At 8 weeks pregnant, your baby is about the size of a raspberry, measuring roughly 14 to 16 millimeters from head to rump. This is the final week your developing baby is officially classified as an embryo. Starting next week, it transitions to being called a fetus, a milestone that reflects just how much formation has already taken place.
What Your Baby Looks Like Now
By week 8, the embryo has developed a recognizable shape with a curved body and distinct head, trunk, and limb buds. Ultrasound technicians sometimes describe it as having a “gummy bear appearance.” The fingers and toes are separating into individual digits this week, and wrists are becoming defined. Facial features are rapidly taking shape too: the nose, eyes, and external ears are forming, and eyelids are beginning to develop.
Inside, the brain is undergoing intense activity. Nerve cells have started migrating from where they’re produced to their permanent positions in the central nervous system. The innermost layer of the brain’s outer structure, the cortex, is forming right now. This migration process started around week 6 and will continue for months, but this early phase lays the groundwork for all future brain function.
The Heartbeat at 8 Weeks
Your baby’s heart has been beating for a couple of weeks already, but by week 8 it’s significantly faster. The heart rate typically ranges from 145 to 170 beats per minute, up from around 100 to 115 beats per minute before week 6. If you have an ultrasound this week, the heartbeat is clearly visible and often audible.
Hearing that heartbeat carries real statistical weight. Once a heartbeat is confirmed at 8 weeks, the chance of the pregnancy continuing is about 98%. That number climbs to 99.4% by week 10. While nothing is guaranteed, the risk of miscarriage drops meaningfully with each passing week once cardiac activity is established.
What You Might Be Feeling
Week 8 is often when pregnancy symptoms are in full force. Rising hormone levels are behind most of what you’re experiencing, and those hormones are peaking right around now. Your hCG levels (the hormone pregnancy tests detect) are somewhere between 31,000 and 149,000 mIU/mL, a massive jump from just a few weeks ago.
The most common symptoms at this stage include:
- Nausea: Morning sickness typically starts between weeks 4 and 9 and can hit at any time of day. It’s driven by those surging hormone levels and tends to peak over the next few weeks before improving for most people in the second trimester.
- Fatigue: Rising progesterone levels make you feel exhausted in a way that sleep doesn’t fully fix. This is one of the earliest and most persistent first-trimester symptoms.
- Breast tenderness: Your breasts may feel swollen, sore, or unusually sensitive. Hormonal shifts are increasing blood flow and changing breast tissue in preparation for milk production.
- Frequent urination: Your blood volume is increasing, which means your kidneys are filtering more fluid. The result is more trips to the bathroom, even though your uterus isn’t yet large enough to press on your bladder.
- Constipation and heartburn: Progesterone relaxes smooth muscle throughout your body, including your digestive tract. Food moves more slowly, and the valve between your stomach and esophagus doesn’t close as tightly, letting acid creep up.
- Food cravings or aversions: You may suddenly find certain foods repulsive or develop intense cravings for things you’d normally ignore. Both are hormone-driven and completely normal.
Not everyone experiences all of these, and the intensity varies widely. Some people have debilitating nausea while others feel mostly fine. Neither scenario says anything about the health of your pregnancy.
Your First Prenatal Visit
Many people have their first prenatal appointment around week 8. This visit is longer and more thorough than the ones that follow. Expect a panel of blood tests covering your blood type and Rh factor, a complete blood count, and screening for infections including hepatitis B, hepatitis C, HIV, rubella, and other sexually transmitted infections. You’ll also provide a urine sample to check for urinary tract infections and other markers.
Your Rh factor matters because if your blood is Rh-negative and the baby’s is Rh-positive, your body could produce antibodies against the baby’s blood cells. Identifying this early allows your care team to prevent complications with a simple treatment later in pregnancy.
If an ultrasound is performed at this appointment, you’ll see the embryo’s overall shape, the flickering of the heartbeat, and likely the yolk sac, a small circular structure that has been nourishing your baby since before the placenta took over. Your provider will measure the crown-rump length to confirm your due date. At 8 weeks, that measurement typically falls between about 10 and 19 millimeters depending on exact gestational age.
What’s Happening With Your Body
Your uterus is expanding but hasn’t risen above your pelvic bone yet, so most people aren’t visibly showing. It’s roughly the size of a large orange at this point, double what it was before pregnancy. Some people notice their pants fitting tighter, but that’s more often from bloating than actual uterine growth pushing outward.
Behind the scenes, your body is building an entirely new blood supply system. Your blood volume is already increasing, and your heart is pumping harder to keep up. This extra cardiovascular effort contributes to the fatigue you’re feeling and can occasionally cause dizziness if you stand up too quickly. Staying hydrated helps, since your body needs significantly more fluid than usual to support the expanding blood volume and amniotic fluid production.
The Embryo-to-Fetus Transition
Week 8 marks the end of the embryonic period. During these first 8 weeks after fertilization, every major organ system has been established in at least a rudimentary form. The heart is beating, the brain is actively wiring itself, the digestive tract has a basic structure, and the limbs have differentiated into arms with hands and legs with feet. Starting at week 9, your baby is classified as a fetus, and the focus shifts from forming new organs to growing and refining the ones already in place.
This distinction matters practically because the embryonic period is when the developing baby is most vulnerable to disruptions in organ formation. Moving into the fetal period doesn’t eliminate all risk, but the most critical window for structural development is closing.