23 weeks pregnant
At 23 weeks you are in the second trimester, and your baby measures about 29 cm from head to heel and weighs about 500 g, roughly the length of a corn cob with its husk. Antenatal classes and childcare waitlists are the admin for these weeks, and the glucose tolerance test window opens next week.
Weighs about 500 g, like a packet of pasta. Averages from standard growth tables; your scan gives your baby's own numbers.
Your baby at 23 weeks
The lungs start producing surfactant; hearing is well developed. Curled in the fetal position and filling out with fat; the eyes open from about week 26.
How you might feel
Braxton Hicks tightenings may begin, and backache, heartburn and pelvic pressure are common as the baby grows.
Braxton Hicks tightenings may begin.
Call the maternity unit today for bleeding, fluid loss, a severe headache or vision changes. 13 HEALTH (13 43 25 84) in Queensland; 000 in an emergency.
What's due this week in Australia
Whooping cough (pertussis) vaccine
Free under the National Immunisation Program in every pregnancy.
Book antenatal classes and a hospital tour
Public hospitals run free or low-cost childbirth, breastfeeding and early-parenting classes, in person or online.
Put your name on childcare waitlists
If you plan to use childcare in the first year, many centres have waitlists of 6–12 months.
Coming up: 24–25-week antenatal visit (first pregnancy)
Blood pressure, fundal height, the baby’s movements, and the request forms for the glucose test and 28-week bloods.
Coming up: Gestational diabetes test (OGTT)
A fasting 75 g oral glucose tolerance test at a pathology collection centre: a fasting blood sample, the drink, then samples at 1 and 2 hours.
Checklist for the week
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Questions about 23 weeks
How many months is 23 weeks pregnant?
About five and a half months.
What trimester is 23 weeks?
Week 23 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.
What are Braxton Hicks contractions?
Irregular, usually painless tightenings of the uterus that come and go without a pattern. Regular, painful contractions before 37 weeks, or any bleeding or fluid loss, need a call to the maternity unit.
Written by the Hello Bub team; medical schedule follows the Australian Pregnancy Care Guidelines; last reviewed 3 November 2026.