| Outline Intoduction Calculated from the day of ovulation [gestational age after fertilization] Calculated from the first day of the last menstrual period [fetus age after menstrual period] How to Calculate Expected Date of Birth [Nagel Approximate Method] How to Calculate the Number of Weeks Pregnant When You Don’t Know the Date of Your Last Period or Irregular Period How many weeks pregnant should you take a pregnancy test? Pregnancy and Birth Categories by Number of Weeks of Pregnancy Like the number of weeks of pregnancy, it is used to count the progress of pregnancy by dividing it into early, middle and late stages. Pregnancy category Birth Grade Questions about calculating the number of weeks of pregnancy Summary |
Intoduction
Many expectant mothers who know they have a new life in their womb will count the days in anticipation of the day they will deliver the baby.
However, in some cases, there are also cases where people suspect that the expected number of pregnancy weeks told by the doctor and the expected date of delivery are different.
It is a good idea to learn how to calculate the number of weeks of pregnancy to get an idea of the rate of growth of the baby in the mother’s body and belly.
In this article, we will also explain how to calculate the due date and divide it by the number of weeks of pregnancy. Parents who want to know how many weeks of pregnancy are there, please refer to this.
How to count the weeks (months) of pregnancy
Gestational week is the unit that counts during pregnancy. There are gestational weeks and gestational months to count the progress of pregnancy.
Here is what you need to know: The weeks of pregnancy are complete, the months of pregnancy are numbered means that.
In short, day 1 of pregnancy would be week 0 of pregnancy and day 1 would be month 1 of pregnancy.
Based on these principles, I will explain the concepts of “gestational age after fertilization” calculated from the date of ovulation and “gestational age after menstruation” calculated from the first day of the last menstrual period.
Calculated from the day of ovulation [gestational age after fertilization]
However, to calculate post-fertilization gestational age, the date of ovulation must be determined. This is a counting method that can only be used when the ovulation date has been confirmed using basal body temperature or ovulation test drugs, so it cannot be called a very general counting method.
Therefore, in many cases, the number of weeks or months of pregnancy is calculated based on the postmenstrual age below.
Calculated from the first day of the last menstrual period [fetus age after menstrual period]
Postmenstrual age is a method of calculating the number of weeks of pregnancy from the first day of the last menstrual period prior to conception.
In this case, note that the first day of menstruation is considered day 0 of pregnancy week 1, not the day the period ends.
It is currently used as a major calculation method in medical institutions because it can be calculated as long as the menstrual period just before the pregnancy is detected is known.
How to Calculate Expected Date of Birth [Nagel Approximate Method]
If you know how many weeks pregnant you are, you can also calculate your due date.
Normally, the gestation period is 10 months (40 weeks 0 days of gestation).
It is not just a matter of counting the days. The calculation is a bit complicated considering the menstrual cycle is 28 days and converting it to 1 month.
This is where the Naegele approximation method comes into play.
The Naegele approximation method calculates the expected date of delivery as follows:
- If last menstrual period is from January to March then birth month +9
- If last menstrual period is after April 3
- date of birth+7 on the first day of the last menstrual period
You can calculate your due date using the above method.
■ (Example) If January 1st is the first day of your last period
Birth Month…1+9=October
date of birth…1+7=8th
Possible date of birth…October 8
■ (Example) If April 1 is the first day of the last menstrual period
Birth month: 4-3 = January
Date of Birth: 1+7 = 8th
Expected date of birth: January 8 (next year)
You can easily calculate the expected delivery date, so if you know the first day of the last period, why not try to calculate it?
How to Calculate the Number of Weeks Pregnant When You Don’t Know the Date of Your Last Period or Irregular Period
The counting and calculation methods introduced so far are based on the concept of a person having a 28-day menstrual cycle. Therefore, if the menstrual cycle is not 28 days, an error will occur.
In addition, people who do not know the first day of the last period due to an unstable menstrual cycle cannot calculate the number of weeks of pregnancy.
In such a case, an echocardiogram will determine the number of weeks pregnant from the growth and size of the baby in the abdomen.
If your menstrual cycles are not 28 days or you do not know the date of your last period, it is a good idea to first consult an obstetrician and gynecologist to determine how many weeks pregnant you are. .
How many weeks pregnant should you take a pregnancy test?
When calculating the number of weeks pregnant, I am concerned with the question, “How many weeks should I take a pregnancy test?”
There are several pregnancy tests that can be tested 4 weeks after the first day of the last period. Its purpose is to detect a hormone called human chorionic gonadotropin (hCG) which is secreted only during pregnancy.
Although there are individual variations, if you are pregnant the norm of hCG release that can be detected by test medication is after the fourth week of pregnancy.
However, pregnancy tests alone cannot detect an abnormal pregnancy such as an ectopic pregnancy. Normal pregnancy can be determined only after confirming the position of the fetus by ultrasound etc.
When calculating the number of weeks pregnant, I am concerned with the question, “How many weeks should I take a pregnancy test?”
There are several pregnancy tests that can be tested 4 weeks after the first day of the last period. Its purpose is to detect a hormone called human chorionic gonadotropin (hCG) which is secreted only during pregnancy.
