Sonography, commonly known as an ultrasound scan, is one of the most important diagnostic tools during pregnancy. It uses high-frequency sound waves to create images of the developing baby, the placenta, and the mother’s reproductive organs. Different types of sonography are performed at various stages of pregnancy to monitor the baby’s growth, detect any complications, and ensure a safe delivery.
Let’s look at the main types of sonography in pregnancy and their purposes.
When it’s done: Between 6–10 weeks
Purpose:
• Confirms the due date.
• It can be done by using transvaginal Sonography and abdominal Sonography
• Detects multiple pregnancies (twins or triplets).
• Verifies heartbeat and normal development.
This early scan helps establish how far along the pregnancy is and ensures that the baby is developing inside the uterus.
When it’s done: Between 11–14 weeks
Purpose:
• Measures the fluid-filled space at the back of the baby’s neck.
• Helps detect chromosomal abnormalities like Down syndrome.
The NT scan is often combined with a blood test for a more accurate screening of genetic conditions.
When it’s done: Around 18–22 weeks
Purpose:
• Examines the baby’s organs, brain, spine, heart, limbs, and kidneys.
• Checks for congenital or structural abnormalities.
• Confirms placenta position and amniotic fluid volume.
This detailed scan is one of the most crucial ultrasounds, giving parents a clear picture of the baby’s health.
When it’s done: Between 28–32 weeks
Purpose:
• Measures foetal growth parameters such as weight and head size.
• Checks placental health and blood flow through the umbilical cord.
• Monitors amniotic fluid levels and overall well-being.
It helps ensure the baby is developing normally and that the pregnancy is progressing safely.
When it’s done: Usually in the third trimester
Purpose:
• Assesses blood flow between the placenta and baby.
• Detects issues with foetal oxygen supply or growth restriction.
This scan is particularly important for high-risk pregnancies, such as those involving hypertension, diabetes, or growth-related concerns.
When it’s done: After 32 weeks
Purpose:
• Combines an ultrasound with a non-stress test to check the baby’s movements, breathing, and heart rate.
• Assesses the baby’s overall health before delivery.
BPP is often recommended when doctors need to ensure that the baby is thriving inside the womb.
When it’s done: Anytime after 24 weeks
Purpose:
• 3D scans create lifelike images of the baby’s features.
• 4D scans show real-time movement (like yawning or stretching).
While mainly used for bonding and visualisation, 3D and 4D scans can also help detect certain structural issues in the baby’s face or limbs.
Each type of sonography in pregnancy serves a unique purpose, from confirming conception to assessing foetal growth and preparing for delivery. These scans are safe, painless, and vital for monitoring both maternal and foetal well-being.
Regular ultrasounds, as advised by your obstetrician, provide reassurance and allow early detection of potential issues, ensuring the best care for both mother and baby throughout pregnancy.
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