17 weeks pregnant
At 17 weeks you are in the second trimester, and your baby measures about 13 cm from crown to rump and weighs about 140 g, roughly the length of a pear. Book the morphology scan now if it is not already booked, since public hospital imaging slots for 18 to 20 weeks fill quickly.
Weighs about 140 g, like a cricket ball. Averages from standard growth tables; your scan gives your baby's own numbers.
Your baby at 17 weeks
Fat starts to form under the skin; the umbilical cord thickens. The body is catching up with the head, the face looks human and movements are becoming coordinated.
How you might feel
A bigger appetite, vivid dreams and occasional dizziness when standing quickly are common, and the bump is usually visible by now.
Book the morphology scan for 18–20 weeks if it is not booked.
Call your maternity unit or GP today for bleeding, severe pain, or if you cannot keep fluids down. 13 HEALTH (13 43 25 84) in Queensland; 000 in an emergency.
What's due this week in Australia
Tell your employer (when you are ready)
There is no legal deadline to tell your employer, but protections start once they know: transfer to a safe job, no-safe-job leave and special maternity leave.
16-week antenatal visit
Review of the first-trimester results, blood pressure, the baby’s heartbeat and a referral for the morphology scan.
Coming up: Morphology (anatomy) ultrasound
A detailed 30–60 minute scan of the baby’s organs, spine, heart and limbs, the placenta position and the cervix.
Coming up: Whooping cough (pertussis) vaccine
Free under the National Immunisation Program in every pregnancy.
Checklist for the week
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Questions about 17 weeks
How many months is 17 weeks pregnant?
About four months.
What trimester is 17 weeks?
Week 17 is in the second trimester. In the Australian guidelines Hello Bub follows, the first trimester runs to 13 weeks, the second from 14 to 27 and the third from 28 weeks.
Do I need to book the morphology scan myself?
In most public hospitals the referral is written at your booking visit and you phone to book. Ask at your 16-week visit if nothing has been arranged, because the scan is best done between 18 and 20 weeks.
Written by the Hello Bub team; medical schedule follows the Australian Pregnancy Care Guidelines; last reviewed 3 November 2026.