At 8 weeks pregnant, the embryo is about the size of a raspberry, roughly half an inch to just over an inch long. It has a recognizably human shape forming, with a large head, tiny limb buds, and the beginnings of facial features, though it still looks quite different from a newborn. This is the final week the developing baby is technically called an “embryo” before graduating to “fetus” at week 9.
Overall Size and Shape
The embryo weighs less than a gram and could sit on the tip of your finger. On an ultrasound at this stage, doctors at UT Southwestern describe the baby as looking like “a tiny teddy bear,” with a disproportionately large head and small limb buds. The head makes up nearly half the total body length because the brain is growing rapidly. A small tail-like structure that was visible in earlier weeks has typically disappeared by week 8.
Facial Features Taking Shape
The face is still very much a work in progress, but the basic architecture is there. The upper lip and nose have formed, though the nose is flat and broad compared to what it will eventually become. Small swellings that will become the outer ears are visible on the sides of the head, outlining the shell-shaped structures you’d recognize later. The eyes are wide-set dark spots on either side of the head, with eyelids just beginning to develop. There’s no chin to speak of yet, and the mouth is a tiny opening, but the jaw and palate are actively forming underneath.
Arms, Legs, and Fingers
By 8 weeks, the limbs have progressed well beyond simple buds. The basic structures of the arms and legs, including the bones and muscle groups, are largely established. Elbows are starting to form, giving the arms a slight bend rather than sticking straight out. The hands and feet exist but still look webbed, with tissue connecting the forming digits. Over the coming days, that connecting tissue will break down through a natural process of cell death, gradually producing separate fingers and toes. The joints won’t be functional for a few more weeks, though. Elbows, knees, and ankles start working around week 11.
What’s Happening Inside
The most dramatic development at 8 weeks is happening where you can’t see it. All of the major organs and body systems are actively developing. The heart has been beating since around week 6, and by week 8 it’s pumping at roughly 150 to 170 beats per minute, which is about twice the rate of an adult heart. This rapid heartbeat is clearly visible on ultrasound and is one of the key things your provider checks at an early pregnancy scan.
The brain is dividing into distinct sections that will eventually control different functions. The liver is proportionally enormous, taking up a large portion of the abdomen because it’s responsible for producing blood cells at this stage. The intestines are growing so quickly that they temporarily extend into the umbilical cord because there isn’t enough room in the tiny abdomen yet. They’ll migrate back inside over the next several weeks.
Movement You Can’t Feel Yet
One of the more surprising things about 8 weeks is that the embryo is already moving. During an ultrasound, you can see the entire baby bouncing around inside the uterus in its sac of amniotic fluid. These spontaneous movements are reflexive, not intentional, driven by the developing nervous system firing signals to brand-new muscles. At roughly an inch long and floating in fluid, though, the embryo is far too small to create any sensation you’d notice. Most people don’t feel fetal movement until at least 14 weeks, and even then it’s subtle enough that you might miss it.
What You’d See on an Ultrasound
If you have an ultrasound around 8 weeks, the image will show a small, curved shape inside a dark circular sac. The head and body are distinguishable but not sharply defined. You’ll likely see a flickering spot in the chest area, which is the heartbeat. Limb buds may be visible depending on the baby’s position and the quality of the equipment. The embryo often appears to be moving or twitching during the scan, which can be reassuring to see even though you feel nothing.
Keep in mind that what you see on the screen is magnified significantly. In reality, the entire embryo is smaller than a kidney bean. The grainy, black-and-white ultrasound image won’t look like the detailed, color-enhanced photographs you might find online, which are typically taken from pregnancies that ended and were studied under special conditions. What you’ll see in the exam room is enough to confirm a heartbeat, estimate size, and help determine your due date.