Twenty-eight weeks marks the official start of the third trimester of pregnancy. You’re now two-thirds of the way through, with roughly 12 weeks left until your due date. This is a significant milestone for both you and your baby: the baby has reached a size and developmental stage where survival outside the womb is highly likely if early delivery becomes necessary, and your body is shifting into the final stretch of preparation.
Your Baby at 28 Weeks
At 28 weeks, the average baby measures about 25 cm (9.8 inches) from crown to heel and weighs around 1,000 grams, or 2.2 pounds. That’s roughly the size of a large eggplant. The brain is developing rapidly, adding billions of neurons and forming the grooves and folds that characterize a mature brain. The lungs are producing surfactant, a substance that will help the air sacs inflate after birth. The eyes can open and close, and the baby responds to light filtering through the uterine wall.
Movements are strong and frequent at this stage. You’ll likely feel distinct kicks, rolls, and hiccups rather than the subtle flutters of earlier weeks. This is a good time to start paying attention to your baby’s movement patterns. The Cleveland Clinic recommends two simple approaches to tracking kicks: count how many movements you feel in one hour, or time how long it takes to feel 10 movements. By 28 weeks, you should have a general sense of when your baby is most active, which makes it easier to notice if something changes.
Why 28 Weeks Matters for Viability
If a baby is born at 28 weeks, survival rates fall between 80 and 90 percent. Only about 10 percent of babies born at this gestational age develop long-term health problems. Those numbers represent a dramatic improvement over earlier weeks. A 28-week baby would still need weeks of intensive care to support breathing, temperature regulation, and feeding, but the odds are strongly in their favor. This is one reason providers consider the 28-week mark a meaningful threshold in prenatal care.
Common Symptoms in the Third Trimester
Entering the third trimester brings a new wave of physical changes. Some are familiar from earlier in pregnancy, and some are brand new.
Braxton Hicks contractions are mild tightening sensations across your abdomen. They tend to show up in the afternoon or evening, especially after physical activity. They’re irregular and usually painless, though they can catch you off guard the first time you feel one. These become more frequent as you get closer to your due date.
Back pain is one of the most common complaints. Pregnancy hormones loosen the connective tissue in your pelvis, while the growing uterus stretches your abdominal muscles. Together, those changes shift your center of gravity and put extra strain on your lower back.
Shortness of breath happens because your uterus is pushing up against your diaphragm, reducing the space your lungs have to expand. You may find it harder to breathe when lying on your back. Sleeping on your side often helps. Your body also increases its breathing rate during this period, so you may get winded more easily during everyday activities.
Heartburn and constipation both tend to worsen in the third trimester. Hormones slow down your digestive system, and the growing uterus presses directly on your intestines. Smaller, more frequent meals can ease heartburn, and staying hydrated helps with constipation.
Other common symptoms include heart palpitations (a fluttering feeling in your chest caused by changes in blood flow), more frequent urination as the baby presses on your bladder, and visible vein changes like spider veins on your face and neck or varicose veins in your legs. Most of these resolve after delivery.
Tests and Screenings Around 28 Weeks
The glucose challenge test is typically scheduled between 24 and 28 weeks. This screens for gestational diabetes, a condition where your body can’t manage blood sugar efficiently during pregnancy. The test itself is straightforward: you drink a sugary liquid containing 50 grams of sugar, wait one hour without eating or drinking anything other than water, then have your blood drawn. A blood sugar reading below 140 mg/dL is considered normal. A result between 140 and 190 mg/dL means you’ll need a longer, three-hour follow-up test to confirm or rule out gestational diabetes. A result at or above 190 mg/dL typically indicates gestational diabetes on its own.
If your blood type is Rh-negative (something your provider will have identified early in pregnancy), you’ll receive an injection around 28 weeks to prevent your immune system from producing antibodies that could attack the baby’s red blood cells if the baby is Rh-positive. This is a routine precaution.
Nutrition in the Final Stretch
Iron needs increase significantly in the last two trimesters. Your body requires slightly more than 1,000 mg of iron across the full pregnancy, and the bulk of that demand is concentrated from now until delivery. Iron supports the rapid expansion of your blood volume and helps build the baby’s own blood supply and iron stores. Studies consistently show that women who don’t supplement with iron see measurably lower hemoglobin levels after 24 to 28 weeks compared to those who do. If you haven’t already been taking an iron supplement, this is worth discussing at your next appointment.
Calcium and protein remain important throughout the third trimester as the baby’s bones harden and body mass increases rapidly. The baby will roughly triple in weight between now and birth, gaining about 4 to 5 more pounds over the remaining 12 weeks. Your caloric needs increase modestly in the third trimester, by roughly 300 to 450 extra calories per day, but the quality of those calories matters more than the quantity.
What to Expect at Prenatal Visits
Starting around 28 weeks, most providers shift from monthly to biweekly appointments. These visits typically include a blood pressure check, a urine test, a measurement of your uterine growth (fundal height), and a check on the baby’s heart rate. Your provider may also ask about fetal movement patterns, swelling in your hands or face, and any headaches or vision changes, all of which can signal complications like preeclampsia.
This is also the stage when many providers recommend finalizing a birth plan, registering at your delivery hospital, and taking a childbirth preparation class if you haven’t already. The weeks between 28 and 36 tend to pass faster than people expect, and having logistics sorted early reduces stress as your due date approaches.