12 weeks pregnant
At 12 weeks you are in the first trimester, and your baby measures about 5.4 cm from crown to rump and weighs about 14 g, roughly the length of a lime. This is the usual week for the 12-week scan and combined screening, and the risk of miscarriage falls sharply from here, which is why many people share the news around now.
Averages from standard growth tables; your scan gives your baby's own numbers.
Your baby at 12 weeks
Reflexes are developing and the kidneys make urine. Now called a fetus: the tail has gone, fingers and toes are forming and the head is about half the total length.
How you might feel
Energy often starts to return, nausea eases for most people and the uterus can now be felt just above the pubic bone.
The risk of miscarriage falls sharply; many people share the news around now.
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
Dating ultrasound
Confirms how many weeks, the heartbeat and whether there is more than one baby.
NIPT blood test (optional, private cost)
A blood test from 10 weeks that screens the baby’s DNA for Down syndrome (trisomy 21), trisomy 18 and 13, and can tell the sex.
12-week scan and combined first-trimester screening
Nuchal translucency ultrasound between 11+0 and 13+6 weeks, with a blood test (PAPP-A and free β-hCG) usually drawn from 10 weeks.
Hospital booking-in visit
Usually at 12–16 weeks, about an hour with a midwife.
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.
Coming up: 16-week antenatal visit
Review of the first-trimester results, blood pressure, the baby’s heartbeat and a referral for the morphology scan.
Checklist for the week
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Questions about 12 weeks
How many months is 12 weeks pregnant?
About three months, the end of the first trimester in a few weeks.
What trimester is 12 weeks?
Week 12 is in the first 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.
When is it safe to announce a pregnancy?
There is no fixed rule. The chance of miscarriage drops markedly after a normal 12-week scan, which is why many people wait until then, but telling people earlier is a personal choice.
Written by the Hello Bub team; medical schedule follows the Australian Pregnancy Care Guidelines; last reviewed 3 November 2026.