At 25 weeks pregnant, your baby measures roughly 13 to 14 inches long from head to heel and weighs about 1.5 pounds. That’s about the size of a papaya. Your baby is still lean and wrinkled, but significant development is happening beneath the surface, particularly in the lungs and brain.
Size, Weight, and Appearance
At this stage, your baby’s skin is thin and somewhat translucent. Blood is visible through the capillaries because there’s very little fat underneath the skin yet, which also explains the wrinkled appearance. Over the coming weeks, your baby will start packing on fat rapidly, filling out that loose skin and gaining the ability to regulate body temperature outside the womb.
Your own body reflects this growth. The top of your uterus (called the fundal height) is now roughly 23 to 27 centimeters above your pubic bone. As a general rule, fundal height in centimeters tracks closely with your week of pregnancy, give or take about two centimeters. Your provider may measure this at your prenatal visits to confirm your baby is growing on track.
What Your Baby Can Do Now
Twenty-five weeks is a busy time for sensory development. Your baby responds to both touch and sound. A sudden loud noise can trigger a startle response, meaning you might feel a sharp kick or jolt in reaction. Your baby may also move in response to your voice, so this is a stage where some parents start noticing that talking, singing, or playing music seems to get a reaction.
You’re likely feeling more defined movements now compared to the subtle flutters of earlier weeks. Kicks, rolls, jabs, and swishes are all normal. Your baby has sleep-wake cycles much like yours, with periods of rest followed by bursts of activity. Many people notice increased movement after eating (likely from the rise in blood sugar) and in the evening when you’re lying still. Babies also tend to be more active at night, possibly because your daytime movement rocks them to sleep.
Formal kick counting is generally recommended starting around 28 weeks, but getting familiar with your baby’s patterns now can be helpful. When the time comes, the goal is to feel 10 movements within two hours.
Lung Development at 25 Weeks
Your baby’s lungs are one of the last organs to fully mature, and at 25 weeks they’re in an important growth phase. The specialized cells responsible for producing surfactant, a substance that keeps the tiny air sacs in the lungs from collapsing, have been developing since around 20 weeks. By now, these cells are increasing in both number and maturity, and surfactant production is gradually ramping up.
Full lung maturity, where a baby can breathe reliably without assistance, typically isn’t reached until around 36 weeks. But 25-week lungs are capable of basic gas exchange. This matters because if your baby were born now, medical support could help bridge the gap until the lungs catch up.
Survival If Born Early
At 25 weeks, a baby is considered viable but extremely premature. A study published in 2024 analyzing outcomes from 2020 to 2022 found that survival for infants born at 25 weeks and treated in a neonatal intensive care unit was approximately 82%. That’s a significant improvement over earlier gestational ages (survival at 22 weeks, by comparison, was around 25%). These outcomes depend heavily on access to a high-level NICU and the individual circumstances of the birth.
Babies born this early face weeks to months of intensive care and a higher risk of long-term complications, but the majority do survive with modern medical support.
Common Screening Around This Time
If you haven’t already, you’ll likely have a glucose screening test sometime between 24 and 28 weeks. This checks for gestational diabetes by measuring how your body processes sugar after drinking a glucose solution. At 25 weeks, you’re right in the middle of that window, so don’t be surprised if your provider schedules it at your next visit. The test may be done earlier if you have risk factors or if sugar has shown up in your urine at previous appointments.
What to Expect in the Coming Weeks
Between now and 28 weeks, your baby will gain weight quickly, possibly doubling in size. Fat will start filling in under the skin, smoothing out wrinkles and giving your baby the rounder appearance you’d expect at birth. The lungs will continue maturing, the brain will develop more complex folds and connections, and movements will become stronger and more coordinated. By the time you hit the third trimester at 28 weeks, your baby’s activity patterns will be established enough that tracking kicks becomes a useful tool for monitoring wellbeing.