Week 12, first trimester
12 weeks pregnant: your dating scan, your baby and what's next
At 12 weeks pregnant, your baby is fully formed and about 5.4cm long from head to bottom, roughly the size of a lime. All their organs, muscles and bones are in place, and from now on it’s mostly about growing. This is usually the week of your NHS dating scan (offered between 11 and 14 weeks), and for many people the nausea and tiredness of early pregnancy start to ease.
| At a glance | 12 weeks pregnant |
|---|---|
| Trimester | End of the first trimester |
| Baby’s length | About 5.4cm (head to bottom) |
| Baby’s weight | About 14g |
| NHS appointments | Dating scan (11 to 14 weeks), screening if you choose it |
How is my baby developing at 12 weeks?
Your baby now has everything they’ll be born with: a beating heart, kidneys that have started making urine, fingers and toes, and even the beginnings of fingernails. They’re moving a lot, flexing, stretching and even hiccuping, though they’re far too small for you to feel it yet.
The placenta is now taking over most of the job of producing pregnancy hormones and supplying your baby with nutrients. That handover is one reason many people start to feel better around now.
What happens at the 12-week dating scan?
The dating scan is an ultrasound, usually lasting around 20 minutes. The sonographer will:
- measure your baby to work out how many weeks pregnant you are and give you a more accurate due date
- check your baby’s heartbeat and early development
- check whether you’re expecting more than one baby
You may be asked to arrive with a fairly full bladder, as it can give a clearer picture. Your hospital letter will say. Most hospitals let you bring someone with you, and many sell printed scan photos, so it’s worth taking some change or a card.
Should I have the combined screening test?
At the same appointment you’ll be offered screening for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome. The combined test uses a blood test and a measurement of the fluid at the back of your baby’s neck taken during the scan.
Screening is your choice. Some people want as much information as possible, and some prefer not to have it. It’s worth talking it through with your partner and midwife beforehand. A screening result doesn’t tell you for certain whether your baby has a condition. It tells you whether there’s a higher or lower chance, and if the chance is higher you’ll be offered further tests.
How might I feel at 12 weeks pregnant?
Every pregnancy is different, but at 12 weeks you might notice:
- Nausea easing. For most people, sickness improves between 12 and 14 weeks. If you can’t keep food or fluids down, speak to your GP or midwife, as it could be hyperemesis gravidarum, which needs treatment.
- More energy, or at least a little less exhaustion.
- A thickening waist. Many people aren’t visibly showing yet, especially in a first pregnancy, but your usual clothes may feel tighter.
- Headaches, constipation or heartburn, all common side effects of pregnancy hormones.
What should I be doing this week?
- Keep taking your vitamins. The NHS recommends folic acid until 12 weeks and vitamin D throughout pregnancy.
- Think about who to tell. Lots of people share their news after the dating scan. If you’re working, you don’t legally need to tell your employer yet, but you do need to before you’re about 25 weeks (see our 20 weeks pregnant guide).
- Check your next appointment. You’ll usually see your midwife again at around 16 weeks.
What’s coming next?
Next week marks the start of the second trimester, which many people find the most comfortable stretch of pregnancy. Your next scan, the 20-week screening scan, takes a detailed look at how your baby is developing.
Appointments and key dates this week
- Booking appointmentUsually between 8 and 12 weeks
- Dating scanBetween 11 and 14 weeks
Day by day this week
- 12 weeks 0 days (day 84)You've reached the end of the first trimester, and in that time your baby has grown from a ball of cells into an active fetus.
- 12 weeks 1 day (day 85)This is a good time to start telling the important people in your life, before they guess for themselves.
- 12 weeks 2 days (day 86)The bag of amniotic fluid is your baby's home, keeping him safe and free from infection until he's ready to be born.
- 12 weeks 3 days (day 87)As your uterus grows to make room for your baby, you may notice a few twinges around your pelvis.
- 12 weeks 4 days (day 88)Complex brain development is gradually letting your baby become more responsive and mobile.
- 12 weeks 5 days (day 89)You and your partner will be developing your own special relationship with your baby.
- 12 weeks 6 days (day 90)It's never too early to plan what you'll need for your baby, even if you don't want to start shopping yet.
Common questions
When is the 12-week scan on the NHS?
The NHS dating scan is usually done between 11 and 14 weeks of pregnancy. Your maternity unit will send you an appointment after your booking appointment with your midwife.
Can I find out the sex at my 12-week scan?
Usually not. The NHS dating scan isn't used to tell you the sex of your baby. Some hospitals will tell you at the 20-week scan if the sonographer can see clearly and hospital policy allows it.
Do I still need to take folic acid at 12 weeks?
The NHS recommends taking 400 micrograms of folic acid every day until you're 12 weeks pregnant. It also recommends 10 micrograms of vitamin D a day throughout pregnancy.
Is it safe to tell people after the 12-week scan?
Many people wait until after the dating scan because the chance of miscarriage falls after the first trimester. There's no right time, though. Tell people when it feels right for you.
Sources
This is general information based on NHS guidance, not medical advice, and every pregnancy is different. Talk to your midwife or GP about anything that worries you. If your baby's movements slow down or change, or you have bleeding, severe pain or leaking fluid, call your maternity unit straight away. In an emergency, call 999.