At 23 weeks pregnant, your baby is roughly the size of a large mango or a small grapefruit — about 28 to 29 cm from head to heel and around 500 g. The most notable change this week is inside the lungs, where tiny blood vessels are forming in preparation for breathing air after birth.
How big is your baby at 23 weeks?
At 23 weeks, most babies measure around 28 to 29 cm from the crown of the head to the heel and weigh in the region of 500 g. Those figures are averages, so treat them as a middle point rather than a target — perfectly healthy babies sit above and below them every day.
- Length: about 28 to 29 cm, roughly 11 to 11.5 inches, head to heel
- Weight: about 500 g, a little over 1 lb
- Everyday comparison: a large mango or a grapefruit — and a shade shorter than a 30 cm (12 inch) ruler
A scan weight is an estimate with a built-in margin of error in both directions, so the pattern over time matters far more than any single number on any single day.
Why length figures jump between charts. Up to about 14 weeks, babies are measured crown to rump — head to bottom — because the legs are curled up too tightly to measure. From around 20 weeks, charts switch to crown to heel. That is why a length can appear to almost double between two sources. At 23 weeks you are well past the switch, so check that any chart you compare yourself with uses head to heel.
How many months is 23 weeks, and how are the weeks counted?
Pregnancy is dated from the first day of your last menstrual period, not from the day you conceived. That is the gestational age your midwife, doctor and every scan report use, and it puts about two weeks on the clock before conception happened. So at 23 weeks pregnant, your baby has been growing for roughly 21 weeks.
In months, week 23 puts you at the start of your sixth month, still comfortably in the second trimester. Since four weeks is not a calendar month, some charts place week 23 at the end of month five instead — both describe the same point. To see how this week fits the bigger picture, our week-by-week pregnancy guide walks through every stage in order.
What your baby is doing this week
- Laying down fat. It has started, but there is little of it yet, so the skin is still thin, wrinkled and reddish — the blood vessels underneath show straight through.
- Building the blood supply to the lungs. Blood vessels are developing through the lung tissue, groundwork for the oxygen exchange your baby will need after birth. It is one of the most important things happening this month.
- Listening. Hearing is well established, so a sudden loud noise can produce a startle. Your voice and your heartbeat are the constant background of your baby's world.
- Starting rapid eye movements. The eyes have begun the quick movements associated with sleep cycles.
- Sensing position and movement. The inner ear is maturing, so your baby is beginning to register being upright, tilted or rocked.
Every baby runs to its own timetable, and any of this can arrive a week or two either side. None of it needs managing.
What you may be feeling at 23 weeks
Movement is usually the headline. The kicks and rolls are often strong enough now for a partner to feel with a hand on your bump, and you may catch a ripple travelling across the surface. Some babies are busiest late at night, some after you eat, some to no pattern you could describe.
You do not need to formally count kicks at this stage — structured movement counting is something care teams normally introduce much later in pregnancy. But once movements are well established, any reduction or change is worth an immediate call, at any hour. Do not wait until morning, do not try cold drinks or sugary snacks to provoke a kick first, and do not worry about being a nuisance. Maternity units expect these calls and would far rather hear from you.
Braxton Hicks tightenings often show up around now: the bump goes hard for perhaps 30 seconds, then softens. They are irregular, usually painless, and they ease off when you change position, rest or have a drink of water. They are practice, not progress.
Other things that are common right now:
- Swollen feet and ankles, worst by the end of the day
- Backache as your centre of gravity shifts forward
- A blocked or stuffy nose, nosebleeds, or snoring you never used to do
- Heartburn and indigestion, especially lying down
- A darker line down the middle of your abdomen, the linea nigra
- Stretch marks on the bump, breasts, hips or thighs
- Tingling, numbness or aching in the hands and wrists from carpal tunnel pressure
You might have most of that list or almost none of it, and both are ordinary. Comfort measures are worth trying: feet up when you can, supportive shoes, an extra pillow, smaller meals earlier in the evening. Anything you swallow or rub on, including herbal teas, supplements and anything off a pharmacy shelf, needs clearing with your doctor, midwife or pharmacist first. Natural does not mean safe in pregnancy.
What to do this week
Screening for gestational diabetes is usually offered shortly after now, between about 24 and 28 weeks. Who is offered it and how it is run differs between countries and hospitals. Antenatal schedules genuinely vary that way, so follow your own midwife, doctor and national programme rather than a general page like this one.
Worth doing this week: save the out-of-hours number for your maternity unit or midwife in your phone, and tell your partner or a friend where it is. The point of having it saved is that you never have to hunt for it while you are frightened at 2am.
This is also the point where it genuinely matters to recognise the signs of preterm labour. Ring your midwife or maternity unit — do not wait and see — if you notice:
- Tightenings that come regularly and keep coming, whatever you do
- Low backache that comes and goes in waves
- Cramping that feels like a period
- A gush or a slow trickle of fluid
- Any bleeding at all
- A change in your usual discharge, in amount, colour or texture
Most of the time there is a simpler explanation, and being checked over and sent home reassured is a good outcome, not a wasted trip. It is always right to call rather than wait and see.
You may also meet the word "viability" around this week, and it can land heavily if you find it alone at night. Briefly and honestly: around 23 to 24 weeks is widely described as the edge at which specialist neonatal care may be able to support a baby born extremely early. Outcomes vary enormously by country, by hospital and by individual circumstances, and nothing on a general website can tell you anything meaningful about your own pregnancy. If it is on your mind — especially if you have had a loss, or have been told you are at higher risk — take it to your own midwife or doctor.
When to call your doctor or midwife straight away
Do not sit on any of these, whatever the time of day:
- Any bleeding, however light
- Severe or persistent abdominal pain
- A gush or trickle of fluid, or feeling suddenly wet
- Fever, or feeling generally unwell
- A severe headache, changes to your vision such as flashing or blurring, or sudden swelling of your face, hands or feet
- Pain or burning when you pass urine
- Reduced or changed movements, now that movements are established
- Any sudden severe symptom, or a strong feeling that something is not right
That last one counts. If your instinct says something has changed, make the call and let someone check.
Follow week 23 in your pocket
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