Second trimester
17 weeks pregnant
Your baby is about the size of a turnip
- 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 17 weeks pregnant?
At 17 weeks pregnant, your baby is about the size of a turnip, roughly 13cm and around 140g. Fat stores are beginning to develop under the skin, and the umbilical cord is growing stronger and thicker. The skeleton is changing from soft cartilage to bone. These are typical averages — your midwife's measurements are the ones that matter for your pregnancy.
What might you feel at 17 weeks?
Most people at 17 weeks notice some mix of the symptoms below — and plenty notice none of them. Your centre of gravity is shifting, which can affect balance. Some notice increased vaginal discharge (normal) and stronger Braxton Hicks awareness later on. None of this is a diagnosis; contact your midwife if something worries you.
Common symptoms this week
- Shifting balance as the bump grows
- More vaginal discharge (normal if clear/white and not itchy)
- Warmer, sometimes flushed skin
Symptom lists are typical, never exhaustive — and having none of them is normal too.
What should you do at 17 weeks pregnant?
The useful job this week is practical, not medical. Think about maternity clothes or bump bands — comfort matters more than buying lots. Borrowed and second-hand maternity wear is a smart saving. Pair it with the NHS week-by-week guide if you want a second description of the same stage.
Week 17 checklist
- Sort comfortable maternity basics — a bump band extends normal trousers for months
- Browse second-hand maternity wear before buying new
What antenatal care is due around 17 weeks?
These appointments, vaccines and deadlines fall around this stage. Your maternity team will confirm your own dates.
- Quadruple test if you missed combined screening. If you are past 14 weeks, the NHS may offer the quadruple blood test between 14 and 20 weeks. It checks for Down's syndrome but is not as accurate as the combined test. NHS: screening in pregnancy
- 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
- 20-week scan (usually 18 to 21 weeks). The mid-pregnancy scan screens for 11 physical conditions and takes around 30 minutes. It cannot find every condition, and it is your choice whether to have it. What the 20-week scan checks
What else is useful at 17 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.
17 weeks pregnant: common questions
Is increased discharge normal in pregnancy?
Yes — thin, clear or milky discharge increases through pregnancy and is protective. See your midwife or GP if it becomes itchy, smelly, green/yellow, or watery enough that you suspect leaking waters — those need checking, and thrush in pregnancy has specific safe treatments.
How big is my baby at 17 weeks pregnant?
At 17 weeks, your baby is approximately the size of a turnip, about 13cm and around 140g. These are approximate averages — every baby grows at its own pace.
What's happening at 17 weeks pregnant?
Fat stores are beginning to develop under the skin, and the umbilical cord is growing stronger and thicker. The skeleton is changing from soft cartilage to bone. For you: your centre of gravity is shifting, which can affect balance. some notice increased vaginal discharge (normal) and stronger braxton hicks awareness later on.
What appointments or vaccines are due at 17 weeks pregnant?
Around 17 weeks: quadruple test if you missed combined screening; whooping cough vaccine; 20-week scan. Your maternity team will confirm the dates that apply to you.
Which trimester is 17 weeks?
17 weeks pregnant is in the second 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.