Fetal Growth Scan in the Third Trimester
A fetal growth scan is a detailed ultrasound performed in the later weeks of pregnancy, usually between 28 and 40 weeks. The scan checks how well your baby is growing and helps make sure everything is developing normally as you approach your due date.
Your doctor may recommend this scan for several reasons. It is often suggested if you have high blood pressure, diabetes, or other medical conditions, if your belly measurement seems smaller or larger than expected, if you are carrying twins, or if there were concerns on earlier ultrasounds. Many women also have a routine growth scan around 36 weeks, even with an otherwise straightforward pregnancy.
During the scan, the sonographer takes careful measurements of the baby’s head, abdomen, and thigh bone. These numbers are used to estimate the baby’s weight and to see whether the growth is following a healthy pattern. The amount of amniotic fluid around the baby is also checked, along with the baby’s position and the appearance of the placenta. In some cases, blood flow through the umbilical cord is assessed using Doppler to understand how well the placenta is working.
The scan itself usually takes 15 – 20 minutes. You will lie comfortably on the exam table while the probe is gently moved over your abdomen. It is completely painless, uses only sound waves, and is safe for both you and your baby.
A normal result is reassuring and confirms that your baby is growing well. If the scan shows slower or faster growth, reduced fluid, or changes in blood flow, your doctor will explain the findings clearly and discuss the best plan moving forward, which may include more frequent monitoring or decisions about the timing of delivery.
In short, the third-trimester growth scan is a simple, safe, and valuable way to keep a close eye on your baby’s well-being in the final weeks of pregnancy. It is always your choice, and it is only recommended when it can truly help guide your care.
If you are in the third trimester or have any concerns about your baby’s growth, please feel free to schedule a consultation. We will go through your specific situation together and decide whether a growth scan would be helpful for you.
References
1. Khalil A, Sotiriadis A, D’Antonio F, et al. ISUOG Practice Guidelines: performance of third-trimester obstetric ultrasound scan. Ultrasound Obstet Gynecol. 2024;63(1):131-147. doi:10.1002/uog.27538.
2. Cunningham FG, Leveno KJ, Dashe JS, Hoffman BL, Spong CY, Casey BM. Williams Obstetrics. 26th ed. New York: McGraw-Hill; 2022.
3. American College of Obstetricians and Gynecologists. Fetal growth restriction. ACOG Practice Bulletin No. 227. Obstet Gynecol. 2021;137(2):e1-e20. (Reaffirmed 2024).
Maternal–Fetal Medicine Specialist in Bangkok
Dr. Narisra Srikureja Firer (Dr. Niti)
Dr. Niti is a Bangkok-based OBGYN with subspecialty training in Maternal–Fetal Medicine (MFM). She provides comprehensive care for women across all stages of life, including pregnancy care, deliveries, and general gynecological conditions.
She dedicates her time to private practice at Ruamjairak Hospital and Mission Hospital, and serves as a Maternal–Fetal Medicine Consultant at a large government tertiary care center.
To read Dr. Niti’s full bio, click here.
