Welcome to the third trimester. Week 28 is a significant milestone — the final chapter of pregnancy has begun. Your baby now weighs a full kilogram, and the weeks ahead will be defined by rapid weight gain, continued brain development, and increasing preparation for life outside the womb.
The third trimester typically brings a mix of anticipation and intensified physical demands. Your body is doing extraordinary work, and your prenatal appointments will now become more frequent. For uncomplicated pregnancies, ACOG generally recommends appointments every two to four weeks starting around 28 weeks.
Track your progress with our Due Date Calculator.
Key Takeaways
- Welcome to the third trimester: your baby now weighs a full kilogram and measures about 37.6 cm
- Prenatal appointments increase in frequency from 28 weeks — every 2–4 weeks per ACOG guidelines
- If you are Rh-negative, the Rhogam injection is given at 28 weeks to prevent Rh sensitization
- Start formal kick counting from this week: 10 movements in under 2 hours is the standard benchmark
- The immune system is receiving an accelerating transfer of maternal antibodies through the placenta
Your Baby This Week
Size: Eggplant — about 37.6 cm (head to toe)
Weight: About 1 kilogram
The one-kilogram mark is a genuine milestone. Here's what's developing:
- The third trimester begins. Weeks 28 to 40 are defined by rapid growth, fat accumulation, and final organ maturation. Your baby will roughly triple in weight between now and birth.
- Brain development is accelerating. The cerebral cortex is developing complex folds and grooves, and the neural networks connecting different brain regions are becoming more elaborate and efficient.
- The eyes can respond to light. Pupils dilate and contract in response to light entering through the uterine wall. This reflex, which will be tested at birth, is now functional.
- REM sleep cycles are well established. Your baby spends most of their time asleep, cycling between REM and non-REM sleep states. During REM, the eyes move rapidly under closed lids — just as in adults.
- Bone marrow has taken over blood cell production. The liver and spleen, which handled this function earlier, have largely handed it off to the marrow.
- The immune system is receiving an influx of antibodies. Transfer of maternal IgG antibodies through the placenta accelerates in the third trimester, giving your newborn a temporary immune foundation at birth.
Your Body This Week
The third trimester brings a new set of physical experiences, many of which are intensified versions of what you've been feeling:
- More frequent prenatal appointments. Starting around 28 weeks, most providers schedule appointments every two to four weeks, transitioning to weekly visits in the final month. These visits include blood pressure monitoring, fundal height measurement, fetal heartbeat, and discussion of any concerns.
- Glucose test results. If you had an elevated one-hour test and then a three-hour diagnostic test, your results should be back by now. If you've been diagnosed with gestational diabetes, your provider will outline a management plan — typically dietary changes first, with medication if needed.
- Rh factor injection. If you have Rh-negative blood type, your provider will recommend an Rh immunoglobulin (Rhogam) injection at 28 weeks to prevent Rh sensitization, which can cause complications in this or future pregnancies.
- Back pain intensifies. The weight of the growing uterus increases the strain on the lumbar spine. Supportive footwear, a pregnancy support belt, and regular gentle exercise all help.
- Trouble sleeping. Many people find sleep becomes increasingly difficult in the third trimester. Frequent urination, discomfort, heartburn, and leg cramps all contribute. Prioritizing rest — even if it's broken — is important.
- Shortness of breath. The uterus is now pressing firmly against the diaphragm, reducing lung capacity. Some breathlessness during exertion is normal. Sudden or severe shortness of breath at rest is not.
Tips for Week 28
1. Start formal kick counting. Many providers recommend daily fetal movement monitoring from 28 weeks. A common method: count 10 kicks, rolls, or flutters. It should take less than 2 hours; most babies achieve 10 movements within 30 minutes of starting. Do this at a consistent time each day, ideally after a meal when the baby is typically more active.
2. Get the Rhogam shot if needed. If you're Rh-negative and haven't already had the injection, mention it to your provider this week. This is time-sensitive.
3. Pack your hospital bag in stages. You don't need to have it fully packed right now, but starting to gather items prevents a last-minute scramble. Our Hospital Bag Checklist covers everything you'll need.
4. Discuss Group B Strep testing. GBS screening is typically done between 35 and 37 weeks. Understanding what it is, what a positive result means, and what happens during labor if you test positive removes anxiety later.
5. Evaluate your mental health. The transition to the third trimester is a common trigger for increased anxiety. Perinatal anxiety and depression are both common and treatable. If you're struggling, talk to your provider — there are safe, effective options.
When to Call Your Doctor
- Decreased fetal movement. You've started kick counting — if you can't count 10 movements in two hours, call your provider.
- Contractions before 37 weeks: regular, rhythmic contractions — with or without pain — need evaluation
- Signs of preeclampsia: severe headache, visual changes (blurred vision, floaters, light sensitivity), sudden significant swelling in the face or hands, upper right abdominal pain. Preeclampsia becomes more common in the third trimester.
- Vaginal bleeding beyond light spotting — needs same-day evaluation
- Sudden severe shortness of breath at rest — can indicate pulmonary embolism, which is rare but more common in pregnancy
Frequently Asked Questions
How big is my baby at 28 weeks pregnant?
At 28 weeks, your baby measures about 37.6 cm (14.8 inches) from head to toe and weighs approximately 1 kilogram (2.2 lbs) — roughly the size of an eggplant. This is a significant milestone: from here, your baby will roughly triple in weight by the time of birth.
What is kick counting and how do I do it?
Kick counting is a method of daily fetal movement monitoring recommended from 28 weeks. Count the time it takes to feel 10 kicks, rolls, or flutters from your baby. According to ACOG, most babies achieve 10 movements within 30 minutes when active, and it should take no longer than 2 hours. Do your count at a consistent time each day — ideally after a meal when your baby is typically more active. If you can't reach 10 movements in 2 hours, contact your provider.
What is the Rhogam injection and do I need it?
Rhogam (Rh immunoglobulin) is an injection given at 28 weeks to people with Rh-negative blood type. If you're Rh-negative and your baby inherits Rh-positive blood, your body could develop antibodies that attack the baby's red blood cells — a condition called Rh sensitization. The injection prevents this from occurring and is time-sensitive. A second dose may be given after delivery if the baby is confirmed Rh-positive.
How often will I see my provider in the third trimester?
From around 28 weeks, ACOG generally recommends prenatal appointments every 2–4 weeks for uncomplicated pregnancies, transitioning to weekly visits in the final month (from about 36 weeks). These visits include blood pressure monitoring, fundal height measurement, fetal heart rate check, urine analysis, and any relevant discussions about birth preparation.
Is shortness of breath normal at 28 weeks?
Mild shortness of breath during exertion is common as the uterus pushes upward against the diaphragm, reducing lung capacity. This typically worsens through the third trimester until the baby drops (lightening) closer to delivery. Practicing good posture — sitting and standing tall — helps create more room. Sudden or severe shortness of breath at rest, or breathlessness accompanied by chest pain or palpitations, should be evaluated promptly as it can indicate a pulmonary embolism, which is more common in pregnancy.
Related Tools & Articles
- Due Date Calculator — Calculate your estimated due date
- Hospital Bag Checklist — start packing
- Pregnancy Week-by-Week Overview — full timeline
- Milestone Tracker — track your baby's development
- Contraction Timer — get familiar with it before you need it