At 8 weeks of pregnancy, your baby is about the size of a raspberry, measuring roughly half an inch from head to rump. It has a recognizably human shape, with a large head, tiny forming limbs, and the beginnings of facial features. This week marks a major milestone: the transition from embryo to fetus, meaning all major organ systems are now in place and will spend the rest of pregnancy growing and maturing.
Overall Size and Shape
The crown-to-rump length at 8 weeks is typically 14 to 20 millimeters, or just over half an inch. The head makes up nearly half of that total length, giving the baby a top-heavy appearance. The body has straightened out compared to earlier weeks, when it was tightly curled in a C-shape. A small embryonic tail that was visible in earlier weeks has now almost completely disappeared, absorbed back into the body by the end of this stage.
Despite being so tiny, the proportions are shifting toward something more human-looking each day. The torso is elongating, and the limbs are extending outward rather than pressed flat against the body.
Face and Head
The face is taking shape quickly during week 8, though it still looks very different from a newborn’s. The tip of the nose is forming, and the upper lip is visible. Two dark spots mark where the eyes are developing beneath paper-thin skin. The eyelids are in the process of fusing shut. At the start of week 8, a gap still exists between the upper and lower eyelid folds, and the developing cornea is visible through it. By the end of the week, the eyelids have completely fused together, and they won’t reopen until around week 26 of pregnancy.
Small folds on the sides of the head mark where the outer ears are forming, though they sit lower than their final position. The inner ear structures responsible for balance are also developing.
Arms, Legs, Fingers, and Toes
The arms and legs are clearly visible at 8 weeks, though they’re still very short. Elbows and wrists have formed, and the arms can bend. The fingers and toes exist but are still webbed, connected by thin tissue that gives the hands and feet a paddle-like look. That webbing breaks down over the coming days, and by the end of week 10, the digits will be fully separated and noticeably longer.
The baby can make small, spontaneous movements at this stage, though you won’t feel them for several more weeks. The muscles and nerves are just beginning to coordinate.
Skin and Outer Appearance
The skin at 8 weeks is extremely thin and almost completely transparent. Blood vessels are visible through it, giving the embryo a reddish appearance. There’s no fat beneath the skin yet, so the developing structures underneath, including the spine and forming organs, can be seen through the surface. Layers of skin cells are present but won’t thicken or become opaque for weeks.
Heart and Internal Organs
The heart has been beating since around week 5 or 6, and by week 8, it’s pumping at a rapid pace. A healthy heart rate at this stage is above 110 beats per minute, and most embryos clock in between 150 and 170. For comparison, a resting adult heart beats 60 to 100 times per minute. The heart has divided into four chambers, though it’s still tiny, roughly the size of a poppy seed.
All major organ systems are now present in at least a basic form. The liver, kidneys, and lungs are developing, along with the intestines, which are so long relative to the baby’s body that a portion of them temporarily extends into the umbilical cord. The brain is growing rapidly, producing roughly 100 new nerve cells every minute. By the end of this week, the organ groundwork is complete, which is why medical terminology shifts from “embryo” to “fetus” at the start of week 9.
What You See on an 8-Week Ultrasound
If you have an ultrasound at 8 weeks, you’ll see a few key structures. The gestational sac appears as a dark circle on the screen. Inside it, you’ll spot the yolk sac, a small round structure that provides nourishment before the placenta takes over. The baby itself shows up as a small, bright shape within the sac, often called the fetal pole at this early stage.
At 8 weeks, the baby is large enough to be clearly visible when the gestational sac measures over 20 millimeters. You should be able to see a flickering motion on the screen, which is the heartbeat. Most providers will measure the crown-to-rump length to confirm gestational age. The image won’t look much like a baby to an untrained eye. It often resembles a small gummy bear: a large round head, a curved body, and tiny limb buds. Detailed features like individual fingers or facial structures aren’t visible on a standard ultrasound at this stage.
How 8 Weeks Compares to Nearby Weeks
Development moves fast in the first trimester, so even a week makes a noticeable difference. At 7 weeks, the embryo still has visible webbing on the hands, the tail hasn’t fully receded, and the face is much less defined. By 9 weeks, the baby officially enters the fetal period, the fingers and toes are separating, and the body proportions start looking slightly less head-heavy. At 8 weeks, you’re right at the transition point: all the basic structures are built, and the next 32 weeks are about growing them to full size.