.webp)
Fetal biometry refers to the measurements your pregnancy care provider takes during an ultrasound to determine how a fetus is developing. Irregular results usually indicate that more testing is required.
Fetal biometry is an ultrasound-based test used to determine the size of a fetus during pregnancy. It includes of many measurements that inform your pregnancy care provider about how the fetus is developing for its gestational age and whether there are any symptoms of growth concerns. It aids in diagnosing fetal development abnormalities. These illnesses can cause pregnancy difficulties later on.
Prenatal ultrasounds include fetal biometry. It helps assess whether the fetus's size corresponds to its predicted gestational age. The estimated gestational age is a measure of how far along a pregnancy is in weeks.
If the fetus appears to be smaller or larger than its gestational age, your provider may need to conduct additional testing to determine why. This could be caused by the birth parent's underlying health condition, placental difficulties, or a congenital defect in the fetus.
Keep in mind that just because prenatal biometry data show whether a fetus is ahead or behind its age does not necessarily indicate that something is wrong. It is quite typical to have erratic outcomes.
Fetal biometry is a test that estimates the size of a fetus during pregnancy. By measuring certain body components, your physician can create an overall picture of the fetus's size and compare it to what is deemed normal for its age.
The parameters this test measures include the following:
BPD (biparietal diameter): The diameter of the head.
HC (head circumference): The length going around the head.
AC (abdominal circumference): The length going around the belly.
FL (femur length): The length of the femur bone.
CRL (crown-rump length): The length from the top of the head to the bottom. This measurement is more accurate in the first trimester. After 12 weeks of pregnancy, the parameters above are better at giving an overall assessment of growth.
Fetal biometry is a medical word that refers to the measurements taken during a standard prenatal ultrasound. Along with evaluating the amount of amniotic fluid and blood flow through the umbilical cord, an ultrasound technician utilizes their gear to take measurements to determine if the fetus is the appropriate size for its age. During a prenatal ultrasound, a transducer is moved around your abdomen. If you're fewer than 12 weeks pregnant, they may perform a transvaginal ultrasound.
If you're looking at an ultrasound monitor, you might notice your technician clicking and dragging lines across the screen. This is how they measure the fetus and other elements of the uterus.
Fetal biometry is quite accurate in the early stages of pregnancy. It is one of the most reliable techniques for a healthcare provider to assess a fetus's growth. These measurements are routinely taken during routine ultrasounds in the first and second trimesters. If you have a pregnancy issue or are expecting multiples, your doctor will take these measurements more frequently during your pregnancy. Fetal biometry becomes less precise during the second trimester.
Typical ranges for prenatal biometry vary, and several factors influence what is considered "normal." Each metric has an average measurement across various gestational ages. Furthermore, each pregnancy is unique, and your clinician will take additional aspects into account when evaluating your outcomes.
In centimeters (cm), the median (average) ranges for fetal biometry measurements at roughly 20 weeks gestation are:
Head circumference (HC): 17.5cm.
Abdominal circumference (AC): 14.9cm.
Biparietal diameter (BPD): 4.9cm.
Femur length (FL): 3.2cm.
Because the likelihood of having a result that is exactly the median is low, you will also receive percentile values. A percentile is a tool to compare persons who have comparable qualities. In this example, healthcare providers employ percentiles to represent the typical growth range of fetuses with the same gestational age.
For example, your results may indicate that the fetus's abdominal circumference is in the 75th percentile. While greater than usual, it is not necessarily cause for concern. Most healthcare providers are unconcerned until a fetus measures below the 10th percentile or above the 90th percentile.
Because each test result is unique, it's always advisable to discuss your results with your physician and what they signify for you. And,
If the results of your ultrasound are irregular, your pregnancy care provider will prescribe more ultrasounds. This allows them to monitor the fetus's growth over time and observe if anything changes. Looking at trends in your data or how they change over time is the most effective technique to confirm fetal biometry. They may also examine the results of your blood work or urinalysis (a test that takes a sample of your urine) to see if they provide any light on why the fetus's measurements were unusual.
A smaller-than-average fetus may signal fetal growth restriction (FGR) or placental issues. A fetus that is larger than typical may indicate that the birth mom has gestational diabetes.
Try not to worry. It is normal for a fetus to measure little or large. In most situations, the fetus is born healthily, with a normal size and weight. Irregular test findings from a single ultrasound are not cause for concern. Your pregnancy care provider will inform you of any additional monitoring and the next steps.
