Fetal Growth Scan
As the delivery date nears and the pregnancy progresses towards the last trimester, you may be excited and anxious to know how your soon-to-be-born little one is doing inside the womb. Your baby is also changing rapidly and getting ready for birth. The doctor may advice a fetal growth scan at this point that will give the parents and their healthcare providers a glimpse into how the baby is growing.
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What is a Growth Scan?
A growth scan in pregnancy, also called the third trimester scan, is done in the last trimester to check the development and well-being of the baby. The ultrasound scan that produces a 2-D, black and white image of the baby is also done to determine the amount of amniotic fluid in the womb and position of the placenta. It can be done once or many times (as per the requirement). The first foetal growth scan is suggested between 28 weeks and 32 weeks of pregnancy to determine the foetal wellbeing.
The second growth scan and colour Doppler studies are done closer to the due date, between 36 and 40 weeks.
Growth Scan Measurements: Understanding BPD, HC, AC, FL and EFW
A growth scan uses several fetal measurements to assess how the baby is growing. Doctors interpret these measurements together rather than relying on one number.
| Measurement | Full Form | What It Measures |
|---|---|---|
| BPD | Biparietal diameter | Width of the baby’s head |
| HC | Head circumference | Circumference of the baby’s head |
| AC | Abdominal circumference | Circumference of the baby’s abdomen |
| FL | Femur length | Length of the baby’s thigh bone |
| EFW | Estimated fetal weight | An ultrasound-based estimate calculated from selected fetal measurements |
The ultrasound machine compares these measurements with reference ranges for the baby’s gestational age. Your doctor also looks at how the measurements relate to one another and, when previous scans are available, how the baby has grown between scans.
A measurement above or below an average value does not by itself confirm a problem. Family characteristics, pregnancy dating, fetal position and normal biological variation can all influence measurements.
For a detailed explanation of the abbreviations that appear on pregnancy ultrasound reports, see Fetal Biometry in Pregnancy: Understanding BPD, HC, AC and FL Measurements.
When is the growth scan done?
The growth scan is done in the last trimester of pregnancy, anytime between 28 and 40 weeks of gestation. Your doctor may offer two scans —
First one is at around 28–32 weeks to ensure the normal growth of the baby.
The second one may be done closer to the due date along with colour Doppler studies, between 36–40 weeks to examine the baby’s position and decide on the type of delivery.
Why get a Growth Scan?
A Growth Scan is important to confirm the normal development of the foetus inside the womb.
To make it simpler, a growth scan is used to:
- Check if the baby is healthy by monitoring the baby’s movement, breathing, and stretching.
- Learn the position and weight of the baby.
- Determine the amount of amniotic fluid present.
- Check the position and maturity of the placenta.
- Check the position of the umbilical cord.
- Check the circulation .
- Learn how a previous caesarean scar looks.
- Monitor a twin pregnancy.
How is growth scan done?
A sonographer asks the patient to lie on a couch, uncovers the abdomen and applies gel on it. Then he/she passes a handheld probe over the skin of the abdomen to examine the baby’s body. The gel is applied to make sure that there is good contact between the probe and the skin. As the probe moves, a black and white 2-D image of the baby will appear on the ultrasound screen.
With the help of the image on the screen, the doctor checks how the baby is doing by checking movement, breathing, etc, and rates the development on a total score of 10 (modified Mannings score). A high number indicates that the baby is doing well whereas a lower score may suggest that the baby is not getting enough oxygen from the placenta.
The doctor also checks the circumference of the baby’s head (HC) and abdomen (AC) to check if the baby is growing well inside the womb. The scan also identifies gestational diabetes. If the amniotic fluid is more than it should be, it is a sign that the mother may have gestational diabetes.
To find out more about how the baby is doing, the sonographer may perform a Doppler scan to see how well the placenta is functioning. This is done by measuring the flow of blood between the placenta and the baby.
What May a Growth Scan Check at Different Weeks of Pregnancy?
Doctors choose the timing of a growth scan according to the reason for monitoring the pregnancy. One woman may need a single scan, while another may need more than one to compare growth over time.
| Pregnancy Stage | What the Scan May Help Assess |
|---|---|
| Around 28 weeks | Fetal measurements, estimated weight, amniotic fluid and early third-trimester growth pattern |
| Around 30 weeks | Interval growth, fetal size and whether measurements remain appropriate for gestational age |
| Around 32 weeks | Continued fetal growth, estimated weight, amniotic fluid, placenta and fetal position |
| 35–36 weeks or later | Growth closer to term, fetal position, fluid levels and other findings when clinically required |
Doctors may schedule scans at different weeks when maternal conditions, fetal growth concerns or previous ultrasound findings require closer observation.
The important factor is not simply the week of the scan. Comparing measurements over an appropriate interval can show whether the baby continues to grow along an expected pattern.
