Fetal Development
Fetal Development Milestones: A Visual Journey
Dr. Honeylet Salavarria
MD, FPOGS, FPSUOG · OB-GYN Ultrasound Subspecialist · 8 min read
Ultrasound lets us watch your baby grow month by month. Here are the key milestones we look for at each stage — and what you might see on the screen.
6 to 8 weeks: A heartbeat appears
The baby is about the size of a lentil to a blueberry. The heart has begun to beat and can be seen flickering on a transvaginal scan. Tiny buds that will become arms and legs are forming.
9 to 13 weeks: From embryo to fetus
By 10 weeks, the baby is officially called a fetus. Fingers, toes and facial features are forming, and the baby may be seen moving and stretching. The major organs are in place and continue to mature.
14 to 20 weeks: Growing and moving
The baby grows quickly. The skeleton hardens, the baby can make sucking movements, and many mothers start feeling the first flutters ("quickening") between 16 and 20 weeks. The baby's sex may be visible on ultrasound from around 16 weeks.
20 to 28 weeks: The detailed anatomy check
This is the ideal time for the Congenital Anomaly Scan (best done at 24 to 28 weeks), where we carefully check the brain, face, spine, heart, kidneys, limbs and more. It is also a lovely time for a 3D/4D scan, when the baby's facial features are clearly visible.
28 to 40 weeks: Getting ready for birth
In the third trimester, the baby gains weight, the lungs mature, and the baby usually turns head-down. Growth scans and biophysical profiles check the baby's size, position, amniotic fluid and well-being, and may include Doppler studies of blood flow.
Each scan is a window into your baby's growth. Following the recommended schedule helps us catch any concerns early and keep you both healthy.
This article is for general education and does not replace advice from your doctor.
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