At 23 weeks pregnant, your baby measures about 11.4 inches long from head to heel and weighs roughly 1.1 pounds (501 grams). That’s about the size of a grapefruit. While still small enough to fit in the palm of your hand, your baby has grown dramatically from just a few weeks ago and is developing rapidly in ways you can actually start to notice.
Size and Weight at 23 Weeks
The 11.4-inch, 1.1-pound measurement is a head-to-heel estimate, which is the standard way fetal length is tracked from 20 weeks onward. Earlier in pregnancy, measurements are taken from the crown of the head to the rump because the legs are curled tightly against the body. By 23 weeks, the legs are long enough and active enough to factor into a more complete picture.
At this stage, your baby is gaining weight faster than at any previous point. Fat is starting to accumulate under the skin, which has been mostly translucent up until now. Over the coming weeks, that fat layer will fill out your baby’s frame, smooth the wrinkled skin, and help with temperature regulation after birth. Right now, though, your baby is still very lean, with most of the weight coming from bones, organs, and muscle.
What Your Baby Can Do Now
Twenty-three weeks marks a turning point in sensory development. Your baby’s ears have been picking up low-frequency sounds from inside your body since around 18 weeks, things like your heartbeat and the rush of blood through your vessels. Those sounds are muffled, similar to hearing while underwater, because they pass through tissue and amniotic fluid before reaching your baby.
By 22 to 23 weeks, something new happens: your baby may start reacting to your voice. Researchers have observed arm, leg, and head movements in response to a mother’s voice at this stage. Your baby can’t yet distinguish words, but the rhythm and tone of your speech are registering. Loud external sounds, like a door slamming or music played close to your belly, can also trigger a startle response.
Other developments happening around this time include rapid lung maturation. The lungs are producing a substance that will eventually help them inflate with air, though they’re far from ready to breathe independently. Your baby is also swallowing small amounts of amniotic fluid, which helps the digestive system practice. Fingerprints have formed. The brain is growing quickly, building the neural connections that will support more coordinated movement in the weeks ahead.
Why 23 Weeks Matters for Viability
If you’re reading about 23 weeks, you may have come across the term “viability,” the point at which a baby could potentially survive outside the womb with intensive medical support. Twenty-three weeks sits right at that threshold, and survival rates have improved significantly in recent years.
Data from the American Academy of Pediatrics covering 2020 to 2022 shows that 52.8% of all infants born at 23 weeks survived. Among those who received active medical support after birth, the survival rate was 55.1%. That’s a meaningful increase from the numbers reported just a decade earlier and reflects advances in neonatal care.
Survival at this stage, however, comes with significant challenges. Only about 14.4% of babies born at 23 weeks who received medical support survived without serious complications. The median hospital stay was 140 days, nearly five months. Many of these babies went home still needing supplemental oxygen (68.3%) or a heart and breathing monitor (64.6%). By comparison, babies born just one or two weeks later had substantially better outcomes: survival at 24 weeks jumped to 71.1%, and at 25 weeks it reached 82.1%.
Every additional week in the womb at this stage makes a large difference. If you’re at 23 weeks with a healthy pregnancy, the goal is simply to keep going. If you’re facing a medical situation where early delivery is a possibility, knowing these numbers can help you have a more informed conversation with your care team about what to expect.
What You Might Be Feeling
Your uterus is now well above your belly button. A common way providers track growth is by measuring fundal height, the distance from your pubic bone to the top of the uterus. After 20 weeks, that measurement in centimeters roughly matches your week of pregnancy, give or take 2 centimeters. So at 23 weeks, a fundal height of about 21 to 25 centimeters is typical.
You’re likely feeling kicks and rolls more consistently now. Because your baby is still small relative to the space available, movements can feel fluttery or unpredictable, sometimes strong in one spot and barely noticeable the next. As your baby grows over the coming weeks and has less room to move, those kicks will become more distinct and patterned. Many providers suggest starting to pay attention to movement patterns around 28 weeks, but getting familiar with your baby’s activity now gives you a helpful baseline.
Other common experiences at 23 weeks include lower back pain as your center of gravity shifts, mild swelling in your feet and ankles (especially by the end of the day), and round ligament pain, a sharp pulling sensation on the sides of your lower belly when you change positions quickly. Your skin may be stretching visibly across your abdomen, and some people notice new stretch marks appearing around this time.
How Size Can Vary
The 11.4-inch, 1.1-pound average is just that: an average. Babies at 23 weeks can be somewhat larger or smaller and still be perfectly healthy. Factors like genetics, placental function, and whether you’re carrying multiples all influence size. If your provider measures your baby during an ultrasound and the numbers don’t match the textbook average exactly, that’s normal. What matters more is whether your baby is following a consistent growth curve over time, not hitting one specific number at one specific appointment.
Ultrasound estimates of fetal weight also carry a margin of error, often 10 to 15% in either direction. A baby estimated at 1.1 pounds could realistically weigh anywhere from about 0.9 to 1.3 pounds. Your provider will look at the overall trend across multiple measurements rather than placing too much weight on any single reading.