At 27 weeks, you’re right at the boundary between the second and third trimesters, and this is a week where several important things converge: your baby is hitting major developmental milestones, your body is shifting into late-pregnancy mode, and there are specific medical screenings and vaccines to take care of. Here’s what deserves your attention right now.
What Your Baby Is Doing This Week
Your baby weighs about 2¼ pounds and measures roughly 13¾ inches long, about the size of a head of cauliflower. The lungs recently started producing surfactant, a substance your baby will need to breathe independently after birth. This week, your baby can open and close their eyes and has developed eyelashes. Brain activity is ramping up significantly, with regular sleep and wake cycles becoming more defined. You may notice patterns in when your baby is active versus quiet, and those patterns will only get more distinct over the coming weeks.
Physical Changes to Expect
The third trimester brings a new set of sensations that can feel alarming if you’re not expecting them. Braxton Hicks contractions are common around this time. These are mild tightening feelings across your belly that come and go without a regular pattern. They tend to show up in the afternoon or evening, especially after physical activity or sex, and they’ll become more frequent as your due date approaches. They’re your uterus practicing for labor, not a sign that anything is wrong.
Shortness of breath is another hallmark of this stage. Your growing uterus is pushing up against your rib cage, reducing the space your lungs have to expand. You might get winded climbing stairs or doing things that never bothered you before. Sleeping on your back can make this worse. If you haven’t already, switching to side sleeping (your left side is ideal) helps both your breathing and blood flow to the baby. A pillow between your knees and one tucked under your belly can make side sleeping more comfortable. Lying flat on your back puts pressure on the large vein that returns blood from your lower body to your heart, which can cause dizziness and reduce blood flow to the baby.
Start Tracking Fetal Movement
By 27 weeks, your baby’s movements are strong enough and consistent enough that you can start paying attention to patterns. Kick counting is straightforward: pick a time when your baby is typically active, sit or lie down, and count any kicks, flutters, swishes, or rolls. You’re looking for 10 movements within two hours. Most people feel 10 movements well within an hour.
You don’t necessarily need to do a formal count every day at this stage, but getting familiar with your baby’s normal activity level matters. If movements suddenly change, slow down dramatically, or stop, contact your provider. A quiet period doesn’t always mean something is wrong (babies sleep in 20- to 40-minute stretches), but a noticeable shift from your baby’s usual pattern is worth a phone call.
Medical Screenings Happening Now
If you haven’t already done your glucose screening test, it’s likely happening this week or very soon. Most pregnant women are screened for gestational diabetes between 24 and 28 weeks. The test itself is simple: you drink a sweet glucose solution, wait one hour, and have your blood drawn. You don’t need to fast or change your diet beforehand. If your blood sugar comes back higher than the threshold, you’ll be asked to do a longer, more detailed follow-up test. Gestational diabetes is manageable, but catching it now means you can adjust your diet and monitoring before it affects your baby’s growth.
This is also the ideal window for the Tdap vaccine, which protects against whooping cough. The CDC recommends getting it between 27 and 36 weeks of each pregnancy, with earlier in that window being better. When you get vaccinated during pregnancy, your body produces antibodies that cross the placenta and give your baby protection during the first few months of life, before they’re old enough for their own vaccinations. This is recommended with every pregnancy, even if you’ve had the shot before.
Nutrition Worth Focusing On
Your baby’s skeleton is hardening and their blood volume is increasing rapidly, which means your need for iron and calcium is at its peak. The World Health Organization recommends 30 to 60 mg of supplemental iron daily throughout pregnancy to reduce the risk of anemia and low birth weight. Most prenatal vitamins contain iron, but if you’ve been told your levels are low, your provider may suggest an additional supplement. Iron absorbs better when taken with vitamin C and away from calcium-rich foods or dairy, so timing matters.
Beyond supplements, this is a good time to make sure your daily eating supports the energy demands of the third trimester. Your calorie needs have increased by roughly 300 to 450 calories per day compared to pre-pregnancy. Protein, fiber, and foods rich in omega-3 fatty acids (like salmon, walnuts, and chia seeds) all support both your baby’s brain development and your own energy levels during a trimester that can feel physically draining.
Practical Tasks for This Week
You’re entering the window where preparation starts shifting from fun to urgent. If you’ve been designing or setting up a nursery, now is the time to wrap that up while you still have the energy and mobility to do it comfortably. You have a few more weeks before the bigger logistics need attention (packing a hospital bag, installing a car seat, choosing a pediatrician all typically happen between weeks 32 and 36), but getting the nursery furniture assembled and the room functional now means one less thing competing for your attention later.
Other things worth doing in the next few weeks: finalize your birth preferences and discuss them with your provider, look into childbirth and breastfeeding classes if you haven’t taken them, and start thinking about your postpartum support plan. If you’re planning to take parental leave, confirm the paperwork timeline with your employer. Many of these tasks feel like they can wait, but the third trimester has a way of moving faster than expected, especially if fatigue or complications slow you down.
Signs That Need Immediate Attention
At 27 weeks, your baby is viable outside the womb but would need intensive medical support, so recognizing signs of preterm labor is important. The key symptoms to watch for are regular or frequent contractions (not the random, irregular Braxton Hicks), a constant dull backache in your lower back, pelvic pressure that feels different from the usual heaviness, vaginal spotting or bleeding, and any gush or steady trickle of fluid. Fluid that’s watery, bloody, or mucus-like can signal that your membranes have ruptured. Any of these warrant an immediate call to your provider or a trip to labor and delivery. Preterm labor caught early can sometimes be slowed with medical intervention, and every additional day in the womb at this stage makes a meaningful difference for your baby’s lungs and brain.