27 weeks pregnant

How big is your baby at 27 weeks?

About the size of a head of cauliflower — around 36.6 cm (14.4 in) long head to heel, according to the NHS, weighing roughly 1,039 g (2 lb 5 oz).

Your baby crosses a kilogram this week.

A note on the numbers: from week 20 the NHS measures head to heel, not head to bottom. Weights here are the median of the WHO fetal growth charts — half of babies weigh more, half less, and a scan estimate can be out by 10 to 15 per cent either way. A number below the median is not a diagnosis.

What's developing this week

The NHS says it plainly: your baby's lungs are now capable of breathing. Not comfortably, and not without help, but the machinery works.

A few weeks ago your baby looked like a wrinkled prune. Now fat is filling out the folds of skin and every organ is maturing towards life outside. From here the job is weight and practice rather than construction.

What you might feel

Tired, and snoring. Both are on the NHS list for this week — snoring because pregnancy swells the nasal passages. Bloating and constipation are common too, as your stomach is squeezed and progesterone slows everything down. Water, high-fibre food and fresh fruit and vegetables are the NHS advice.

Sleeping position from 28 weeks

This is worth reading now rather than next week. NHS guidance is that sleeping on either side is better than sleeping on your back, because research suggests that from week 28 sleeping on your back can double the risk of stillbirth. It is also more likely to give you backache, constipation and piles.

RANZCOG gives the same advice in Australia and New Zealand: all women should be advised to sleep on their side from 28 weeks. Practically — a pillow supporting your bump, knees bent, another pillow between your legs. And do not lie awake policing yourself. The NHS says if you roll onto your back, simply roll back onto your side. What matters is the position you settle in, not every minute of the night.

There is no target number of movements: the NHS is explicit that you do not need to count kicks. What matters is your baby's usual pattern, and calling immediately if it reduces, weakens or changes. Our kick counter describes a pattern; it does not score one.

Is 27 weeks pregnant 6 months or 7 months?

Week 27 is the last week of month 6. Month 7 starts next week, and by NHS reckoning so does the third trimester.

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. 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 — "27 weeks and 3 days" — because a few days change what is offered. Note that the NHS ends the second trimester at 27 weeks and starts the third at 28, while many US sources start the third trimester at 28 weeks too but count differently at the front end. If two sources disagree about your trimester, neither is wrong; they drew the line in different places.

What's happening at your appointments around now

No routine UK appointment falls at 27 weeks, but next week is a big one, and several deadlines converge on it. Gestational diabetes testing closes at 28 weeks in the UK and the US. If you are RhD negative, anti-D prophylaxis is offered at the 28-week appointment. The RSV vaccine is offered in the UK from 28 weeks. And whooping cough vaccination, if you have not had it, should ideally be done before 32 weeks.

If you have given birth before and have not been seen since 16 weeks, week 28 is your next contact. That is a long gap by design, not by neglect — but it does mean nobody is watching between appointments except you.

Is it safe to fly at 27 weeks pregnant?

Yes, and this is the week the paperwork changes. The NHS puts it directly: this is probably the last week you can fly anywhere without a fitness-to-fly note.

Medically nothing changes on your 28th week. The RCOG position is unchanged: occasional air travel is not harmful in an uncomplicated pregnancy, and there is no evidence that flying causes miscarriage, early labour or your waters to break. What changes is what airlines ask for.

Keep two things apart. The medical position is the RCOG's: the safest time to fly is before 37 weeks with one baby and before 32 weeks with uncomplicated twins, because from those points labour becomes likely. The airline position is a commercial rule — most carriers refuse you after 37 weeks, some set an earlier limit, and from 28 weeks most want a letter from your midwife or doctor, which the NHS warns can cost money and take weeks. An airline rule is not medical advice.

The risk that is real: blood clots

ACOG puts it plainly: any travel of four hours or more — car, train, bus or plane — 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, an aisle seat, regular walks about the cabin
• In-seat exercises roughly every 30 minutes, and water steadily
• Graduated compression stockings sized for you by a midwife or doctor — ACOG warns that stockings which are too tight or worn wrongly increase the risk instead

Practical points

• If you are flying at 28 weeks or later, request the letter now. The NHS warns it can cost money and take several weeks.
• Check what maternity and neonatal care exists at your destination, and carry your maternity notes.
• Tell your insurer you are pregnant. The NHS says cover should include care in labour, premature birth and the cost of changing your return date.
• Travel to Zika areas is not recommended; some travel vaccines and anti-malarials are unsuitable.

When to call your midwife or doctor

Maternity units are staffed 24 hours a day, and away from home you can walk into any of them.

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 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, vomiting, or sudden swelling of your face, hands or feet — NHS and ACOG both list these as pre-eclampsia symptoms needing immediate assessment
• Pain, swelling or heat in one calf or thigh, which can be a DVT

Call your midwife or maternity unit today, whatever the hour

• Any reduction, weakening or change in your baby's usual pattern of movements. Call immediately, not in the morning, and do not use a home doppler — hearing a heartbeat does not mean your baby is well
• Regular tightenings, period-type pains, or backache that is not usual for you — the NHS list for possible premature labour, meaning labour before 37 weeks, which affects about 8 in every 100 babies
• A gush or a trickle of fluid, which could be your waters breaking
• Any vaginal bleeding, however light
• Itching without a rash, especially at night or on your palms and soles — it can be intrahepatic cholestasis of pregnancy
• A temperature, feeling generally unwell, or burning when you pee

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