Pregnancy takes you on a journey full of anticipation, care, and regular check-ins with your doctor to ensure everything progresses well. Growth scans play a key role among these check-ins. If you’ve heard your doctor mention them—or wonder why you might need more than one ultrasound in the third trimester—this blog will help.
What Is a Growth Scan?
A growth scan uses ultrasound during the second half of pregnancy to assess how well your baby grows. It tracks the baby’s development, evaluates the placenta, and checks the amniotic fluid and blood supply.
What Does a Growth Scan Check?
- Fetal Growth:
The sonologist measures the baby’s head, abdomen, and femur to estimate fetal weight and growth percentile. These measurements help identify whether the baby grows too slowly (fetal growth restriction) or too quickly (macrosomia).
- Amniotic Fluid Volume:
The scan measures the fluid around the baby to reflect placental health and indicate the baby’s environment in the womb.
- Doppler Blood Flow Studies:
These assess how well blood flows through the umbilical cord and other key vessels. Abnormal flow can suggest placental issues or fetal distress.
When Do Doctors Perform Growth Scans?
Doctors usually perform growth scans in the third trimester at these key time points:
- Around 28 weeks: This scan helps establish a baseline growth trajectory, especially in high-risk pregnancies or when earlier scans raise concerns.
- Around 32 weeks: This checkpoint evaluates ongoing growth, amniotic fluid levels, and placental function.
- Around 36 weeks: The final scan before delivery helps in labor planning, particularly if the baby seems too small, too large, or if any concerns arise regarding the placenta or blood flow.
Doctors may adjust the number and timing of these scans based on your specific pregnancy.
How Do Doctors Perform a Growth Scan?
Doctors typically perform growth scans through the abdominal route.
Here’s what happens:
- You lie down comfortably.
- The sonologist applies gel to your abdomen to help the ultrasound probe capture clear images.
- The sonologist moves the probe over your belly to visualize the baby, take measurements, check the fluid, and assess blood flow.
What If the Doctor Needs to Check Cervical Length?
If your doctor wants to assess cervical length—especially due to concerns about preterm labor, a history of previous preterm birth, or specific symptoms—they may recommend a transvaginal ultrasound.
This scan:
- Uses a thin, covered probe inserted gently into the vagina
- Provides a more accurate cervical measurement than the abdominal scan
- Remains safe and usually painless, though it may cause mild discomfort
So, while most scans occur over the belly, the sonologist may perform a quick internal scan to complete the assessment when needed.
Why Do Doctors Sometimes Include a Structural Survey in a Growth Scan?
Sometimes, the sonologist may spend extra time during the growth scan to re-evaluate the baby’s anatomy—especially if the anomaly scan happened early or if certain structures weren’t clearly visible at that time.
Why Does This Matter?
While the anomaly scan between 18–22 weeks usually detects major structural issues, some abnormalities evolve or become visible only later.
A structural survey during a growth scan allows the sonologist to:
- Reassess organs like the heart, kidneys, and brain
- Detect late-onset or progressive anomalies
- Confirm or follow up on earlier findings
But It Takes Time…
A structural review extends the scan duration. Although not always necessary for everyone, it offers added reassurance. Think of it as a bonus round to check your baby’s well-being.
What If the Doctor Advises a Fluid and Doppler-Only Scan?
Sometimes, your doctor may request a scan that checks only the amniotic fluid level and Doppler blood flow without rechecking the baby’s measurements or anatomy.
Why Does This Happen?
Doctors usually suggest this focused or limited scan in situations like:
- A recent full growth scan
- Ongoing monitoring for growth concerns
- Close to the due date and need for frequent placental monitoring
- Need to avoid repetitive measurements that may confuse growth tracking
In such cases, doctors prefer a shorter scan to gather the specific information they need.
Final Thoughts
Growth scans offer more than numbers and charts—they give a glimpse into your baby’s world. Each scan allows doctors to ensure your baby thrives in the womb. Every scan asks, “Are you okay in there, little one?”
If you have a scheduled growth scan, view it as a valuable chance to learn about your baby’s health. Whether it’s a full scan or a quick fluid and flow check, each one focuses on keeping you and your baby safe and informed.
