28 weeks pregnant

Your baby at 28 weeks

Week 28 is where ACOG draws the line between the second and third trimesters. Your baby is compared to an eggplant and measures about 37.6 cm crown to heel. Since week 21 the guide has used crown-to-heel length, so this figure is a head-to-toe measurement and not the shorter sitting height you see on early scans.

ACOG's guide groups weeks 25 to 28 together. The lungs have their full structure but cannot yet work on their own outside the womb, and they have begun to make surfactant, a substance that helps the air sacs stay open when a baby breathes. Loud sounds can make your baby startle and pull in the arms and legs. The eyelids can open and close, the nervous system keeps developing, and as more fat is added the skin starts to look smoother and less wrinkled.

Weight is where growth speeds up. The WHO charts put the middle estimated weight at 1,189 g, with 8 in 10 babies between 1,026 g and 1,368 g, and the middle head circumference at 264 mm. These are estimates from scan measurements of the head, abdomen and thigh bone rather than anything weighed. A single position on the chart is not a verdict on its own; the trend between scans is what your team follows.

What is special about week 28 is the sense of a new phase of care. Visits begin to turn from "how is the baby developing" to "how will the birth go", and a number of checks are bunched around this week. Many of them are listed in the table of tests on this page.

Your body at 28 weeks

Everyday tasks like bending, getting out of a low chair and turning in bed may take more thought now, and many people find their balance feels different as the bump grows.

The NHS describes the 28-week appointment in detail. You get information on labor and birth, including newborn screening. Your blood pressure and urine are checked, your bump is measured, and you have a blood test that looks at your health, iron levels and blood group. If your blood group means your baby could be at risk of rhesus disease, an injection to protect against it is offered at this visit. The midwife will also talk about your baby's movements and ask how you are feeling in yourself, including your mental health.

This is also the window for the whooping cough (Tdap) vaccine. The CDC recommends it during weeks 27 to 36 of every pregnancy; the NHS offers it from 16 weeks and advises having it before 32 weeks. Check whether you have had it. Keep up gentle exercise too. The NHS suggests about 150 minutes of moderate activity a week and advises against anything that has you flat on your back for more than a few minutes in later pregnancy.

Common symptoms around 28 weeks

• Tiredness returns. The NHS says later-pregnancy tiredness often comes from carrying extra weight, and frequent trips to the toilet at night break up sleep. A relaxing routine before bed, no caffeine in the evening and pillows under the bump and between the knees can help.
• Puffy ankles and fingers. The NHS says swelling comes from your body holding more water and from the womb pressing on leg veins. It tends to build up as the day goes on. Put your feet up, avoid standing for long and wear comfortable shoes.
• Aching back. The ligaments that soften for labor keep straining your lower back. Flat shoes, bending your knees to lift and a supportive pillow in bed are NHS suggestions.
• Tightenings. You may feel your belly go firm for a moment now and then. ACOG lists regular or frequent tightening, often painless, among the signs of preterm labor, so treat a regular pattern as a reason to call rather than something to wait out.

Tips for this week

• Sleep on your side. The NHS advises going to sleep on your left or right side from now on, and rolling over if you wake up on your back.
• Put your questions together. Use the 28-week appointment to ask about the birth plan, pain relief, and how to recognize labor.
• Check your vaccines. Ask whether you have had the whooping cough vaccine; the CDC window is 27 to 36 weeks and the NHS one ends at 32.
• Ask about your blood group. If you are rhesus negative, ask when the protective injection is planned.
• Start a hospital shortlist. Look at the maternity unit's tour dates, parking and what to pack, and ask your birth partner to do the same.

When to call your doctor or midwife

These are reasons to call now, not to wait for your next appointment. If you cannot reach your maternity unit or clinic, call your local emergency number.

• Call now if you have any vaginal bleeding. Call your emergency number if it is heavy, soaks a pad quickly, or comes with severe belly pain, shoulder pain or feeling faint.
• Call now if your baby moves less than usual, you cannot feel any movement, or the pattern changes: ring your midwife or maternity unit. The NHS says to call straight away, even at night, and the RCOG says never to go to sleep ignoring a change. Rather than counting kicks to a target, learn your baby's own pattern, unless your care provider has asked you to keep a count; then follow their advice.
• Call now if you notice mild cramps, a constant dull backache, pelvic pressure, more discharge or discharge that turns watery or bloody, regular tightenings, or a gush or trickle of fluid. ACOG lists these as signs of preterm labor, which is labor before 37 weeks.
• Call now if you have a severe headache, blurred vision or flashing lights, pain under your ribs, vomiting, or sudden swelling of your face, hands or feet. The NHS says pre-eclampsia is most likely from 20 weeks and these signs need to be checked immediately.
• Call now if peeing becomes painful or burns, especially with a fever, or if back pain comes with bleeding.