At 8 weeks of pregnancy, your baby is roughly the size of a raspberry, measuring about 1.5 to 2.3 centimeters from head to bottom. It has a distinctly human shape starting to emerge, with a large head, a curved body, and tiny limb buds that are just beginning to form arms and legs. This is also the final week your baby is medically classified as an embryo; starting at week 9, the term changes to “fetus.”
Overall Size and Shape
At this stage, your baby looks like a small, curved bean. The head makes up nearly half the total body length because the brain is growing rapidly. All of the major organs and body systems are actively developing, even though most are far from finished. The body has a slight C-shaped curl, with a small tail-like structure from earlier weeks that is now shrinking and will soon disappear entirely.
Facial Features Taking Shape
By 8 weeks, your baby’s face has come a long way in a short time. During weeks 5 through 7, five separate tissue folds grew toward each other and fused together to create the basic architecture of the face. By now, that process has formed the forehead, the sides of the face, the middle and sides of the nose, the groove between the nose and upper lip (called the philtrum), and the upper lip itself. The lower jaw is also in place.
The eyes are visible as dark spots on the sides of the head, still spaced far apart. Eyelids are beginning to form but won’t fully close for several more weeks. Tiny ear folds are developing low on the head, and the tip of the nose is becoming more defined. The mouth opening is present, and the upper lip has taken its basic shape. It doesn’t look like a newborn yet, but the blueprint of your baby’s face is clearly there.
Arms, Legs, Fingers, and Toes
Limb development moves quickly during week 8. Early in the week, arm and leg buds are still small bumps on the body. By the end of the week, the upper limbs are noticeably longer and bent at the elbow, and the wrists are forming. The legs are slightly behind the arms in development but are catching up fast.
Hands and feet are present but still paddle-shaped and webbed. The fingers and toes are beginning to lengthen and separate, though they won’t be fully distinct individual digits until the following week or two. Hands and feet are turned slightly inward at this point, which is completely normal.
The Brain and Nervous System
Your baby’s brain is one of the most active areas of growth right now. The neural tube, which first formed around week 5, has developed into the early structures of the brain and spinal cord. Nerve cells are multiplying and beginning to branch out, forming the very first connections that will eventually become the nervous system. The brain is already divided into distinct sections, though it will continue developing well beyond birth.
These early nerve connections are why your baby will start making spontaneous movements around week 12. At 8 weeks, the muscles and nerves aren’t coordinated enough for movement yet, and you won’t feel any kicks for quite a while. Most first-time mothers don’t notice movement until around 20 weeks.
What You’ll See on an Ultrasound
If you have an ultrasound at 8 weeks, the reality on screen looks quite different from the detailed developmental picture described above. Most of those tiny features are too small to see with current imaging. What you will see is a small bean-shaped figure inside a fluid-filled circle called the gestational sac, which is typically 2 to 3 centimeters across. Inside that, you may notice a smaller circle called the yolk sac, which is helping nourish the baby at this stage.
The most dramatic thing on the screen is the heartbeat. A normal heart rate at 8 weeks falls between 150 and 170 beats per minute, roughly twice as fast as yours. You’ll likely see it as a rapid flicker in the center of the embryo. The beginnings of the umbilical cord may also be visible.
At 8 weeks, most providers use a transvaginal ultrasound rather than the kind done on your belly. The transvaginal approach gives a much clearer image because the probe is closer to the uterus. On the screen, you may be able to make out the limb buds as small bumps, but individual fingers and toes won’t be visible yet. The head and body will be distinguishable from each other, and if the technician zooms in, you might catch a glimpse of where the eyes are forming.
Don’t be surprised if the image looks nothing like the illustrations in pregnancy apps. Those illustrations are artistic reconstructions based on developmental science. The ultrasound image is a real-time, grainy snapshot of something barely bigger than a kidney bean, and it’s perfectly normal for it to look abstract.
What’s Happening Inside
Beyond what’s visible, week 8 is a milestone because every major organ system has at least started forming. The heart has been beating since around week 5 or 6 and now has four chambers. The digestive tract, liver, kidneys, and lungs are all in their earliest stages. Bones are beginning to harden from the softer cartilage that formed first, though the skeleton will remain mostly cartilage for months to come.
This is also the week when the gonads begin differentiating based on the baby’s chromosomes, though it’s far too early to detect sex on an ultrasound. That typically becomes possible around 18 to 20 weeks.