Growth Scan in Pregnancy: Step-by-Step
A growth scan in pregnancy is a part of a routine prenatal checkup that assesses a baby’s growth and development. It involves the following steps:
1. Scan Preparation
Before the scan, the doctor would advise the expecting mother to drink lots of water. This is done to fill the bladder as it helps in improving the quality of scan images.
2. Arrival
Upon arriving at the clinic, the mother would be asked to lie down on the examination table after changing into a gown.
3. Application of Gel
After changing into a gown, a water-based gel would be applied to the abdomen. This gel helps in transmitting sound waves and facilitates the scanning process.
4. Ultrasound Probe
Once a gel is applied, the doctor would use an ultrasound probe to capture real-time images of the foetus. The probe works by sending sound waves into the body that are bounced from the foetal tissues to create a real-time image on the screen.
5. Scanning Procedure
The ultrasound probe would be moved at different angles on the abdomen to create different images of the foetus. The resulting images would measure the circumference of the baby’s head and abdomen and femur length to determine the baby’s weight.
6. Evaluation
During this step, the captured images would be analyzed to assess the position of the baby in the womb, the amount of amniotic fluid, and the position of the placenta.
7. Discussion
Once the scan is done and the doctor has evaluated the results, these would be discussed with soon-to-be parents. If needed, further testing or scans would also be carried out to ensure the baby’s correct development and mitigate risks (if any).
What does the growth scan report show?
The growth scan report during pregnancy is an important tool to find out how well your little one is developing in the womb and to reassure parents about the baby’s well-being.
What the scan reveals—
Movement, breathing and stretching of the baby is as desired.
Baby’s size and weight: If the baby is too big, it could be an indication that the mother has gestational diabetes. If the baby is too small it could be because of less oxygen flow or lack of nutrients through the placenta to the baby. Your doctor will also measure head circumference, abdomen and bones to arrive at the baby’s weight.
Blood and nutrient flow: The growth scan checks for normal blood flow to the umbilical cord and placenta which will ensure oxygen and nutrients supply to the baby is in the normal ranges.
The volume of amniotic fluid is enough for the baby to be comfortable inside the womb.
Position of the placenta: It should not be too high or too low.
Position of the foetus: This is important to determine the type of delivery. The baby should be in a head-down position for normal delivery. The scan will check if the baby is in a breech (head up position). Then your Gynaecologist may suggest a rotation manoeuvre or Caesarean section delivery.
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Duration of Growth Scan
In general, a growth scan is a short procedure that approximately takes 20-30 minutes. It may, however, take longer in case of issues or if additional testing is required.
The procedure may not continue for 20-30 minutes and the doctor may halt in between to gather certain measurements or to gain insights into the overall baby’s development. Hence, the duration may vary depending on the case.
Interpreting the Results of a Growth Scan in Pregnancy
The results of a growth scan play a pivotal role in determining the growth, development, and overall health of the foetus during pregnancy.
Below are the key parameters that help doctors in interpreting the results:
1. Normal Ranges
The first thing a doctor would do is compare the produced measurements during the growth scan to established norms for foetal development. This will include the gestational age of the baby, the medical history of the expecting mother, and other key factors.
2. Abnormal Results
If the growth scan results show any abnormality, additional testing or monitoring would be required. In such cases, the doctor will discuss the results and implications of abnormalities with the expecting mother and explain the further steps.
3. False Positives
Although growth scans are accurate these can sometimes provide inaccurate results called false positives. In such cases, the baby may appear either smaller or larger than its actual size. This, however, does not indicate a problem with pregnancy and an additional scan would be conducted to confirm the results.
4. Follow Up
Although the growth scan during pregnancy would give an idea of what is happening inside the womb, it is still advised to keep visiting the doctor for all scheduled prenatal appointments and follow all the suggested recommendations.
What Do Growth Percentiles and Estimated Fetal Weight Mean?
A growth scan may report an estimated fetal weight (EFW) and show where individual measurements or the estimated weight fall on a growth chart.
A percentile compares the baby’s measurement with reference data for babies at a similar gestational age. It does not work like an examination score, and a higher percentile does not automatically mean that the baby is healthier.
Doctors look at:
- the baby’s estimated fetal weight
- abdominal circumference
- head and femur measurements
- change in growth between scans
- amniotic fluid
- Doppler findings when required
- maternal and pregnancy factors
The pattern matters more than one isolated number. A naturally smaller baby may continue to grow consistently, while a change in growth pattern may prompt additional monitoring.
What If the Baby Measures Smaller Than Expected?
If a growth scan shows that the baby measures smaller than expected, your doctor will assess whether the baby is naturally small or whether fetal growth may require closer monitoring.
The next step may include:
- another growth scan after an appropriate interval
- assessment of amniotic fluid
- Doppler ultrasound
- review of maternal blood pressure and health
- closer fetal monitoring when clinically indicated
Doctors use the term fetal growth restriction (FGR) when a baby does not appear to be reaching its expected growth potential. A single small measurement does not confirm FGR.
