Third trimester
27 weeks pregnant
Your baby is about the size of a cauliflower
- First trimester1st trimester weeks 1–12
- Second trimester2nd trimester weeks 13–26
- Third trimester3rd trimester weeks 27–40+
By Clever Mum Parenting · Parenting guides
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How big is the baby at 27 weeks pregnant?
At 27 weeks pregnant, your baby is about the size of a cauliflower, roughly 36.6cm and around 875g. Welcome to the third trimester. The baby now sleeps and wakes at regular intervals and may hiccup (you'll feel rhythmic little jolts). Their lungs and brain are developing fast. These are typical averages — your midwife's measurements are the ones that matter for your pregnancy.
What might you feel at 27 weeks?
Most people at 27 weeks notice some mix of the symptoms below — and plenty notice none of them. The final stretch begins. Tiredness can return, along with heartburn, swelling and trouble sleeping. You may notice colostrum (early milk) leaking from your breasts. None of this is a diagnosis; contact your midwife if something worries you.
Common symptoms this week
- Returning tiredness
- Heartburn
- Baby hiccups (rhythmic jolts)
- Colostrum leaks for some
Symptom lists are typical, never exhaustive — and having none of them is normal too.
What should you do at 27 weeks pregnant?
The useful job this week is practical, not medical. From 28 weeks you'll have more frequent antenatal appointments. Keep counting movements and report any change without delay. Pair it with the NHS week-by-week guide if you want a second description of the same stage.
Week 27 checklist
- Note the third-trimester appointment schedule — visits get more frequent from 28 weeks
- Keep up movement awareness — pattern changes always warrant a call
What antenatal care is due around 27 weeks?
These appointments, vaccines and deadlines fall around this stage. Your maternity team will confirm your own dates.
- Whooping cough vaccine (from 16 weeks). Offered in every pregnancy from 16 weeks, usually around 20 weeks. Antibodies pass to your baby before they can have their own vaccines at 8 weeks. Pregnancy and baby vaccines
- Maternity Allowance claims open at 26 weeks. If you do not qualify for Statutory Maternity Pay, you can apply for Maternity Allowance once you have been pregnant for 26 weeks. Maternity leave and pay guide
What else is useful at 27 weeks?
Use the week page for size and symptoms; use the guides below for the decisions that actually sit in this window — pay, packing, car seats, labour signs.
27 weeks pregnant: common questions
When does the third trimester start?
At week 27–28 (definitions vary slightly; the NHS uses week 27). It runs to the birth, brings more frequent antenatal appointments, and is when tiredness often returns alongside heartburn and disturbed sleep as the baby takes up more room.
How big is my baby at 27 weeks pregnant?
At 27 weeks, your baby is approximately the size of a cauliflower, about 36.6cm and around 875g. These are approximate averages — every baby grows at its own pace.
What's happening at 27 weeks pregnant?
Welcome to the third trimester. The baby now sleeps and wakes at regular intervals and may hiccup (you'll feel rhythmic little jolts). Their lungs and brain are developing fast. For you: the final stretch begins. tiredness can return, along with heartburn, swelling and trouble sleeping. you may notice colostrum (early milk) leaking from your breasts.
What appointments or vaccines are due at 27 weeks pregnant?
Around 27 weeks: whooping cough vaccine; Maternity Allowance claims open at 26 weeks. Your maternity team will confirm the dates that apply to you.
Which trimester is 27 weeks?
27 weeks pregnant is in the third trimester. The first trimester runs to the end of week 12, the second from weeks 13 to 26, and the third from week 27 to birth.
Sources & further reading
This is general information, not medical advice — every pregnancy is different. For anything that worries you, and for all your antenatal care, speak to your midwife or GP. If your baby's movements ever slow down or change, contact your maternity unit immediately, day or night.