How many weeks pregnant am I?

Beyond estimating the due date, calculating the weeks of pregnancy helps doctors to properly monitor the development of the baby and prepares mothers for changes in the body.

Last update: December 09, 2021

Estimating the weeks of pregnancy is no longer as complicated as it was years ago. Before, only symptoms helped in the calculation.

But now it is simpler. Common methods are ultrasound, a hormonal test with a conception indicator, or a special calculator. Traditional urine or blood tests also contribute to the count.

When you know the elapsed time, you anticipate a possible due date, you enable the doctor to monitor the baby’s development and understand the changes your body experiences.

Difference between weeks of gestation and weeks of pregnancy

The erroneous calculations are produced by the confusion between two terms: gestation weeks and weeks pregnant. The first ones are counted from when the baby begins to form, that is, about 2 weeks after the date of the last menstrual period (FUR), coinciding with the days the ovum was fertilized.

An article from the Los Angeles de Chimbote Catholic University states that gestation lasts 266 days or 38 weeks. But if you count in weeks of pregnancy, it would be from the first day of the URF until the birth, that is, 40 weeks.

Importance of the FUR

While there are advanced ways to calculate pregnancy time, knowing the FUR is essential for a more accurate account. Look on a calendar when your last period came down and count from 7 to 7, with every seventh day being a week of life for the fetus.

It is important that you do the calculation from the first day of the last period and not since you had sexual intercourse. Although it may seem like an insignificant piece of information, knowing the FUR is valuable for other procedures.

According to a publication in the journal Progress in Obstetrics and Gynecology, knowing when the last menstrual flow was facilitates medical interpretation of studies. In addition, with this date the ovarian cycle begins and specialists consider it when indicating contraceptives, prescribing ovulation treatments or for the control of menopause.

Knowing the menstrual cycle is essential for any woman, whether she is pregnant or not, whether she wants to have children or not.

Methods to measure weeks of pregnancy

To know the weeks elapsed in a pregnancy, we present the methods that are generally used by both doctors and mothers. Learn and practice them to be clear.

1. Last period

From the first day you spot in the last menstruation, count from 7 to 7 and the probable date of delivery will be when you reach 40 weeks.

2. Ultrasound

A fundamental part of prenatal control are ecosonograms. They allow to know the evolution from embryo to fetus.

Doctors use ultrasound to monitor the growth of new life and consider the due date. It is the ideal way to count the weeks when the patient had irregular cycles or if the FUR is unknown.

All ultrasounds are important, but first trimester evaluation is essential to determine chromosomal abnormalities and prevent obstetric complications. This is explained in a letter from the Anales bulletin of the Faculty of Medicine.

3. Date of conception

A regular cycle is, on average, 28 days. Being the day 14 that of ovulation. If you conceived on your fertile days and you know it exactly, count from there 38 weeks or 266 days to estimate the due date.

4. Hormonal test with indicator

Gonadotropin (hCG) levels in the blood increase in pregnancy. The value that indicates the laboratory test on hCG, guides as to the time in a state of pregnancy. The increase in gonadotropic hormone is up to weeks 10-12; then it stabilizes or decreases.

5. Pregnancy calculators

Gestational calculators are online or mobile phone applications where you enter your FUR and automatically compute the week you are in. Note that these programs only give an estimate and each pregnancy is different, so your result does not have to exactly match the date the baby will be born.

6. Height of the uterus

The height of the uterine fundus is a tool to measure the size of the fetus, exposes the Mayo Clinic. From this information, gynecologists establish your approximate pregnancy time.

After 24 weeks, the height of a baby’s fundus in centimeters tends to match the weeks of pregnancy. But this is not entirely accurate.

The weeks of pregnancy can be measured in different ways. You must know them, but it is also important that the doctor informs you.

Why is it important to know how many weeks pregnant you are?

Knowing precisely your weeks of pregnancy makes it easier for the OB / GYN to analyze prenatal evaluations, verify the health of the fetus, and anticipate any necessary procedures. The calculation also helps to address cases of premature birth and prevents the pregnancy from exceeding 40-41 weeks, accepted as normal.

In addition, you prepare for the transformations that you will experience in the process and you carry out procedures such as sick leave. Together with your doctor, you establish the diet indicated for the optimal development of the pregnancy, you make sure to what extent you can exercise without so many limitations and, the best thing, you get ready for the arrival of your child.

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