Although there are individual variations, if you are pregnant the norm of hCG release that can be detected by test medication is after the fourth week of pregnancy.
In the event of an abnormal pregnancy, the mother’s body is also at great risk. For this reason, even if pregnancy is detected by over-the-counter pregnancy tests, be sure to get a pregnancy test done by an obstetrician and gynecologist as soon as possible.
Pregnancy and Birth Categories by Number of Weeks of Pregnancy
Like the number of weeks of pregnancy, it is used to count the progress of pregnancy by dividing it into early, middle and late stages.
In addition, as parturition approaches, there are also divisions for each birth period.
Next, let’s take a look at the categories of pregnancy and childbirth that you should know along with the number of weeks you are pregnant.
Like the number of weeks of pregnancy, it is used to count the progress of pregnancy by dividing it into early, middle and late stages.
In addition, as parturition approaches, there are also divisions for each birth period.
Pregnancy category
The first trimester is from 0 to 15 weeks (1 to 4 months of pregnancy) during pregnancy. The 16th to 27th week of pregnancy (5th to 7th month of pregnancy) is the second trimester. A pregnancy of 28 weeks or more (8 months or more of pregnancy) is called the third trimester.
For those who want to know the characteristics of each pregnancy category, please refer to the following.
Birth Grade
When it comes to the birth of a child, there is a division, and the period when the child grows well in the womb and becomes a body that can survive in the outside world is called full term. Based on this full-term duration, births before full-term are called premature births, and those that exceed full-term duration are called overterm births.
Premature, full term, and postpartum gestational weeks are as follows:
| Premature birth | Pregnancy 22 weeks 0 days to 36 weeks 6 days |
| Full term | 37 weeks 0 days to 41 weeks 6 days |
| Postpartum period | 42 weeks to 0 days |
After the postpartum period, the baby becomes too large and it becomes difficult to give birth naturally, or it becomes difficult for the baby to spend time in the womb.
Questions about calculating the number of weeks of pregnancy
Finally, I will explain the question of how to count the number of weeks of pregnancy (months of pregnancy).
2-3 weeks pregnant and not pregnant
When calculating the number of weeks of pregnancy, the menstrual cycle is counted as 28 days. Since the first day of the last menstrual period is the first day of week 0, no implantation or even ovulation actually occurs during this period.
Pregnancy is established only after the fertilized egg has implanted, but when calculating the number of weeks and months of pregnancy, periods of no pregnancy are also counted retrospectively.
Date of intercourse is not the date of conception
A common miscalculation of the number of weeks pregnant is that the date of intercourse is assumed to be 0 weeks 0 days pregnant.
Just because you have sex around the time of ovulation doesn’t mean you will be fertilized that day. Also it is said that it is difficult to identify the fertilization date in modern medical science.
When counting the number of weeks of pregnancy, the last menstrual period begins on day 0 week 0 (day 1 day 0 week 1). This is also important in terms of managing changes in a woman’s mind and body caused by hormones. There is information, so it is recommended that you get into the habit of recording your basal body temperature on a regular basis.
0 Month pregnancy not present
The weeks of pregnancy are counted in weeks and the months of pregnancy in full moons. For this reason, in the early stages of pregnancy, expressions such as “0 week 1 day” are used, but “0 months pregnant” is not.
0 week 1 day to 3 week 6 day is 1 month pregnancy, and 4 week 0 day to 2 month pregnancy.
Pregnancy period is not 10 october
Many people imagine October 10 when they hear the word pregnancy. For this reason, there are many people who suspect that the expected date of delivery as stated by the hospital etc. does not match with the expected date of delivery, even if 10 months and 10 days are added to the number of weeks. pregnancy.
October 10 is a term that was used as a guideline for pregnancy when perinatal medicine was not as developed as it is today.
In addition, there is a theory that it did not represent 10 months and 10 days, but was set at 10 months plus 10 days because first births were often later than expected.
In modern times, 10 months (280 days) is considered a guideline for gestation period, assuming that a month is of 28 days, which is the menstrual cycle.
2% Chance of giving birth on due date
Some mothers and fathers think that the baby will be born on the same day when calculating the due date from the number of weeks of pregnancy, but this is only a guideline.
It is said that the chances of the baby being born exactly on the due date are around 2%.
Also, even if the baby is less likely to be born on the expected date of birth, many still think that the baby will be born within a few days.
Actually, this is also not a certainty, and the results of a survey on the number of weeks of childbirth (*) show that most mothers give birth at 38 weeks.
This is because when calculating the number of weeks of pregnancy, the 28 days of the menstrual cycle are converted into one month.
Of course, the longer the menstrual cycle is more or less than 28 days, the greater the error.
Use the expected date of delivery only as a guide, and look forward to the day the baby is born and take care of the baby with confidence.
Summary
The number of weeks and months of pregnancy is also important to live according to the duration of pregnancy. It is important to know how to calculate and calculate correctly.
Know the correct number of weeks of pregnancy and how to calculate it, and live a healthy life that suits your baby and its timing.