Fetal head circumference by week of pregnancy

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Fetal head circumference is one of the important indicators, helping to assess the development of the fetus, and find out the abnormal signs of the baby right from the time it is in the womb. This helps limit the risk of birth defects in babies, especially microcephaly.

1. Fetal head circumference index by week of pregnancy


Fetal head circumference is an important indicator, denoted as HC (Head Circumference), to help assess fetal development through each week of pregnancy, thereby helping to detect abnormalities early in the pregnancy. children can get it.
The doctor will evaluate the head circumference index and other important indicators of the fetus based on certain weeks of pregnancy, in order to check the normal level of development of the baby:
1st week of pregnancy - 4th week of pregnancy : at this time, the fetus is still a very small embryo. 4-7 weeks of pregnancy: The fetal index to note in this period usually includes the diameter of the gestational sac and the length of the rump. By the sixth week of pregnancy, the diameter of the gestational sac ranges from about 14-25 mm. The ultrasound results will show the length of the head and buttocks of the fetus at the seventh week of pregnancy. From the 12th week onwards: at this time, the fetal head circumference, the length of the femur and the biparietal diameter of the fetus are specifically determined. In general, these indicators are often different for each fetus, such as having a fetus with shorter femurs, or having a larger head circumference. These differences are more or less influenced by the genetic characteristics of the parents. If the index of fetal head circumference is within the allowable range, it is considered to have no abnormal signs.

2.Fetal ultrasound measurements

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Fetal ultrasound measurements can show how your baby is developing and help detect fetal abnormalities early. During pregnancy, many different ultrasound measurements may be taken. Fetal ultrasound measurements may include crown-Rump Length (CRL), biparietal diameter (BPD), femur length (FL), head circumference (HC), and bone diameter. occipital length (OFD), abdominal circumference (AC) and femoral length (HL), as well as estimated fetal mass (EFW).
Most pregnant women will have a baseline ultrasound at least around 18-20 weeks gestation. However, medical associations do not recommend routine ultrasounds during pregnancy. A level II ultrasound usually takes more time and scale than a level I ultrasound, but this depends on the particular medical facility.
Ultrasound in pregnancy can be done as a “routine” ultrasound, an anatomical ultrasound, usually between 18-20 weeks of gestation, or it is done for specific reasons which are often time dependent. pregnancy point. Ultrasound measurements are useful throughout pregnancy to determine your due date and find out if the fetus is developing normally.

3. Is the fetal head circumference abnormal?


Your baby's head circumference measurement can say a lot about your baby's health. One of the most important is to help detect birth defects, such as microcephaly.
Tật đầu nhỏ
Số đo vòng đầu của thai nhi tật đầu nhỏ giúp phát hiện dị tật bẩm sinh như tật đầu nhỏ

If the fetal head circumference is smaller than the allowed limit, this is really a concern. This condition has many different causes, including:
Fetal growth retardation Genetics: familial microcephaly Chromosomal abnormalities Gene abnormalities Encephalopathy Endocrine system abnormalities, such as hypopituitarism or thyroid encephalopathy Premature craniosynostomy severe intellectual impairment and convulsions, as well as reduced life expectancy. The usual incidence of microcephaly is about 1 in 7,000 births and has increased more than 20-fold in certain regions of Brazil.

4. How to diagnose microcephaly in fetus?


Fetal head circumference is measured during pregnancy through ultrasound and then compared with certain normal curves. Microcephaly is usually diagnosed when the fetal head circumference falls below 2 or 3, even more than standard deviations.
Here are some diagnostic tests to help find the underlying cause of your baby's abnormally small head circumference, including:
Chọc ối
Chọc ối giúp tìm ra nguyên nhân cơ bản dẫn đến chu vi vòng đầu nhỏ bất thường của thai nhi nhưng gây ra rủi ro sinh non cho thai phụ

Amniocentesis : this method is done through the use of a needle to collect amniotic fluid. The fluid sample is then examined to look for any infection, or chromosomal abnormalities. However, this is an invasive procedure, which can pose a risk of preterm birth, so it is considered the diagnostic option of last resort. MRI scan: also known as magnetic resonance imaging. This is a method that helps the doctor to assess the health status of the fetus through detailed images inside the mother's body. Thereby, helping doctors detect abnormalities in the structure of organs early and provide appropriate treatment. In addition, this is also one of the ways to help check brain structures for fetuses at risk of small head circumference. In order to protect the health of pregnant women and babies during pregnancy, Vinmec International General Hospital provides a package of maternity services as a solution to help pregnant women feel secure because of the companionship of the medical team. throughout pregnancy. When choosing Maternity Package, pregnant women can:
The pregnancy process is monitored by a team of highly qualified doctors Regular check-ups, early detection of abnormalities The Package Maternity package helps to facilitate convenient for the birthing process Newborns get comprehensive care

Please dial HOTLINE for more information or register for an appointment HERE. Download MyVinmec app to make appointments faster and to manage your bookings easily.

Reference source: srhr.org; babymed.com
This article is written for readers from Sài Gòn, Hà Nội, Hồ Chí Minh, Phú Quốc, Nha Trang, Hạ Long, Hải Phòng, Đà Nẵng.

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