At 8 weeks pregnant, your baby measures roughly 16 to 22 millimeters from head to bottom, or about half an inch to just under an inch. That’s comparable in size to a raspberry or kidney bean. Despite being tiny enough to sit on your fingertip, your baby is in the middle of a dramatic stretch of development, with major organs forming and a heart already beating fast.
How Big Is the Baby, Exactly?
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 the start of week 8, that measurement is about 16 mm. By the end of the week, it reaches around 22 mm. In more familiar terms, that’s roughly 0.6 to 0.9 inches.
Weight at this stage is almost negligible. The embryo weighs about 1 gram, or around 0.04 ounces. For comparison, a single paperclip weighs about a gram. Your baby will gain weight much more noticeably in the coming weeks once the basic body plan is in place and growth shifts into higher gear.
What’s Forming at 8 Weeks
Week 8 is a milestone because all of the major organs and body systems are now developing simultaneously. The hands and feet are present but still webbed, looking a bit like tiny paddles. Eyes are becoming visible, and ears are starting to take shape. The spine is still longer than the rest of the body, giving the embryo a slight tail-like curve that will disappear over the next few weeks as the body catches up in length.
On ultrasound, the embryo at this stage has what sonographers sometimes call a “gummy bear appearance,” with a recognizable head, trunk, and small limb buds branching off. It doesn’t look like a baby yet, but it’s clearly starting to take on a human form. If you have an early ultrasound around this time, you’ll likely see the yolk sac (a small round structure that provides nutrients before the placenta takes over) and a flickering heartbeat.
The Heartbeat at 8 Weeks
Your baby’s heart has been beating since around week 6, but by week 8 it has sped up considerably. The typical heart rate at this point is 145 to 170 beats per minute, which is roughly twice as fast as your own resting heart rate. This rapid pace is normal for an embryo this size and reflects how hard the tiny cardiovascular system is working to supply blood to rapidly growing tissues. The rate will plateau and slow slightly after about 9 weeks, settling into the 137 to 144 range.
Changes in Your Body
Even though your baby is smaller than a grape, your uterus has already expanded to about the size of a tennis ball. Before pregnancy, it’s closer to the size of a small pear. You won’t have a visible bump yet at 8 weeks (the uterus is still tucked behind your pelvic bone), but you may notice your waistband feeling tighter, along with bloating that makes pants less comfortable than usual.
This is also the window when pregnancy symptoms like nausea, breast tenderness, and fatigue tend to be at their most intense. The hormonal surge driving all of that embryonic development is the same one responsible for how you’re feeling. For most people, these symptoms begin to ease as the first trimester winds down around weeks 12 to 14.
How Growth Changes From Here
Week 8 marks the tail end of the embryonic period. Starting at week 9, your baby is officially called a fetus, and the focus shifts from forming new organs to growing and refining the ones already in place. The webbing between fingers and toes disappears, facial features become more defined, and the body starts to lengthen and straighten out. By week 12, your baby will be about 2.5 inches long, roughly the size of a lime, and will have more than tripled in length from where it is now.
Growth during these early weeks isn’t perfectly uniform from one pregnancy to the next. A few millimeters of difference in crown-rump length is completely normal and doesn’t indicate a problem. Ultrasound measurements at this stage are most useful for confirming your due date, since embryos grow at a remarkably predictable rate during the first trimester.