42 weeks pregnant

How big is your baby at 42 weeks?

Much the same as last week. The NHS week-by-week guide stops at week 41 and its page covers "41 weeks or more", so 42 weeks shares the same figures: the average baby is around 3 to 4 kg (6 lb 10 oz to 8 lb 13 oz), described as a pumpkin or a watermelon, with the fast period of growth over.

Expect red, dry, peeling skin at birth. The NHS explains it as vernix — the greasy layer that stops skin drying out in amniotic fluid — having been lost. Do not moisturise it. The red layer peels off within days and reveals perfect skin underneath.

What's developing this week

Nothing new is being built. What is being watched instead is the placenta and the fluid around your baby, which is why any monitoring offered from 42 weeks looks at exactly those two things.

What you might feel

Frustration, exhaustion, and the particular strain of being the last person in every group chat still pregnant. Physically nothing has changed from last week: Braxton Hicks, pressure, backache, broken sleep, heartburn, swollen feet.

What has changed is the weight of the advice. Everything below is about being watched carefully rather than waiting quietly.

Movements do not slow down at the end

At 42 weeks this is the single most useful thing you can do, and the one thing no amount of monitoring replaces between appointments. Call your midwife or maternity unit immediately if your baby is moving less than usual, if you cannot feel them moving, or if their usual pattern has changed — do not wait until the next day, do not wait for your next appointment, and call even in the middle of the night. Those are the NHS's own words, and maternity triage is staffed 24 hours a day for exactly this call.

Babies do not move less at the end because they have run out of room. The RCOG says movements tend to increase until about 32 weeks then stay roughly the same, and that you should feel your baby move right up to and during labour. Nor do you need to count: the NHS says "you do not need to count the number of kicks or movements you feel each day", and RCOG Green-top Guideline No. 57, second edition, reviewed 29 April 2026, found insufficient evidence to recommend counting using specified numbers. What matters is a change from your baby's own pattern.

Tommy's reports that 55% of women who had a stillbirth had noticed their baby's movements slow down or stop and had not reported it. Our movements counter records what normal looks like for your baby, but no number on it means everything is fine — and a home Doppler is worse: the NHS says hearing a heartbeat does not mean your baby is well.

Is 42 weeks pregnant 9 months or 10 months?

You are off the end of the map. The standard mapping finishes at month 9, weeks 36 to 40. In calendar terms you are into a tenth month; on every chart you are still in the ninth. Neither answer is useful.

There is no official weeks-to-months map, and a calendar month averages 4.3 weeks rather than 4, so 40 weeks is a little over nine months. The usual 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 counts in weeks and days. Our weeks to months converter shows both mappings.

What's happening at your appointments around now

The NHS routine schedule ends at the 41-week appointment, so from here your care is individual rather than scheduled. In practice you should already be in an active conversation with your midwife or obstetrician about how this pregnancy ends, and you should have a plan with dates in it.

NICE asks that women who choose to wait for spontaneous labour are given the chance to discuss that decision again at every subsequent review, and that they contact their midwife or maternity unit if they change their mind before the next appointment — or as soon as possible if they have concerns about their baby, "for example reduced or altered fetal movements".

42 weeks is post-term

This is the point where the labels change. On the ACOG designations, post-term begins at 42+0 weeks and beyond; 41+0 to 41+6 was late term. It is a real threshold rather than a pessimistic one, and it is why the offers change this week.

How unusual is it? NICE's figures, from NHS maternity data, show 0.9% of spontaneous labours start at 42+0 weeks or later — 99% have started before it. NICE asks clinicians to explain that labour usually starts naturally before 42+0 weeks, based on the gestational age from your dating scan. That last clause carries weight: if your dates were set by your last period rather than corrected by a scan, some of the gap may be arithmetic rather than biology, and it is a fair question to ask.

ACOG lists a pregnancy lasting more than 41 to 42 weeks among the reasons induction is recommended.

If you have decided not to be induced

This is a legitimate decision and the guidance treats it as one. The NHS: "If your pregnancy lasts longer than 42 weeks and you decide not to have your labour induced, you should be offered increased monitoring to check your baby's wellbeing."

NICE sets out what that discussion should contain, and it is unusually honest for a clinical guideline. Monitoring might consist of twice-weekly cardiotocography and ultrasound estimation of maximum amniotic pool depth. You should be told that it "only gives a snapshot of the current situation" and cannot reliably predict any change after it ends, and that adverse effects on the baby, including stillbirth, "cannot be predicted reliably or prevented even with monitoring".

That is not an argument against declining induction. It is the honest limit of what watching can do, and it is why the movements section above matters most: between appointments, you are the monitoring.

Your decision must be recorded and you can change your mind at any point. If you would rather proceed, induction is usually a membrane sweep, then hormones as a pessary, gel or tablet, or a balloon catheter, then breaking your waters and a hormone drip if needed. The NHS notes an induced labour is usually more painful than one that starts on its own — while your pain relief options are not restricted by it. Our birth plan generator has an induction path, because a plan covering only spontaneous labour is not much use this week.

When to call your midwife or doctor

These do not wait until morning.

Emergency now: 999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, 111 in New Zealand

• You think your baby is coming now and you have a strong urge to push
• You have a seizure, or you collapse

Call your midwife or maternity unit immediately, whatever the hour

• Your baby is moving less than usual, or the pattern has changed
• Your waters break — and again if the fluid is smelly, green or bloodstained
• Any vaginal bleeding
• Any contraction lasting longer than 2 minutes, or 6 or more contractions in every 10 minutes
• A severe headache painkillers do not shift, blurred vision or flashing lights, pain just below the ribs, sudden swelling of your face, hands or feet, vomiting or feeling very unwell — the NHS pre-eclampsia symptoms
• Severe itching at night, a temperature above 37.5C with no cold or flu symptoms, or persistent stomach pain
• You are waiting rather than being induced and anything at all has changed — NICE asks you to ring as soon as possible with any concern about your baby, naming reduced or altered movements specifically
• You feel that something is wrong, without being able to say what

You are past the point where anyone will think you are fussing. Ring.