At 7 weeks pregnant, your baby is about the size of a blueberry, measuring roughly a quarter of an inch from head to rump. It looks like a tiny curved organism with an oversized head at one end and a small tail-like structure at the other. Despite being almost impossibly small, a surprising amount of development is already underway.
Facial Features Are Just Starting
Your baby’s face is in the very earliest stages of forming, and it doesn’t look anything like a face yet. Small depressions where the nostrils will eventually be are just becoming visible on the surface. The beginnings of the retinas (the light-sensing tissue at the back of the eyes) are starting to form, though the eyes themselves are still just dark spots on either side of the head. There’s no defined nose, no lips, and no chin. Think of it as a rough sketch rather than a portrait: the basic layout is being mapped out, but the details won’t fill in for several more weeks.
The Head, Body, and Tail
The most prominent feature at 7 weeks is the head, which is disproportionately large compared to the rest of the body. The brain is growing rapidly, and this growth drives the head’s size. The body curves forward in a C-shape, which is why the measurement used at this stage is called “crown-to-rump length” rather than head-to-toe.
One detail that surprises many parents: your baby still has a small tail. All human embryos develop a relatively long tail early on, which gradually shrinks and disappears by the end of the embryonic phase (around weeks 8 to 9). At 7 weeks, it’s still present but already getting shorter.
Arms and Legs Look Like Paddles
By 7 weeks, limb buds have been growing for about a week, and the ends are starting to flatten out into paddle shapes. These paddles will become the hands and feet. You can’t see individual fingers or toes yet. Instead, the tissue is solid, and the separations between digits will form later as cells between them are naturally broken down. Slight constrictions are beginning to appear where the wrists, ankles, elbows, and knees will eventually bend.
A Beating Heart
One of the most significant milestones at 7 weeks is cardiac activity. The heart structures aren’t fully formed yet, but a heartbeat is typically detectable. At this stage, a normal heart rate is at least 120 beats per minute. For context, that’s roughly twice the resting heart rate of most adults. Below 120 bpm at 6.3 to 7 weeks is considered below the normal threshold and may prompt additional monitoring.
Organs Are Already Forming
Even though your baby is smaller than a fingernail, internal organs are actively developing. The liver is undergoing rapid cell growth, and early bile duct connections between the liver and the gut are being established. The pancreas is beginning to secrete tiny amounts of hormones. The digestive tract is taking shape as a continuous tube, with different segments already assigned to become the stomach, intestines, and other structures. None of these organs are functional in the way they will be at birth, but the foundation is being laid now during a critical window called organogenesis.
What You’ll See on an Ultrasound
If you have an ultrasound at 7 weeks, it will almost certainly be transvaginal rather than abdominal. At this early stage, a transvaginal probe gets close enough to the uterus to produce a usable image, while an abdominal ultrasound often can’t pick up enough detail. Even with transvaginal imaging, don’t expect to see anything that looks like a baby. What you’ll typically see is:
- The gestational sac: a dark, fluid-filled circle that surrounds the embryo
- The yolk sac: a small round structure that provides early nutrition
- The embryo: a small, bright shape inside the sac, often described as looking like a grain of rice
- Cardiac activity: a flickering motion within the embryo, representing the heartbeat
Your provider will measure the embryo’s crown-to-rump length and the size of the gestational sac to confirm how far along the pregnancy is. These measurements are more accurate for dating a pregnancy than counting from your last period, especially if your cycles are irregular.
How Week 7 Fits Into the Bigger Picture
Week 7 falls in the middle of the embryonic period, which runs from roughly weeks 3 through 8. This is the most intensive stretch of structural development in the entire pregnancy. By the end of week 8, nearly every major organ system will have at least a basic version in place, and the embryo will officially be reclassified as a fetus. Right now, at 7 weeks, your baby is in the thick of that building phase: assembling a face, growing limbs, wiring a brain, and beating a heart, all while being no bigger than a blueberry.