17 weeks pregnant

How big is your baby at 17 weeks?

About the size of a pomegranate — around 12 cm (4.7 in) long head to bottom, according to the NHS, weighing roughly 179 g (6.3 oz).

Your placenta is growing too. By term it will weigh around 500 g, a packet of pasta — and it is still heavier than the baby it feeds.

A note on the numbers: up to week 19 the NHS measures crown to rump — head to bottom, because the legs are curled. At week 20 it switches to head to heel, which is why the length appears to leap 10 cm in a week. Weights here are the median from the WHO fetal growth charts, which begin at 14 weeks; half of babies weigh more, half less.

What's developing this week

Your baby can now move their eyes, though the lids stay shut for weeks yet, react to loud noises, and open and close their mouth.

The fingernails are growing, and with them the ridges that make fingerprints. The NHS points out these are unique — even identical twins have different fingerprints, because the pattern is shaped by the physical environment in the womb rather than written in the genes.

ACOG describes weeks 17 to 20 as when the part of the brain controlling movement becomes fully formed, the digestive system starts working, and a soft downy hair called lanugo begins to cover the body.

What you might feel

Your waist starts to vanish as the womb moves up and out of the pelvis, which is what makes most people look obviously pregnant rather than just changed.

Stretch marks

Depending on your skin colour you may notice pink, red, purple or brown streaks over your stomach and breasts. The NHS says they affect up to 8 in 10 women, are caused by hormones and stretching skin, and usually fade to silver after birth. No cream has been shown to prevent them.

The bit nobody puts on a list

The NHS states on this week's page that around 1 in 5 women feel stressed or anxious during pregnancy. One in five is not a rare complication. If you feel sad or worried, talk to your doctor or midwife — you need not be in crisis to be referred.

Is 17 weeks pregnant 3 months or 4 months?

Week 17 is the last week of month 4. Month 5 starts at week 18.

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

Usually nothing at 17 weeks. In the UK the anomaly scan is next, between 18 and 21 weeks, and may already be in the diary. If it is not booked, chase it now: NICE specifies 18 weeks and 0 days to 20 weeks and 6 days, and booking arrangements differ by area — some get a letter, some book by phone or app, some are handed a form and expected to act on it. In the US the standard ultrasound is done at 18 to 22 weeks.

When will you feel your baby move?

The question of the second trimester, and the honest answer is a range, not a date. The NHS says movement is first felt between 16 and 24 weeks, and with a first baby often not until after 20; its week-by-week guide gives a narrower 18 to 24. Tommy's says 16 to 24 weeks, later than 20 in a first pregnancy and possibly as early as 16 if you have been pregnant before. The spread is real.

Early movements feel like bubbling, fluttering or rolling — almost everyone mistakes the first few for wind. Babies move more after meals and when you are lying still, and an anterior placenta cushions the kicks, so you may feel less and later.

There is no deadline inside that range, and nothing is wrong if a friend at the same gestation felt something weeks ago. The one checkpoint: if you have felt nothing at all by 24 weeks, tell your midwife. Once movements do start, do not count kicks — both the NHS and Tommy's say there is no set number. Learn your baby's pattern, and if it reduces, weakens or changes, ring your maternity unit immediately.

Is it safe to fly at 17 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.

Seventeen weeks is close to the practical sweet spot: sickness gone, energy back, bump not yet in the way. The only date to work around is the anomaly scan.

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
• If movements have started and they slow, weaken or change, call immediately — not in the morning. Having felt nothing yet at 17 weeks is ordinary.

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