Fetal weight ultrasound is not accurate?

To estimate the weight of the fetus, obstetricians often use ultrasound method. Many pregnant mothers wonder about why it is necessary to determine the weight of the fetus and do not know whether fetal weight ultrasound is accurate.

So the estimation of fetal weight by ultrasonic method is accurate and not and the importance of predicting fetal weight for the birth process of pregnant mother? Invite you to find out with aFamilyToday Health in this article!

How doctors predict the weight of the fetus through ultrasound?

There are more than 30 different algorithms used to predict the baby's weight through ultrasound. The parameters will be collected from different locations and used to calculate the baby's size. Four parameters are commonly used to estimate the baby's size and weight:

Head circumference

Bipolar Diameter : This is the diameter measured at the largest cross-section from the baby's forehead to the back of the skull. Simply put, the dipole diameter can be understood as the diameter of the baby's head circumference. However, many babies are the same weight but have different bipolar diameters. So this parameter is not always reliable to estimate the baby's weight by ultrasound.

Abdominal Circumference: This can be considered as the most accurate parameter that reflects the baby's size.

Femur Length: The femur is considered the longest bone in the body. However, like the bipolar diameter, many babies have the same weight but have quite different femur length.

Other parameters such as baby's sex, gestational age, and other factors are also used in combination to derive a predicted baby's weight. For example, the babies of mothers with diabetes can be bigger due to their high blood sugar levels and several studies have shown that these babies will be larger than normal.

In addition to an ultrasound , a nurse or doctor can also predict the weight of the fetus manually when performing a prenatal examination using the Leopold procedure. This also helps determine the baby's position in the abdomen. However, this is not an accurate way to predict your baby's actual weight, although in some cases this method gives more accurate results than others.

Is fetal weight ultrasound accurate?

Ultrasound is an inaccurate method of determining the weight of the fetus. This method only helps to predict the baby's weight with an error of 8-15%, meaning your baby may be 8-15% heavier or lighter than the baby's actual weight.

The ultrasound is often more accurate when determining the size of the baby in the first half of pregnancy. At a later stage, each fetus develops in a different direction and the accuracy of the ultrasound at this time depends much on whether your baby is medium or small. The closer you get to the due date, the bigger your baby grows, and it's difficult for doctors to accurately determine your baby's weight.

However, this method is still used to detect abnormalities in the child's weight, allowing the doctor to conduct more in-depth examination.

Why must estimate the weight of the fetus?

One of the reasons you need to see a doctor during pregnancy is to monitor your baby's development, especially during the last few months of pregnancy.

In the past, the weight of the fetus was estimated by subtracting the weight of the current mother from the weight before pregnancy. However, this method is very misleading because it forgets to subtract other factors such as the weight of amniotic fluid, placenta or even the mother's weight gain during pregnancy. Later, people used ultrasound as a method to estimate fetal weight. Although this method has errors, but this method is more accurate than the previous methods.

In the event that your baby's estimated weight is significantly greater than the standard fetal weight at that gestational age, some doctors may prescribe a cesarean section. In general, doctors will prescribe cesarean section when a fetus has an estimated weight of more than 4.5kg, often in the case of an enlarged fetal's organs (macrosomia syndrome) caused by a pregnant mother. gestational diabetes.

The first danger of having a baby with too much weight is often born with a shoulder dystocia. This happens when a baby's body becomes trapped in the mother's womb and can damage certain nerves in the baby's arms and shoulders. This can cause permanent damage to the child's arm muscles, while also damaging the mother's pelvic region.

The doctor may prescribe a cesarean section if the baby's weight is too great. However, sometimes the expected weight can be higher than your baby's actual weight at birth. That is why you should not use this estimation method to make decisions about your form of birth.

Ultrasound in the 3rd trimester of pregnancy

During the last trimester of pregnancy, especially the pre-labor period, you will be asked to periodically have regular ultrasounds. Some of the things that doctors want to consider through an ultrasound result:

Baby's position

Placenta position

Amniotic volume

Biophysical examination: is performed to examine the state of fetal movement, respiratory movement and muscle tone.

Even if your baby is larger than normal, you can still give birth without a cesarean section. Predictive weight is only one factor that helps doctors consider choosing the most suitable method of birth and avoiding risks for both mother and baby.

Ultrasound is not an accurate method for determining the baby's size and weight, but it is still widely used because of its convenience and ease of implementation. The implementation of an ultrasound method helps doctors estimate and give more in-depth exploration methods when seeing abnormalities in baby's weight. aFamilyToday Health hopes pregnant mothers can find an answer to the question: "Fetal weight ultrasound is correct?".