At 29 weeks, you’re solidly into the third trimester, and both your body and your baby are changing fast. Your baby weighs roughly 2.5 pounds (about 1,150 grams) and measures around 38.6 centimeters from head to heel, close to the length of a large butternut squash. From here on out, your baby’s main job is gaining weight and refining the organ systems that will support life outside the womb. For you, this week often brings a new wave of physical symptoms as the demands of a growing uterus ramp up.
What Your Baby Is Doing This Week
Your baby’s brain is developing rapidly, and the senses are coming online in remarkable ways. The eyelids, which were fused shut for months, opened a few weeks ago. By now, your baby can detect light that filters through the uterine wall. Research published in Developmental Science found that fetuses as early as 26 weeks begin tracking light stimuli with their eyes, and this ability strengthens steadily through the third trimester. Even more striking, fetuses at this stage preferentially turn their heads toward face-like patterns of light projected through the abdomen, suggesting the brain is already wired to recognize faces before birth.
Bones are hardening but the skull stays flexible, which matters for delivery later. The lungs are maturing, though they’d still need help if your baby were born now. Fat is accumulating under the skin, smoothing out the wrinkled appearance and helping regulate body temperature. You’ll likely notice stronger, more defined movements this week: actual kicks and rolls rather than the flutters of earlier months.
Common Physical Symptoms at 29 Weeks
The third trimester introduces a new set of discomforts, most of them caused by the combined effects of a larger uterus, shifting hormones, and increased blood volume. Not every person experiences all of these, but here’s what commonly shows up around this point:
- Shortness of breath. Your growing uterus pushes upward against your diaphragm, compressing the space your lungs have to expand. You may find yourself winded after climbing stairs or even talking for a while. Your body is also carrying more blood volume than usual, so your respiratory rate naturally increases.
- Heartburn and constipation. Pregnancy hormones slow down your entire digestive tract, and the uterus presses on the intestines and stomach. The combination means food moves through more slowly, stomach acid backs up more easily, and bowel movements become less predictable.
- Backaches. Hormones are loosening the ligaments in your pelvis to prepare for delivery, but that looseness can make your lower back feel unstable. At the same time, your abdominal muscles are stretching to accommodate the uterus, so your core has less support than usual.
- Frequent urination. As the baby settles deeper into your pelvis, bladder pressure increases. You may also leak urine when you laugh, sneeze, or cough.
- Heart palpitations. Brief episodes of fluttering or a pounding heartbeat are common in the third trimester. They typically happen because your expanding uterus slows blood return to the heart. These are usually harmless, but mention them at your next appointment if they’re frequent or accompanied by dizziness.
- Varicose veins and hemorrhoids. The extra blood volume circulating through your body can cause swollen veins in the legs and, less pleasantly, in the rectal area. Standing or sitting for long stretches tends to make them worse.
Braxton Hicks vs. Preterm Labor
Many people start noticing Braxton Hicks contractions around this time. These are mild tightenings across your abdomen that come and go without a pattern. They typically happen only once or twice an hour, a few times a day, and last less than a minute. They often stop if you change what you’re doing: sit down if you’ve been walking, or get up and move if you’ve been resting.
Preterm labor contractions feel different in important ways. They become regular, growing more frequent and more intense over time rather than fading away. They get longer and more painful as they progress, and they don’t respond to changes in activity. If you notice contractions that follow a pattern, come more than four times in an hour, or are accompanied by pelvic pressure, lower back pain that doesn’t let up, or any fluid leaking, contact your provider right away. At 29 weeks, early intervention can make a significant difference in outcomes.
Tracking Your Baby’s Movements
Your provider may suggest starting kick counts around this time. The idea is simple: you’re learning your baby’s normal activity pattern so you can spot changes. There are two common approaches. You can count how many movements you feel in one hour, or you can time how long it takes to feel 10 movements.
To get accurate counts, pick a time when the baby is usually active (many babies are most active in the evening). Lie on your left side or sit with your feet up, place your hands on your belly, and count kicks, rolls, and flutters. Ten movements in one hour is considered typical. Some babies hit that number in 15 minutes, others take closer to two hours, and both can be normal. What matters most is consistency. If your baby’s pattern changes noticeably, or you’re having trouble reaching 10 movements, that’s worth a call to your provider. Fewer than 10 kicks in an hour doesn’t automatically mean something is wrong, but it’s information your care team wants to know about.
Nutrition and Supplements
Your baby is building bone, producing blood cells, and laying down fat stores, all of which draw heavily on your nutrient intake. Iron needs are especially high in the third trimester because your blood volume has expanded significantly and your baby is stockpiling iron for the first months after birth. The World Health Organization recommends 30 to 60 milligrams of supplemental iron daily during pregnancy, alongside 400 micrograms of folic acid. If you’re taking a prenatal vitamin, check the label to see if it covers these amounts.
Calcium is critical now too, since your baby’s bones are hardening. If your diet doesn’t supply enough, your body will pull calcium from your own bones to meet fetal demand. Dairy, fortified plant milks, leafy greens, and canned fish with soft bones (like sardines) are all good sources. Iron absorbs better when paired with vitamin C, so having orange slices with an iron-rich meal or taking your supplement with a glass of juice can help.
Sleep and Comfort
Getting comfortable at night becomes a real challenge in the third trimester. Side sleeping is the recommended position from here on out. Lying on your back puts the full weight of the uterus on the inferior vena cava, the large vein that returns blood from your lower body to your heart. This can reduce blood flow to you and the baby, and often causes dizziness or nausea. The left side is generally preferred because it optimizes blood flow to the placenta and improves kidney function, which helps reduce swelling.
A pillow between your knees and another tucked under your belly can create a slight forward tilt that takes pressure off your hips and lower back. Some people also find a pillow behind their back helpful for keeping them from rolling over during the night. If you wake up on your back, don’t panic. Simply shift to your side. The discomfort of back sleeping usually wakes you before it becomes a problem.
Vaccines and Appointments
If you haven’t received the Tdap vaccine yet, this is the window. The CDC recommends getting it between weeks 27 and 36 of each pregnancy, with the earlier part of that range preferred. The timing is deliberate: your body produces antibodies in response to the vaccine, and those antibodies cross the placenta to protect your newborn from whooping cough during the first few months of life, before the baby can be vaccinated directly.
At this stage of pregnancy, prenatal visits typically shift to every two weeks. Your provider will check your blood pressure, measure your fundal height (the distance from your pubic bone to the top of your uterus), and listen to the baby’s heartbeat. Some practices also run a blood test around this time to screen for anemia, since iron demands peak in the third trimester. If you haven’t discussed your birth preferences or taken a childbirth class yet, this is a practical time to start, since the weeks ahead tend to move quickly.