At 7 weeks pregnant, your baby is roughly the size of a blueberry, measuring about 1 centimeter (just under half an inch) from the top of the head to the bottom of the rump. That measurement, called crown-to-rump length, is how size is tracked this early because the legs are too tiny and curled to factor in. Your baby is still technically an embryo at this stage and won’t be called a fetus until around week 10.
What Your Baby Looks Like Right Now
At 7 weeks, the embryo has a distinctly curved shape with a relatively large head and a small tail-like structure that gives it a tadpole or seahorse appearance. That tail is temporary and will recede over the coming weeks as the lower spine develops. The head looks oversized compared to the rest of the body because the brain is growing rapidly, already beginning to divide into three primary sections that will eventually control thinking, movement, and basic body functions like breathing and heart rate.
Tiny arm and leg buds that started forming around week 6 are now more defined, though they still look like small paddles. Over the next week or two, those paddles will start to develop ridges called digital rays, which are the earliest outlines of fingers and toes. The face is also taking shape in a basic way: dark spots mark where the eyes will be, small pits indicate future nostrils, and the mouth opening is forming. None of these features look recognizably human yet, but the foundational structures are all being laid down at a remarkable pace.
The Heart Is Already Beating
One of the most significant developments by week 7 is the heartbeat. The heart started as a simple tube and has now divided into chambers. It beats at a rapid rate, typically between 100 and 160 beats per minute, which is roughly twice the speed of an adult heart. If you have an ultrasound around this time, the heartbeat is usually the most visible and reassuring sign. In fact, 7 weeks is generally considered the earliest point at which a heartbeat can be reliably detected on a scan.
What You Might See on an Ultrasound
If your provider orders an early ultrasound around 7 weeks, it will almost certainly be a transvaginal scan rather than the abdominal kind you might picture. At this stage, the embryo is so small that an external probe simply can’t pick up enough detail. On the screen, you’ll likely see the gestational sac (a dark circular area), the yolk sac (a smaller bright ring that nourishes the embryo before the placenta takes over), and the fetal pole, which is the early shape of your baby. A flickering motion on the fetal pole is the heartbeat.
Don’t be alarmed if the image doesn’t look like much. At this size, there’s very little to distinguish. Some people see a tiny bean shape, others just see a bright dot. The main purpose of a scan this early is to confirm the pregnancy is in the right location, check for a heartbeat, and estimate how far along you are based on the embryo’s measurements.
Changes in Your Body at 7 Weeks
While your baby is blueberry-sized, your uterus has already grown to about the size of a lemon, roughly double its pre-pregnancy size. You won’t have a visible bump yet since the uterus is still tucked behind your pelvic bone, but you might notice your waistband feels a bit tighter or that bloating makes your lower abdomen feel full.
Pregnancy symptoms tend to be ramping up around this point. Nausea (with or without vomiting), breast tenderness, fatigue, and frequent urination are all common. These are driven by rising hormone levels, particularly progesterone and hCG, which are supporting the pregnancy and helping the placenta develop. The intensity varies enormously from person to person. Some people feel terrible at 7 weeks, others barely notice anything, and both scenarios are normal.
How Size Is Measured This Early
Crown-to-rump length is the standard measurement in the first trimester because the embryo is curled into a C shape, making a head-to-toe measurement impossible. At 7 weeks, that measurement falls between about 8 and 11 millimeters, depending on whether you’re closer to 7+0 or 7+6 days. Growth at this stage is fast. Your baby will roughly double in size over the next two weeks, reaching about 2.3 centimeters (just under an inch) by week 9.
Small differences in measurement at this stage don’t usually indicate a problem. Ultrasound dating can be off by a few days, and embryos grow at slightly different rates. If a scan puts you a few days ahead or behind where you expected, your provider will likely adjust your due date accordingly rather than flag it as a concern.