Pregnancy Week 28: Welcome to Third Trimester

Week 28 has a psychological weight beyond the calendar. You're officially in the last third of your pregnancy — 12 weeks or so from meeting your baby. Every stretch, twinge and kick from now on feels a bit more like preparation than possibility. If you've been coasting through the second trimester, this week is often when the reality of "we're doing this" starts to settle back in.

This guide walks through what's happening at 28 weeks pregnant, the tests you'll likely have this month (glucose tolerance, Rh antibody), the symptoms most people notice, safe nutrition and movement, kick counts, and the signs that mean it's time to call your clinician.

This article is educational, not medical advice. Pregnancy is deeply individual, and your obstetrician or midwife is the person who knows your history. We're the team behind Vyve, the private AI pregnancy and cycle tracker, and Vyve is a tracking tool — not a diagnostic one.

What's happening this week

You've entered the third trimester. Prenatal visits typically become more frequent from around now — every two weeks until 36, then weekly. There's a shift in focus, too: from monitoring baby's development to preparing for birth. Birth plans, hospital bag conversations, and childbirth education all get real from here.

If you'd like to see what's ahead, take a look at week 29 and week 30, when baby's regulation of body temperature begins to develop.

Baby's size and development at week 28

At 28 weeks pregnant, your baby is about the size of an eggplant or a large aubergine — roughly 37 centimeters (14.6 inches) from head to heel, weighing around 1 kilogram (2.2 pounds). From here on, weight measurements are typically head-to-heel rather than crown-to-rump.

Here's what's happening this week:

• Eyes are opening. Eyelids that were fused since early pregnancy now open and close. Baby can perceive light and dark.
• Brain is rapidly developing. Neural connections are forming at breathtaking speed; grooves and folds appear on the brain surface.
• REM sleep begins. Baby now has sleep-wake cycles, including dream sleep.
• Fat is accumulating, making baby's skin less wrinkly and helping with temperature regulation after birth.
• Lungs continue maturing. Baby is practicing breathing movements, drawing amniotic fluid in and out.
• Bone marrow now produces red blood cells (previously the liver and spleen did this).
• Baby can hear well — your voice, familiar music, and household sounds.
• Position shifts. Baby may still be moving between positions, though will start settling head-down over the coming weeks.

Your symptoms and body changes

Third-trimester symptoms are showing up:

• Returning fatigue. The second-trimester energy tapers as your body carries more weight and sleep gets harder.
• Heartburn. Progesterone relaxes the valve at the top of the stomach; the growing uterus pushes upward.
• Braxton Hicks contractions. Irregular tightening of the uterus — practice contractions. They should be irregular and painless.
• Backache. Baby is heavier, posture is shifting, ligaments are looser.
• Leg cramps. Often at night, often calf muscles. Stretching and staying hydrated help.
• Swelling in feet, ankles and hands — some is normal. Sudden or severe swelling, especially with headache or vision changes, needs urgent evaluation for preeclampsia.
• Shortness of breath. Uterus is pressing on the diaphragm.
• Restless legs. Common in the third trimester.
• Vivid dreams. Continue in the third trimester, often more birth-related.
• Colostrum leakage. Some people notice small amounts of colostrum (yellowish early milk) leaking from their breasts.

Third-trimester tests: GTT & Rh

Glucose tolerance test (GTT). Between 24 and 28 weeks, most clinics screen for gestational diabetes. Protocols vary — a one-hour glucose challenge is common as a screen, with a longer three-hour test as confirmation if the screen is elevated. Gestational diabetes is common and manageable; it matters because uncontrolled high blood sugar affects both you and baby. If you're diagnosed, your clinician will guide you through diet changes, monitoring, and (sometimes) medication.

Rh antibody screening + anti-D. If you have Rh-negative blood and there's any chance baby is Rh-positive, you'll typically be offered an anti-D (RhoGAM) injection around 28 weeks. This prevents your body from making antibodies against baby's red blood cells, which protects future pregnancies (and this one).

Other blood work. Repeat blood counts to check for anemia (iron stores get depleted this stretch), and sometimes repeat screening for infections.

Group B strep test is usually done later — around 35 to 37 weeks — but your clinician may mention it now.

