At 25 weeks pregnant, your baby measures roughly 13 to 14 inches long from head to heel and weighs about 1.5 pounds (around 680 grams). That’s about the size of a papaya. Your baby has gone from a cluster of cells to a recognizably human form with functioning senses, developing lungs, and increasingly coordinated movement.
Length, Weight, and Proportions
At this stage, your baby’s body is becoming more proportional. Earlier in pregnancy, the head made up a much larger share of overall size, but by 25 weeks the limbs and torso have caught up considerably. The legs are now curled up in the classic fetal position, which is why ultrasound measurements sometimes look shorter than the full head-to-heel length. If your provider mentions “crown-to-rump” length, that measurement only covers the top of the head to the base of the spine, so it will be several inches shorter than the total length.
Weight gain accelerates from here. Your baby will roughly double or triple in weight over the next 10 weeks as fat deposits build up under the skin. Right now, your baby is still lean, with wrinkled, somewhat translucent skin. A waxy coating called vernix covers the skin to protect it from the amniotic fluid, and fine hair called lanugo helps that coating stick in place.
What Your Baby Can Do at 25 Weeks
Your baby’s senses are coming online. At 25 weeks, your baby can hear sounds from outside the womb and may move in response to familiar ones, like your voice. The eyes are still closed most of the time, but rapid eye movement (REM) sleep is already happening, meaning the eyes dart around beneath closed lids just as they do during dreaming sleep in adults. Most of your baby’s sleep time at this point is spent in REM.
You’re likely feeling kicks, rolls, and jabs, though the pattern may still be unpredictable. Fetal movement often doesn’t settle into a consistent routine until around 28 weeks. Babies in the womb cycle between sleep and wakefulness, and a sleep period can last up to 40 minutes, during which you may feel nothing at all. Many babies are most active at night or when you’re resting, which is partly why movement feels more noticeable when you lie down.
Lung and Organ Development
The lungs are one of the last major organs to mature, and 25 weeks marks a critical window. The tiny air sacs are forming, and the cells lining them are beginning to differentiate into two types: thin cells that will handle gas exchange (getting oxygen into the blood) and specialized cells that produce surfactant, a slippery substance that keeps the air sacs from collapsing each time your baby takes a breath. Surfactant production starts around 24 weeks but won’t reach full capacity for several more weeks. This is a major reason why extremely premature babies often need breathing support.
Blood vessels are also branching deeper into the lung tissue during this stage, forming the network of tiny capillaries that will eventually sit right next to the air sacs. The closer these capillaries get to the air spaces, the more efficiently oxygen can pass into the bloodstream after birth.
What 25 Weeks Means for Viability
If a baby is born at 25 weeks, survival rates have improved dramatically over the past few decades. A Stanford Medicine study of nearly 11,000 babies born between 22 and 28 weeks (from 2013 to 2018) found significant improvements in survival compared to earlier eras. In the mid-1980s, babies born at 25 weeks and weighing around 500 grams rarely survived. Today, the outlook is far better, though a stay in the neonatal intensive care unit is expected.
Long-term outcomes vary. Among babies born between 22 and 26 weeks, about half showed mild or no neurodevelopmental problems by age 2. Around 29% had moderate disabilities, and about 21% had severe impairments. Roughly 8% developed moderate to severe cerebral palsy, and about 15% needed a mobility aid such as a brace or walker. About half were rehospitalized at least once after their initial NICU discharge. These numbers cover a range of gestational ages, and outcomes generally improve with each additional week in the womb.
How Your Body Is Changing
Your uterus has grown well past your belly button by now. Fundal height, the distance from your pubic bone to the top of your uterus, should roughly match your week of pregnancy in centimeters, give or take 2 centimeters. So at 25 weeks, a measurement between 23 and 27 centimeters is typical. Your provider may start checking this at each visit as a simple way to track your baby’s growth.
You may notice your belly feeling tighter or experiencing occasional painless contractions. These are Braxton Hicks contractions, your uterus practicing for labor. They’re irregular and usually go away with a change in position or activity. The growing uterus also puts more pressure on your bladder and lower back, which is why many people at 25 weeks notice more frequent trips to the bathroom and increasing back discomfort.
Movement Tracking at This Stage
Most providers don’t ask you to do formal kick counts until 28 weeks, when fetal movement becomes more predictable. But at 25 weeks, you’re building familiarity with your baby’s general rhythms. You might notice more activity after meals, during the evening, or when you’re sitting or lying still. If you go a stretch without feeling movement and want reassurance, try drinking something cold and lying on your side for 30 to 40 minutes. Your baby may simply be in a sleep cycle that can last up to 40 minutes before activity resumes.