At 8 weeks pregnant, your baby is about the size of a raspberry, measuring roughly 14 to 15 millimeters from crown to rump (just over half an inch) and weighing around 1 gram. Despite being tiny enough to sit on the tip of your finger, the embryo already has a recognizably human shape, with a head, body, and tiny limb buds that are rapidly taking form.
Overall Size and Shape
Eight weeks marks the final stretch of the embryonic period. After this point, the developing baby officially transitions from “embryo” to “fetus,” a milestone set by the American College of Obstetricians and Gynecologists at 9 weeks after fertilization. At this stage, the head is still disproportionately large compared to the rest of the body, making up nearly half of the embryo’s total length. The body has straightened out from its earlier C-shaped curl, and one of the most visible changes is that the small tail-like structure present in earlier weeks has disappeared. Most humans grow this tail in the womb, and it’s typically gone by week 8.
Hands, Feet, and Limbs
The arms and legs are growing quickly but are still very short, more like small paddles extending from the body. The most dramatic change happening right now involves the fingers and toes. At 8 weeks, the hands and feet still look webbed, with thin tissue connecting the digits. By 7.5 weeks, the fingers begin to separate, and by the end of week 8, distinct fingers and toes emerge as the webbing between them breaks down. The arms are long enough that the hands can meet in front of the body, though they’re still incredibly small.
Facial Features
The face is starting to look more human, though it’s far from fully formed. The eyes are visible as dark spots on the sides of the head, still set wide apart and covered by skin that will eventually become eyelids. The tip of the nose is taking shape, and the upper lip has formed. Small folds on either side of the head mark where the outer ears are developing, though they sit lower than they will later in pregnancy. The mouth and jaw are present, and the basic structures inside, like the tongue, are beginning to form.
Early Brain Activity and Movement
Between 8 and 10 weeks, the embryo begins its first movements, flexing its tiny arms, legs, fingers, and toes. These movements eventually grow more complex, progressing into stretching, yawning, hiccupping, and swallowing. At 8 weeks specifically, these motions are just beginning and are far too small and subtle for you to feel. You won’t notice any movement until somewhere around 16 to 22 weeks, but the neural groundwork is being laid right now. The brain is growing rapidly, developing the connections that drive this early motor activity.
Major Organs Taking Shape
This is a critical period for organ development. All of the major organ systems are actively forming. The heart has been beating for a couple of weeks already, and by now it has divided into four chambers and is pumping blood at a rapid rate. The lungs, liver, kidneys, and digestive tract are all present in rudimentary form. None of these organs are fully functional yet, but the basic architecture is in place. This is one reason the first trimester is considered such a sensitive window: the building blocks for every major system are being assembled simultaneously.
What You’ll See on an Ultrasound
If you have an ultrasound around 8 weeks, you’ll see more than you might expect, but less than you might hope for. The gestational sac is clearly visible, and inside it you can see the yolk sac (a small bubble-like structure that provides nutrients before the placenta fully takes over) alongside the embryo itself. The embryo appears as a small, bright shape with a flickering spot where the heartbeat is. On a standard 2D ultrasound, you can usually make out the head and body, and sometimes the tiny limb buds, but fine details like fingers or facial features aren’t visible at this size. The image often looks more like a small bean or gummy bear than what most people picture when they think of a baby.
Your provider will likely measure the crown-rump length to confirm your due date, since this measurement is one of the most accurate ways to estimate gestational age in early pregnancy. A typical reading at 8 weeks falls around 14 to 15 millimeters.