At 8 weeks pregnant, your baby is about 1.6 centimeters long (roughly half an inch) and weighs around 1 gram. That’s about the size of a raspberry. Despite being tiny enough to sit on your fingertip, your baby is in the middle of a massive stretch of development, with every major organ system taking shape this week.
Size and Weight at 8 Weeks
Doctors measure early pregnancies using “crown-rump length,” which is the distance from the top of the head to the bottom of the torso (legs aren’t included because they’re curled up tight). At 8 weeks, that measurement falls around 15 to 16 millimeters. For context, that’s slightly smaller than a dime’s diameter. Weight is negligible at this point, roughly 1 gram or 0.04 ounces.
Growth is happening fast, though. Just two weeks ago, at week 6, the embryo was barely visible on ultrasound. By week 10, it will have more than doubled in length. This stretch from weeks 6 through 10 is one of the most rapid growth periods of the entire pregnancy.
What’s Developing This Week
Week 8 is a turning point. All of the major organs and body systems are actively forming. The hands and feet exist but still have a webbed appearance, with individual fingers and toes not yet separated. Eyes are becoming visible as dark spots on the sides of the head, and the ears are starting to take shape.
The umbilical cord is now fully developed and working, transporting oxygen and nutrients from you to the embryo. One quirky milestone: the small tail-like structure that all human embryos develop earlier in pregnancy disappears by this week as the body takes on a more recognizably human shape.
Inside the brain, nerve cells are beginning to migrate from where they’re produced to their permanent positions. This migration process starts around weeks 6 to 8 and continues for months, eventually building the layered structure of the brain. The innermost brain layer is already forming by week 8.
Embryo or Fetus?
At 8 weeks, your baby is still technically an embryo. The official switch to “fetus” happens at the end of week 10 of pregnancy (which is 8 weeks after fertilization, since pregnancy is counted from your last menstrual period, not conception). The distinction isn’t just a label. The embryonic period is when all the basic structures are built from scratch. The fetal period, starting at week 10, is when those structures grow, mature, and refine. So right now, your baby is finishing the most foundational building phase of development.
What You’ll See on an Ultrasound
If you have an ultrasound at 8 weeks, it will typically be transvaginal rather than abdominal, since the embryo is still very small. You should be able to see the embryo itself, the yolk sac (a small round structure that provides early nutrition before the placenta fully takes over), and a flickering heartbeat. The yolk sac has been visible since around week 5 and continues growing through week 10. Don’t expect to make out arms or facial features at this stage. On screen, the embryo looks more like a small bean with a pulsing center.
What’s Happening in Your Body
While your baby is raspberry-sized, your uterus has already grown to roughly the size of a tennis ball. That’s about double its non-pregnant size, and it’s starting to press on your bladder, which is why you may find yourself needing the bathroom more often than usual.
Week 8 is often when morning sickness peaks. Not everyone experiences it the same way. Some women feel energized and notice that “pregnancy glow,” while others are exhausted, nauseous, and emotionally up and down. Mood swings are common and driven by the same hormonal shifts fueling all the other changes. Those hormones can also affect your gums, making them more likely to bleed when you brush. Frequent vomiting or cravings for sugary foods can compound dental sensitivity, so this is a good time to pay extra attention to your oral care.
You likely aren’t showing yet. Most of the uterine growth at this stage is happening deep in the pelvis, well below the belly button. From the outside, your body may look the same even though everything inside is changing rapidly.