilization( by natural way, insemination of sperm or IVF), the gestation period is determined from the first day of the last month.
The only exception can be considered IVF with the protocol of suppression of menstruation( superlong protocol).In this case, the term is counted from the day of embryo replanting with the addition of two weeks.
Why do doctors need to determine the exact duration of pregnancy?
Here everything is very simple, accurate determination of the gestational age is applied:
- To assess the rate of fetal development.
- To determine the date of delivery.
- For screening for chromosomal mutations( Down syndrome, etc.).
- To determine the viability of a child in preterm labor.
The main goal of determining gestational age for a future mother is to adjust to the approaching birth of a baby and get acquainted with information about intrauterine development by weeks.
Source of publication: http: //zdravotvet.ru/ raschet-sroka-beremennosti-metody-opredeleniya-sroka-po-nedelyam /
