At 25 weeks pregnant, you’re nearing the end of your second trimester with about 15 weeks to go. Your baby is over 13 inches long and weighs close to 2 pounds, roughly the size of a rutabaga. This is a busy stretch: your baby is developing rapidly, your body is shifting to accommodate that growth, and a few important medical screenings fall right around this window.
How Your Baby Is Developing
At 25 weeks, your baby’s lungs are one of the most active construction sites. Specialized cells that produce surfactant, a slippery substance that keeps the tiny air sacs in the lungs from collapsing, begin appearing around 24 weeks. Surfactant production is still limited at this stage, which is a major reason why babies born this early need breathing support. But the groundwork is being laid for the lungs to function independently later.
Your baby’s eyes are also reaching a milestone. The eyelids, which have been fused shut for months, start opening right around 25 to 26 weeks. Once they do, the visual pathways between the eyes and the brain become active. Research published in Developmental Science found that fetuses as young as 26 weeks can detect light shone through the abdomen and even show a preference for face-like patterns of light over random arrangements. That preference is linked to the development of a brain pathway that connects the visual relay center to the cortex.
This is also an active time for movement. A loud noise can make your baby jump or kick, and you might feel occasional hiccups. Movements at 25 weeks can be surprisingly vigorous, though they shouldn’t be painful.
What’s Changing in Your Body
Your uterus has grown well above your belly button by now. From about week 20 onward, the distance from your pubic bone to the top of the uterus (measured in centimeters) roughly matches your weeks of pregnancy, plus or minus two. So at 25 weeks, your provider would expect that measurement to fall between 23 and 27 centimeters.
Back pain is common at this point. The extra weight in front of your body pulls your center of gravity forward, straining your back muscles. At the same time, pregnancy hormones are softening the ligaments in your lower back and pelvis to prepare for delivery, which can leave those joints feeling unstable. Your abdominal muscles are also stretching and weakening, which means your back picks up more of the workload. Walking, swimming, a heating pad, and pregnancy support belts can all help take the edge off.
Many women notice a dark vertical line running down the center of their abdomen by this point. Called the linea nigra, it typically becomes visible around 20 weeks and affects up to 80% of pregnant women. It’s caused by a surge in the hormone that stimulates melanin production, the same hormone responsible for darker areolas and the patchy facial pigmentation some women develop during pregnancy. The line tends to be more pronounced in people with darker skin tones and fades on its own after delivery.
Medical Screenings Around This Time
The gestational diabetes screening usually happens between 24 and 28 weeks, so your provider may schedule it right around now. The most common approach is a two-step process. First, you drink a sugary glucose solution (no fasting required) and have your blood drawn one hour later. If your blood sugar comes back at or below 140 mg/dL, you’re in the clear. If it’s higher, you’ll return for a longer, fasting version of the test where your blood is drawn four times over three hours. A diagnosis of gestational diabetes requires more than one abnormal reading on that second test.
Some practices use a one-step test instead, which involves fasting and a two-hour blood draw. Either way, the process is straightforward, and most women pass without any issues.
The Tdap vaccine (which protects against whooping cough) is recommended a bit later, between weeks 27 and 36, ideally on the earlier end. So you’re not quite in that window yet, but it’s worth knowing it’s coming soon.
What Happens if a Baby Is Born at 25 Weeks
Twenty-five weeks falls within what doctors consider the zone of viability. With intensive care, about 80% of babies born at 25 or 26 weeks survive. That number has improved significantly over the past few decades, but survival at this stage still comes with real risks.
About 1 in 3 babies born this early develop chronic lung disease from needing prolonged breathing support. Roughly 1 in 10 experience a significant brain injury, and a similar proportion develop serious eye problems that may require laser treatment. Bowel infections affect about 1 in 20.
Among survivors, about 1 in 10 develop cerebral palsy, and roughly 1 in 15 have a severe learning disability. These aren’t meant to be alarming numbers for someone at 25 weeks with a healthy pregnancy. But if preterm birth is a concern for any reason, knowing the landscape can help you have more informed conversations with your care team.
Your Baby’s Movement Patterns
At 25 weeks, most women feel their baby move regularly, though the timing and intensity vary. You might notice more activity after you eat, when you lie down at night, or in response to sudden sounds. The movements can feel like kicks, rolls, or rhythmic tapping (hiccups). Formal kick counting, where you track how long it takes to feel 10 movements, is typically recommended starting around 28 weeks. For now, getting familiar with your baby’s general patterns is the most useful thing you can do.