23 weeks pregnant

How big is your baby at 23 weeks?

About the size of a large mango — around 28.9 cm (11.4 in) long head to heel, according to the NHS, weighing roughly 565 g (1 lb 4 oz).

Your baby has gained almost 100 g in a week, and is six times the weight they were at 14 weeks.

A note on the numbers: from week 20 the NHS measures head to heel, not head to bottom. That is why the length jumps from 15.3 cm at 19 weeks to 25.6 cm at 20 — no baby grew 10 cm in a week, the tape measure moved. Weights here are the WHO fetal growth chart median; half of babies weigh more, half less.

What's developing this week

Your baby's limbs are now in proportion — the long stretch of a disproportionately large head is over.

Over the next few weeks movements become visible from outside. The NHS describes it accurately: you are going to be kicked around, and you will start to see your tummy move.

Fat is forming under the skin, and hearing is established enough that familiar voices are learned months before they can be recognised out loud.

What you might feel

Your breasts may start leaking colostrum, the early milk. It predicts nothing about feeding later.

Two new complaints arrive together: rib pain, as your rib cage expands, and breathlessness, as the baby presses upward on your lungs. Both are ordinary. Sudden breathlessness, or breathlessness with chest pain or at rest, is not, and needs urgent assessment.

The NHS uses this week's page to raise mental health, pointing to Tommy's online wellbeing plan. Around 1 in 5 pregnant people experience anxiety or low mood — one of the commonest complications of pregnancy, and one of the most treatable.

Is 23 weeks pregnant 5 months or 6 months?

Week 23 is the first week of month 6. The second trimester runs to the end of week 27.

There is no official weeks-to-months map. A calendar month averages about 4.3 weeks, not 4, so 40 weeks is a little over nine months — and two apps can disagree about which month you are in. The most widely used mapping:

• Month 1 — weeks 1 to 4
• Month 2 — weeks 5 to 8
• Month 3 — weeks 9 to 13
• Month 4 — weeks 14 to 17
• Month 5 — weeks 18 to 22
• Month 6 — weeks 23 to 27
• Month 7 — weeks 28 to 31
• Month 8 — weeks 32 to 35
• Month 9 — weeks 36 to 40

Your maternity team will not use months. Everything is booked by week and day — "19 weeks and 3 days" — because a few days change what is offered. The anomaly scan window is 18+0 to 20+6 weeks, not "about five months".

What's happening at your appointments around now

In the UK the next routine appointment is 25 weeks for a first baby — blood pressure, urine, a measurement of your bump to check growth, and a discussion about movements. If you have given birth before, the next is at 28 weeks.

Week 23 is the last stop for the anomaly scan: the NHS says if you are between 18 and 23 weeks and have not had it, tell your midwife or GP. Testing for gestational diabetes, if you are at higher risk, is offered between 24 and 28 weeks.

Viability and the 24-week line

Week 23 sits directly beneath the UK's most quoted number, so it is worth saying what that number is not. The 24-week line is definitional: the NHS calls a loss before 24 weeks a miscarriage and after that a stillbirth. It governs registration, not when survival begins.

Clinical practice uses no single threshold. The BAPM framework used across the UK, updated in February 2026, states that decisions for babies born from 22+0 to 26+6 weeks should rest on that baby's individual risk profile rather than gestational age alone. Babies born at 23 weeks with favourable risk factors sit in a different category from those without, and the framework expects joint counselling by the obstetric and neonatal teams.

The numbers at 23 weeks, with denominators attached: BAPM reports around 50 per cent of babies admitted to a neonatal unit survive to discharge, and around 1 in 5 of those admitted survive without major morbidities other than chronic lung disease. Among survivors, roughly 1 in 4 has severe impairment. ACOG cites survival to discharge of 23 to 27 per cent at 23 weeks in data from the US, England and Australia, and stresses that outcomes at 23+6 may resemble those at 24 weeks far more than those at 23+0.

The figures move by country, by unit and by the day. If this is a live question for your pregnancy, ask your own team.

Is it safe to fly at 23 weeks pregnant?

Yes, in a straightforward pregnancy — and you are inside the window everyone recommends. The RCOG is unambiguous: occasional air travel is not harmful in an uncomplicated pregnancy. There is no evidence that cabin pressure or humidity harm you or the baby, and none that flying causes miscarriage, early labour or your waters to break. ACOG names 14 to 28 weeks as the best time to travel; the NHS names mid-pregnancy.

Week 23 is near the end of the comfortable stretch rather than the permitted one: the recommended period runs to 28 weeks, after which you will need a letter. If a third-trimester trip is planned, ask now.

The risk that is real: blood clots

Pregnancy raises deep vein thrombosis (DVT) risk, and that does not ease in the second trimester. ACOG puts it plainly: any travel of four hours or more doubles DVT risk, and pregnancy adds to that. Under four hours the RCOG says you are unlikely to need special measures. Over four hours:

• Loose clothing, comfortable shoes, an aisle seat, regular walks about the cabin
• In-seat exercises roughly every 30 minutes
• Water steadily; cut down on caffeine
• Graduated compression stockings — not ordinary flight socks, and sized for you by a midwife or doctor

With other clot risk factors you may be advised to have heparin injections around the flight.

Practical points

• Airline cut-offs are usually 37 weeks for one baby, 32 for twins, so nothing restricts you yet — but from 28 weeks most airlines want a letter from your midwife or doctor, which the NHS warns can cost money and take weeks.
• Check what maternity and emergency care exists at your destination, and tell your insurer you are pregnant so that cover includes pregnancy-related care.
• Some travel vaccines and anti-malarial tablets are unsuitable in pregnancy; travel to Zika areas is not recommended.

When to call your midwife or doctor

The second trimester is the quietest stretch of pregnancy for most people, which is exactly why it is worth knowing what is not ordinary. Maternity units are staffed around the clock.

Get emergency help now

Call your local emergency number (999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, 111 in New Zealand) or go to an emergency department if you have:

• Heavy vaginal bleeding, or any bleeding with severe abdominal pain
• Abdominal pain you cannot concentrate through
• Fainting or collapse, chest pain, or sudden breathlessness
• A severe headache painkillers do not touch, blurred vision or flashing lights, pain below your ribs, or sudden swelling of your face, hands or feet — the NHS lists these as pre-eclampsia symptoms, most likely from 20 weeks, needing immediate assessment

Call your midwife or maternity unit today, whatever the hour

• Any vaginal bleeding, however light
• A gush or a steady trickle of fluid from your vagina
• Regular tightenings, or persistent low backache and pelvic pressure
• Discharge that changes colour or texture, smells strongly, or brings itching or soreness
• Itching without a rash, especially at night or on your palms and soles — the NHS asks for this to be checked, because it can be intrahepatic cholestasis of pregnancy
• A temperature, feeling generally unwell, or burning when you pee
• Any reduction, weakening or change in your baby's usual pattern of movements — the NHS says call immediately, even at night, and not to use a home doppler, because hearing a heartbeat does not mean your baby is well
• If you have felt no movement at all by 24 weeks, tell your midwife

You do not need to be certain something is wrong. That is what the number is for.