At 11 weeks pregnant, your baby is about the size of a golf ball. From head to bottom (called crown-to-rump length), that’s roughly 1.5 inches (4.2 to 5.3 centimeters), and your baby weighs about 1.6 ounces (46 grams). This is the tail end of the first trimester, and your baby has shifted from a tiny cluster of cells into something that looks unmistakably human.
How 11-Week Size Is Measured
At this stage, your baby is curled into a C-shape, so doctors measure from the top of the head to the bottom of the torso rather than head to toe. This crown-to-rump length grows steadily throughout the week. At 11 weeks 0 days, the measurement is typically around 42 to 43 millimeters. By 11 weeks 6 days, it reaches 52 to 53 millimeters. That may sound like a small difference, but at this pace your baby is growing roughly a millimeter and a half per day.
If you have an ultrasound around this time, the technician uses this measurement to confirm or adjust your due date. It’s the most accurate way to estimate gestational age in the first trimester, more reliable than counting from your last period.
What Your Baby Looks Like Now
Your baby’s face is becoming more recognizable. The eyes, which started on the sides of the head, have moved closer together toward the front. Ears are nearly in their final position. Facial features are more prominent than they were even a week ago, though the head is still disproportionately large compared to the body.
The fingers and toes are now fully separated. Just a week or so earlier, they were still webbed. Your baby’s skin is completely see-through at this point, so if you could look closely, you’d see developing blood vessels and the outlines of bones underneath. Those bones are just beginning to harden. In fact, the skull bones are only now reaching the point where they can be reliably seen on ultrasound. The skeleton is transitioning from soft cartilage to actual bone tissue, a process that will continue well beyond birth.
Movement You Can’t Feel Yet
One of the most exciting developments at 11 weeks is movement. Your baby’s nerves and muscles have started working together, producing small, jerky motions. The elbows, knees, and ankles are functional. Your baby is opening and closing tiny fists and experimenting with mouth movements.
You won’t feel any of this yet. At just over an inch long, your baby is far too small to produce sensations you’d notice. Most first-time mothers don’t feel movement until 18 to 22 weeks. But on an ultrasound, you may be able to see your baby wiggling, stretching, or even hiccupping. It’s one of the reasons an 11-week scan can feel surprisingly exciting.
What’s Happening Inside
Beyond what you can see on a screen, a lot of internal development is underway. The major organs formed during weeks 5 through 10, and now they’re refining and growing. The intestines, which temporarily extended into the umbilical cord because the abdomen was too small to hold them, are beginning to move back into the body. The liver is producing red blood cells. The kidneys are starting to function, producing small amounts of urine.
Your baby’s reproductive organs are also developing, though it’s still too early to determine sex on ultrasound. That typically becomes possible around 18 to 20 weeks.
The First-Trimester Scan
If your provider offers a first-trimester screening, it usually happens between 11 and 14 weeks, so you may be scheduling one right around now. Part of this scan involves measuring a small pocket of fluid at the back of your baby’s neck. This fluid collection is normal in every fetus, but its thickness can help estimate the chance of certain genetic conditions, including Down syndrome. A measurement up to 3 millimeters is considered low risk.
This scan is optional and isn’t diagnostic on its own. It gives a risk estimate, not a definitive answer. If the measurement is higher than expected, your provider will discuss follow-up options like further blood work or more detailed testing. Many babies with slightly elevated measurements turn out to be perfectly healthy.
Putting the Size in Perspective
A golf ball or ping-pong ball is the comparison you’ll see most often for 11 weeks, and it’s a good one. Your baby is small enough to fit comfortably in the palm of your hand, yet complex enough to have working joints, individual fingers, and a face you’d recognize as human. Over the next few weeks, growth accelerates dramatically. By week 14, your baby will have nearly doubled in length, and by the end of the second trimester, that 1.5-inch body will be closer to 14 inches.
For now, at 11 weeks, the foundation is set. The organs are in place, the bones are hardening, and your baby is already practicing the movements you’ll eventually feel as kicks and rolls months from now.