12 weeks pregnant

You and your baby's development

What's happening in week 12 of your pregnancy

You are in the final week of your first trimester and your baby has changed beyond all recognition from week one!

12 weeks pregnant

  • Your tiny baby is now 6cm in length and fully formed
  • Their eyelids remain fused shut
  • Wrists and elbows bend as baby moves around
12 Weeks pregnant

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How big is my baby at 12 weeks pregnant?

Your tiny baby is now a compact 5.4cm in length, and fully formed, although it is unlikely you would be able to get a reliable sexing at a scan just yet. The placenta is also now fully developed. They are moving around a lot at this stage, but you still won't be able to feel this for a while as they still have a lot of space to bob about in. 

Their eyelids remain fused shut at week 12 (they will open at around week 27), and their little wrists and elbows bend as they move around. 

Did you know?

  • By now, your baby is producing urine which is peed out into the surrounding amniotic fluid
  • Your tiny baby is now fully formed and around 5.4cm
  • Your baby's little wrists and elbows bend now as they move around
  • Baby's finger nails and toe nails are forming
  • As well as a developing skeleton, your baby's organs and intestines are now developing

You at 12 weeks pregnant

Week 12 marks the end of the first trimester and positively most women usually start to feel that they have more energy.

As your bump blossoms you may also be wondering about stretch marks as your pregnant body begins to adapt to your growing little one. 

They are common and can affect up to 90% of women. It’s a combination of hormonal changes and weight gain that can begin to cause the usually elastic middle layer of your skin (the dermis) to breaks in places, which then allows the deeper layers to show through. It’s this ‘breaking’ that causes the thin red or purple narrow streaks or lines that define stretch marks. However, once you’ve had your baby and everything begins to settle down you’ll soon find that these marks fade to a silvery white, or grey lines are less noticeable.

And if you've had your dating scan you are no doubt the very owner of a set of ultrasound images of your baby son or daughter!

Did you know?

  • Dribbling on your pillow at night? Excess saliva is common during pregnancy, particularly in the first trimester

What to think about in week 12 of pregnancy

Maternity leave might me a long way off yet, but you’re likely to be considering things like when to tell work, when you can take maternity leave, and how much maternity pay you’ll get as well as your rights in the workplace. At first glance it can seem confusing and a lot to take on board – but basically, the law is on your side!

It is against the law for employers to discriminate against mums and mums-to-be, and there is lots of legislation to protect you and your bump in the workplace.

Dads have rights too! As do same-sex partners and civil partners have the same rights as all parents. Although they do not have the right to paid time off before their baby is born, (such as for antenatal appointments). If they have been with their current employer continuously for at least 26 weeks by the end of the 15th week before the baby is due, they are entitled to paternity leave.

There are two types of paternity leave: 1 or 2 weeks paid Ordinary Paternity Leave and up to 26 weeks paid Additional Paternity Leave (if mum decides to return to work). This means that if you decide to return to work before your maternity leave has ended, your partner could be able to take Additional Paternity Leave of between 2 and 26 weeks, depending on how much unused maternity leave you have left over. This leave can start 20 weeks after the birth if you choose to return to work but must stop on your baby's first birthday.

Signs and Symptoms at 12 weeks pregnant


Even before you show real signs of a pregnancy bump, you can think you are showing as your belly bloats and later in the day your clothes feel tighter round the waistline.

Hormones cause the abdominal bloating and can cause your digestion to slow down leading to indigestion, trapped wind and other embarrassing symptoms.


It’s annoying but this common early pregnancy symptom may still be plaguing you. The cause can be as simple as your body adjusting to such huge changes a pregnancy brings. You may find if you suffered from headaches normally, they have gotten worse during your pregnancy. 

Do bear in mind that if you were a big caffeine drinker before you were pregnant and have cut a lot out, it could be caffeine withdrawal causing your headache, but stick with it and find out about coping with headaches in pregnancy

You might also like:

Watch our video below on:

Video 1 (NHS content): What pregnancy symptoms are normal? NHS Choices logo

Video 2: The first scan (12 weeks)

12 weeks pregnant

  • Your tiny baby is now 6cm in length and fully formed
  • Their eyelids remain fused shut
  • Wrists and elbows bend as baby moves around

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