At 25 weeks, a baby measures about 13.6 inches (34.6 cm) from head to heel and weighs roughly 1.5 pounds (660 grams). That’s about the size of a papaya. While still small enough to fit in two cupped hands, your baby has grown substantially from the early weeks of pregnancy and is putting on body fat that will continue to fill out their frame over the next trimester.
Weight and Length at 25 Weeks
The average 25-week fetus weighs around 660 grams, or just under 1.5 pounds. Length from the top of the head to the heel is approximately 34.6 centimeters (about 13.6 inches). To put that in perspective, the baby has roughly tripled in length since week 12, when most parents have their first ultrasound.
These numbers represent averages. Individual babies vary based on genetics, placental function, and other factors. Your provider may measure specific body parts on ultrasound to assess growth. Two common measurements at this stage are the abdominal circumference, which averages about 200 millimeters (roughly 8 inches around), and the thighbone length, which averages about 45.5 millimeters (just under 2 inches). A normal range spans roughly 10% above or below those figures.
What Your Baby Looks Like Right Now
At 25 weeks, your baby is starting to look more like a newborn than the translucent, wrinkled figure of earlier ultrasounds. Body fat is building up beneath the skin, making it less wrinkled and more plump. Earlier in pregnancy, the skin was reddish and see-through enough that veins were visible underneath. By now, that’s changing as fat deposits smooth things out.
The baby is still covered in lanugo, a fine peach-fuzz hair that acts as insulation and protection. Their nervous system is maturing quickly this week. Melanin, the pigment that gives skin and eyes their color, starts being produced around week 26, so that process is just getting underway. The eyes aren’t open yet at 25 weeks, but that milestone comes soon: by week 27, babies can open their eyes, blink, and even have eyelashes.
How Movement Feels at 25 Weeks
Between 25 and 28 weeks, your baby’s movement patterns shift noticeably. Earlier in pregnancy, you may have felt flutters, turns, and full-body rolls. Around this stage, the baby starts doing more kicking and stretching, with less of the dramatic flipping and twisting. Movements feel more like squirming or jerking as the baby grows bigger relative to the space available.
If you haven’t already been paying attention to movement patterns, this is a natural time to start noticing when your baby tends to be active. Most babies develop a rhythm of active and quiet periods. You don’t need to count kicks at this point unless your provider asks you to, but becoming familiar with your baby’s normal activity makes it easier to notice if something changes later.
How Your Body Reflects the Growth
Your uterus is growing in step with the baby. Healthcare providers track this by measuring fundal height, the distance from your pubic bone to the top of your uterus. After 20 weeks, fundal height in centimeters roughly matches the number of weeks pregnant you are. At 25 weeks, that measurement should be close to 25 centimeters (about 10 inches), give or take 2 centimeters. If it’s significantly higher or lower, your provider may order an ultrasound to check the baby’s size and fluid levels more precisely.
If a Baby Is Born at 25 Weeks
Some parents searching for their baby’s size at 25 weeks are facing the possibility of premature birth. At this stage, a baby born with access to intensive neonatal care has about an 80% chance of survival. That’s a meaningful number, but it comes with significant medical challenges along the way.
About half of babies born at 25 weeks develop a chronic lung condition from needing breathing support early on. Roughly 1 to 2 in 10 experience a significant early brain problem, and a similar proportion need laser treatment for an eye condition caused by abnormal blood vessel growth. Serious bowel infections affect about 1 in 15 babies born this early.
Among those who survive, about 1 in 10 are later diagnosed with cerebral palsy, and about 1 in 15 have a severe learning disability. These numbers mean the majority of 25-week survivors grow up without severe impairments, though many need developmental follow-up through early childhood. The weeks that follow 25 are critical: each additional week in the womb substantially improves outcomes across the board.
What Changes in the Coming Weeks
Growth accelerates from here. Over the next 15 weeks, your baby will gain roughly 6 more pounds and grow another 6 to 8 inches in length. The fat stores being laid down now serve a crucial purpose: they’ll help regulate body temperature after birth. By week 28, the brain will have developed enough to begin controlling body temperature and rhythmic breathing movements on its own. The lungs are the last major organ to mature, a process that continues well into the third trimester.
At 25 weeks, you’re at the boundary between the second and third trimesters. Your baby is fully formed in miniature, with all organs present and functioning at a basic level. The remaining weeks are about growth, maturation, and building the reserves needed for life outside the womb.