5 weeks pregnant
At 5 weeks you are in the first trimester, and your baby measures about 2 mm from crown to rump, about the size of a sesame seed. Early symptoms often start this week, which makes it a good time to book the GP visit that confirms the pregnancy and starts your public hospital referral.
Averages from standard growth tables; your scan gives your baby's own numbers.
Your baby at 5 weeks
The neural tube (brain and spinal cord) is forming; the heart begins to beat around the end of this week. A disc of cells a few millimetres across, with the yolk sac that feeds it until the placenta takes over.
How you might feel
Tiredness, sore breasts, needing to wee more often and the first waves of nausea are common, and some people feel completely well.
Tiredness, sore breasts and nausea often start. Tell your GP about every medicine you take.
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
See your GP to confirm the pregnancy
Confirm with a urine or blood test, agree your dates, review any medicines and health conditions, and start (or keep taking) a pregnancy multivitamin with 400 µg folic acid and 150 µg iodine.
Coming up: Choose your public maternity care model and get booked in
All of these are free with a Medicare card.
Coming up: First antenatal visit and booking blood tests
Blood pressure, height and weight.
Checklist for the week
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Questions about 5 weeks
How many months is 5 weeks pregnant?
About one month; hospitals count in weeks from your last period rather than in months.
What trimester is 5 weeks?
Week 5 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.
Can you see anything on a scan at 5 weeks?
Usually only a small gestational sac. A heartbeat is not reliably seen until about 6 to 7 weeks, so an early scan is normally only arranged for pain or bleeding.
Written by the Hello Bub team; medical schedule follows the Australian Pregnancy Care Guidelines; last reviewed 3 November 2026.