🤰 First trimester
12 weeks pregnant
Your baby is about the size of a plum
By Emma Whitfield · Pregnancy & Baby Writer
Your baby at 12 weeks
Reflexes are developing — the baby will move if your bump is prodded, though you won't feel it. The digestive system is starting to practise contractions, and the kidneys produce urine.
Your body at 12 weeks
The end of the first trimester is in sight, and miscarriage risk drops significantly after the 12-week scan. Energy often starts returning.
Common symptoms this week
- Energy beginning to return
- Nausea easing
- A hint of a bump for some
Symptom lists are typical, never exhaustive — and having none of them is normal too.
Focus this week
Many people choose to share their news after the 12-week scan — but there's no right time. Do what feels right for you.
Week 12 checklist
- Attend your dating scan — your due date is set from the baby's measurements
- Decide who to tell and when — after the scan is common but there's no rule
- Photograph your scan picture rather than laminating it (heat fades them)
12 weeks pregnant: common questions
Is the 12-week scan the one that dates the pregnancy?
Yes — the dating scan (11–14 weeks) measures the baby crown to rump and sets your official due date, which usually replaces the date calculated from your last period. It also checks the heartbeat, detects twins and includes optional combined screening.
How big is my baby at 12 weeks pregnant?
At 12 weeks, your baby is approximately the size of a plum, about 5.4cm and around 14g. These are approximate averages — every baby grows at its own pace.
What's happening at 12 weeks pregnant?
Reflexes are developing — the baby will move if your bump is prodded, though you won't feel it. The digestive system is starting to practise contractions, and the kidneys produce urine. For you: the end of the first trimester is in sight, and miscarriage risk drops significantly after the 12-week scan. energy often starts returning.
Which trimester is 12 weeks?
12 weeks pregnant is in the first 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. Reviewed July 2026.