At 8 weeks pregnant, your baby is about the size of a kidney bean, measuring roughly half an inch long (1.6 cm) and weighing just 0.04 ounces (about 1 gram). Despite being tiny enough to sit on your fingertip, your baby has already undergone enormous changes and is on the verge of a major developmental milestone.
Size Comparisons That Help
Half an inch is hard to picture on its own, so food comparisons are popular for good reason. At 8 weeks, your baby is close in size to a kidney bean or a single raspberry. That 0.04-ounce weight is essentially nothing you could feel in your hand, yet it represents a dramatic increase from just a few weeks earlier, when the embryo was barely visible to the naked eye.
Your uterus, meanwhile, has already grown to roughly the size of a tennis ball to accommodate the gestational sac, even though the embryo itself is so small. That expanding uterus is part of why you may notice bloating or a feeling of fullness in your lower abdomen, even though there’s no visible bump yet.
What Your Baby Looks Like Right Now
At 8 weeks, the embryo looks like a small oblong shape with a large head relative to its body. Arms and legs have started forming as tiny buds, and the hands and feet are webbed with the earliest version of fingers and toes. The “tail” that was visible in earlier weeks is almost gone.
The heart has been beating since around week 5 or 6, and by now it’s pumping at a rapid pace. On an ultrasound, you may be able to see or even hear that heartbeat flickering on screen. Your provider will also look for the gestational sac (the fluid-filled space surrounding your baby) and the yolk sac, a small bubble-like structure that provides nutrients until the placenta fully takes over.
The Embryo-to-Fetus Transition
Week 8 marks the final stretch of the embryonic period. For the first 8 weeks after fertilization, your baby is technically classified as an embryo. Starting at week 9, the term changes to fetus. This isn’t just a naming convention. It reflects the fact that by the end of week 8, the basic structure of every major organ system has been laid down. From this point forward, development shifts from building new structures to growing and refining the ones already in place.
What You Might Be Feeling
Eight weeks falls squarely in the window when first-trimester symptoms tend to peak. Nausea, commonly called morning sickness, typically starts between weeks 4 and 9, driven by rapidly rising hormone levels. Despite the name, it can strike at any time of day.
Progesterone, one of the key hormones sustaining the pregnancy, is responsible for several of the less glamorous symptoms at this stage. It slows digestion, which can cause constipation and heartburn. It also contributes to the deep fatigue many people feel during the first trimester. Breast tenderness, food aversions, and heightened sensitivity to smells are all common right now as well.
Not everyone experiences all of these, and some people have very mild symptoms at 8 weeks. Both scenarios are normal. Symptom intensity doesn’t reliably predict how the pregnancy is progressing.
What Happens at an 8-Week Ultrasound
Many providers schedule a first ultrasound around this time, sometimes called a dating scan. The main goals are to confirm the pregnancy is located in the uterus, check for a heartbeat, and estimate how far along you are based on the embryo’s measurements. At this stage, the ultrasound is often done transvaginally because the embryo is still too small to see clearly through the abdomen.
You’ll likely see what looks like a small bean-shaped figure inside a dark circle (the gestational sac). The yolk sac may appear as a smaller bright ring nearby. If the timing is right, your provider can point out the arm and leg buds and measure the embryo from one end to the other, a measurement called crown-rump length, which helps pin down your due date.
Nutrition and Caffeine at This Stage
Because all of your baby’s major organ systems are forming during these early weeks, what you eat and drink matters more than it might seem for something the size of a bean. A prenatal vitamin with folic acid is especially important right now to support neural tube development.
If you rely on coffee to get through the fatigue, you don’t have to quit entirely. Both the American College of Obstetricians and Gynecologists and the American Pregnancy Organization recommend staying under 200 milligrams of caffeine per day. That’s roughly one 12-ounce cup of brewed coffee. Keep in mind that total includes caffeine from tea, chocolate, soda, and any supplements or medications that contain it, so it adds up faster than you might expect.