Kick counts and movement

By 28 weeks, baby's movement pattern is well-established. This is when many clinicians introduce kick counts. Protocols vary, but a common approach:

• Choose an active time of day (baby is usually more active after meals or when you're resting).
• Sit or lie comfortably.
• Count distinct movements — kicks, rolls, jabs (not hiccups).
• 10 movements within 2 hours is a common benchmark; many people notice 10 in far less time.

What matters most is knowing your baby's pattern. A noticeable decrease in movement always warrants a call to your clinician. Don't wait until the next day. Don't assume "maybe baby's just sleeping." Trust your instincts and call.

Nutrition this week

You need about 450 extra calories a day in the third trimester. Keep taking your prenatal vitamin. Priorities:

• Iron — anemia risk peaks in the third trimester.
• Calcium — baby's bones are hardening fast.
• Protein — supports rapid growth.
• DHA omega-3s — baby's brain is developing rapidly.
• Fiber and water — constipation and hemorrhoids are common.
• Small frequent meals can ease heartburn better than three large ones.

Continue to avoid raw or undercooked meat and eggs, high-mercury fish, unpasteurized dairy and juice, and alcohol.

Yoga & safe exercise

Keep moving if your clinician has cleared it, but expect to modify more. Walking, swimming, prenatal yoga, and gentle strength training remain solid. Skip anything flat on your back, avoid overheating, and take frequent breaks. If you can no longer hold a conversation while moving, dial back. Pelvic floor and hip-opening work now pays dividends during labor.

What to ask your doctor

• What are my GTT results and what do they mean for me?
• Do I need anti-D (RhoGAM) this trimester?
• How often should I be counting kicks, and when should I call?
• How's my blood pressure — should I watch for anything specific?
• When should I start childbirth classes if I haven't?
• When and how will we discuss my birth plan?
• Is baby's position what we'd expect at this stage?
• Am I anemic — do I need extra iron?

Common concerns at 28 weeks

3 tips for this week

1. Book childbirth classes if you haven't. Weeks 28–32 is a common sweet spot — early enough to absorb the material, late enough that it stays relevant.
2. Set up a kick-count habit. Same time each day, when baby is usually active. A tracker like Vyve makes it easy to log without ceremony.
3. Start the hospital bag conversation. Not fully packed yet, but list the essentials, know where things are, and give yourself weeks to think.

How Vyve helps you track your pregnancy

Vyve is a privacy-first AI pregnancy and cycle tracker built for people who don't want their body's most personal data sold to advertisers. At 28 weeks, Vyve helps you log kick counts, note new third-trimester symptoms, and prepare doctor-ready summaries for the increasingly frequent appointments.

Vyve runs its AI on your device, encrypts your data, and doesn't require an account. Your pregnancy is yours.

Frequently asked questions

How big is baby at 28 weeks pregnant?

At 28 weeks, baby is about the size of an eggplant (or a large aubergine) — roughly 37 centimeters (14.6 inches) from head to heel, and weighing around 1 kilogram (2.2 pounds). Baby is well-proportioned now and rapidly gaining fat.

What is the glucose tolerance test at 28 weeks?

The oral glucose tolerance test (OGTT) screens for gestational diabetes and is typically done between 24 and 28 weeks. You drink a sugary solution, then have your blood sugar measured after a specific interval. If results are borderline or elevated, a longer confirmatory test may follow. Managing gestational diabetes matters for both your health and baby's, and your clinician will guide you if it's flagged.

Why do I need a Rh antibody injection at 28 weeks?

If you have Rh-negative blood and there's any chance baby is Rh-positive, you'll typically be offered an anti-D (RhoGAM) injection around 28 weeks to prevent your body from making antibodies against baby's red blood cells. This protects future pregnancies as well as this one. Your clinician will explain whether it applies to you.

How often should baby move at 28 weeks?

By 28 weeks, movement patterns are usually well-established. Many clinicians ask you to notice roughly 10 movements within 2 hours during an active period, though exact "kick count" protocols vary. What matters more than a specific number is knowing baby's normal pattern. A noticeable decrease in movement always warrants a call to your clinician — don't wait.

Is baby viable at 28 weeks?

Yes — by 28 weeks, survival rates for babies born prematurely are very high with modern neonatal intensive care, though hospital NICU support would still be needed. Every extra week of pregnancy from here on out matters for baby's long-term outcomes, so full-term (37+ weeks) is still the goal. The good news is you've reached the point where prematurity, while never good, has become significantly less dangerous.

This article is educational and not medical advice. Always consult your obstetrician or midwife for personal medical guidance.