For a fuller explanation of how doctors distinguish a small baby from growth restriction, link naturally to Fetal Growth Restriction (IUGR): Causes, Diagnosis and Pregnancy Monitoring.
Why Do Doctors Recommend You To Get a Growth Scan In Pregnancy Done?
A growth scan is a crucial part of prenatal checkups that confirm the normal development of the foetus inside the womb. The doctors usually recommend a growth scan to:
1. Check the overall health of the baby including its movement, breathing, and stretching.
2. Determine the weight and position of the baby.
3. Evaluate the amount of amniotic fluid in the womb.
4. Check the maturity and position of the placenta.
5. Assess the position of the umbilical cord.
6. Monitor blood circulation in the baby’s body.
7. Monitor the growth and development of twins (if present).
8. Examine the appearance of a previous caesarean scar (if present).
What Does a Fetal Growth Scan Involve?
A fetal growth scan is not as intimidating as it sounds. It is a straightforward process that provides a detailed account of the baby inside the womb.
The process starts right from having water to fill the bladder. Adequate water is required in the bladder to undertake the scan. Following this, a slippery gel is applied to the abdomen and an ultrasound probe is moved to the tummy area. This gel facilitates the ultrasound beams to enter the abdomen as well as allows the probe to move easily on the area. The entire process takes approximately 20-30 minutes.
In addition to this, the doctor may also conduct a transvaginal scan to have a better glimpse at the lower edge of the placenta and cervix. Unlike the growth scan, this scan requires an empty bladder. The scan is performed to measure the length of the cervix and analyze the body’s preparation for delivery.
When Is a Growth Scan Combined With Doppler?
A doctor may recommend a growth scan with Doppler when the pregnancy needs additional information about blood flow between the mother, placenta and baby.
The growth scan measures fetal size and growth, while Doppler ultrasound examines blood-flow patterns in selected vessels.
Doctors may consider Doppler assessment when:
- the baby measures smaller than expected
- fetal growth slows between scans
- placental function requires closer assessment
- the mother has high blood pressure or pre-eclampsia
- another pregnancy factor requires additional monitoring
A Doppler scan does not replace fetal growth measurements. Doctors interpret both assessments together when they need a more complete picture of fetal wellbeing.
Add a contextual link here to Doppler Scan in Pregnancy: Why It Is Done and What It Measures.
Price/Cost of Growth Scan In Pregnancy
The cost of a foetal growth scan during preganancy varies depending on the patient’s history, location, and facility. An ultrasound fetal growth scan price at Motherhood Hospital ranges from Rs.2000/- to Rs.5000/– (Varies unit to unit).
Final Thoughts
A fetal growth scan is a crucial part of the prenatal checkup routine that monitors the overall health and development of the growing foetus. This essential scan is recommended by doctors from the third trimester until delivery to monitor the baby. This ensures that your baby is healthy and mitigates any potential issues (if any).
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Our team of doctors do their best to ensure the good health of mother and child. They provide assistance with all tests/procedures.
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What Does Amniotic Fluid Tell Doctors During a Growth Scan?
A growth scan also assesses the amount of amniotic fluid around the baby. Doctors may record the amniotic fluid index (AFI) or use another ultrasound method to estimate fluid volume.
Fluid levels provide additional information about the pregnancy, but doctors do not interpret them alone. They consider fetal growth, placental function, gestational age and other scan findings.
When fluid appears lower or higher than expected, your doctor may recommend follow-up based on the complete clinical picture.
For more detail, link Amniotic Fluid Index (AFI) in Pregnancy: Normal Levels and Why They Matter.
Frequently Asked Questions About Growth Scans
Doctors often perform growth scans during the third trimester, but there is no single week that suits every pregnancy. The timing depends on why your doctor wants to assess growth. Scans may take place around 28, 30 or 32 weeks, or later when continued monitoring is necessary.
A growth scan commonly measures the baby’s head, abdomen and femur. These measurements may appear as BPD, HC, AC and FL on the report. Ultrasound software can use selected measurements to calculate an estimated fetal weight.
Yes. Doctors commonly assess fetal growth during this period when clinically indicated. The exact timing depends on the pregnancy. A scan at 30 or 32 weeks can assess fetal measurements, estimated weight, amniotic fluid and other findings relevant to fetal wellbeing.
No. Ultrasound calculates an estimated fetal weight from fetal measurements. It cannot determine the baby’s exact weight before birth. Doctors use the estimate mainly to assess growth patterns and identify babies who may need additional monitoring.
No. A growth scan primarily measures fetal size and assesses growth. Doppler ultrasound assesses blood-flow patterns in selected maternal, placental or fetal vessels. Doctors may perform both together when they need additional information about placental function or fetal wellbeing.
Yes. An anomaly scan primarily examines the baby’s anatomy during the second trimester. A growth scan later in pregnancy focuses more closely on fetal size, growth progression, estimated weight, fluid and other indicators of wellbeing. Both scans may include fetal measurements, but they answer different clinical questions.
