12 weeks pregnant: Baby’s development, symptoms and more

At 12 weeks, your baby has grown again and is now about 5.4 cm long from head to bottom – and still quite curled up in there. In fruit terms, it’s about the size of a lime, but the weight of just three grapes – 18g.

Unbelievably, your tiny foetus is fully developed at 12 weeks. Every little detail is in place, from the sex organs to the fingernails, and now all your baby needs to do is get bigger and get those organs functioning ready for life on the outside.

From next week, the baby will begin swallowing amniotic fluid – good practice for that first feed. (And yes, babies do pee in the womb!) There’s more digestive action to come, even within the next two weeks, but this week the big news is the intestines are moving back inside the abdomen.

For many mums-to-be, morning sickness is fading by 12 weeks and they are feeling less fatigued. Foods that once had you running for the toilet may have become tolerable again, and your sense of smell may be less sensitive.

However, some of those sensory aversions may stick with you throughout pregnancy, or even turn up unannounced (and uninvited!) in your second trimester. This is all perfectly normal and can, once again, be blamed on hormone fluctuations. (Though if you do start having seriously odd cravings, mention it to your midwife – it could be a sign that you’re not getting enough nutrients in your diet.)

Bloating at 12 weeks pregnant

Bloating, gas and constipation may be your constant companion throughout the rest of your pregnancy, unfortunately. This is partly due to the hormone progesterone helping to slow the gastrointestinal tract – and thus allowing your baby to get more of the goodness in the food you eat – but will increasingly also be due to the size of your uterus, which will soon grow big enough to put pressure on your other organs, like your stomach and your rectum.

Look out for exercises that help get those bowels moving, or try gentle walks, peppermint tea, or a nice warm bath.

Is it bump time yet?

You might begin to notice a bit of a bump this week – although it’s more weight gain than baby at this point as your body increases its fat reserves. You’ll probably see it long before other people, which can be frustrating. Get comfy in your maternity wear and don’t worry. It’s all part of growing a baby. If it’s not your first pregnancy, you’ll show sooner, as your body is already primed to grow!

If you’d like to keep an eye on your weight during this period, our pregnancy weight chart shows roughly how much weight you should be gaining throughout your pregnancy, according to your pre-pregnancy weight.

Remember, there’s never a point in your pregnancy when you’re actually eating for two, so don’t overdo it. Try to stick to a healthy, balanced diet and remember to keep active.

Even now the baby’s foundations are all in place, it’s still important to look after yourself by sticking to a healthy, balanced diet, taking your vitamins and staying hydrated. Good nutrition not only supports the baby’s development, but also puts you in the best possible place to cope with the demands of pregnancy and childbirth.

Vaccinations

And talking of keeping healthy, you will have been offered various vaccines by your GP or midwife. Vaccination against flu, COVID and whooping cough is recommended for pregnant women because of the greater risk of developing complications while pregnant, which can be harmful for you and the baby.

You can have the flu and COVID vaccine at any point during pregnancy, while the whooping cough vaccine is recommended between 16 and 32 weeks. If you’re not sure about vaccinations, talk to your midwife. They will be able to talk you through your options, pros and cons. Why not include it in your list of questions to ask at your next appointment?

Pelvic floor exercises

It’s never too early to start pelvic floor exercises. Your pelvic floor is going to bear the brunt of this pregnancy over the next 6 months, and through the birth itself. The more you can strengthen it, the better you can prepare your body to withstand that pressure and recover well afterwards.

Try to make pelvic floor exercises part of your routine – like, whenever you brush your teeth, or every time you make a phone call. Our pelvic health expert has some great tips to share.

Tips for partners

12 weeks is also a special milestone for your partner. Attending the ultrasound together and seeing your tiny baby on the monitor is an incredible experience and – for some partners – a ‘seeing is believing’ moment where they realise the theoretical baby they’ve been hoping for/dreaming of/panicking about is really real.

Putting the scan photos somewhere prominent is a great way to reinforce that feeling. Encourage your partner to share their hopes, fears and other feelings with you, just as you are with them. Keeping those lines of communication open is such an important foundation to the parenting relationship.

What to expect at 12 weeks pregnant?

At 12 weeks pregnant you can expect to feel some relief from those early pregnancy symptoms – though for some people they do hang around for another few weeks or more.

Though you won’t be able to feel the baby yet, you will probably begin to see a change in your appearance as your waistline thickens and the first hint of a bump appears. How quickly you show depends on a number of factors, none of which relate to how well the baby’s doing, so don’t worry if you don’t show for a few weeks yet.

Is stomach pain normal at 12 weeks pregnant?

You will probably experience fairly regular twinges now and throughout your pregnancy, where your muscles and ligaments spasm or stretch with your growing belly. This can be quite painful, but is usually a short sharp pain brought on by sudden movements like coughing, sneezing, or laughing. If you have more prolonged, severe pain, bleeding, or any other concerning symptoms, contact your midwife.

Is 12 weeks safe to announce a pregnancy?

At 12 weeks pregnant, you’ve reached an important milestone in your pregnancy where the risk of miscarriage has dropped significantly. Often, people wait to see the scan and get the reassurance that everything is progressing well with the pregnancy before making any announcements.

It’s important to note, though, that you’re under no obligation to announce anything until you feel comfortable doing so – nor must you wait until 12 weeks if you are eager to share your news and receive the support of family, friends and colleagues. When it comes to announcing your pregnancy, you should always go with what feels right to you.

How big is my uterus at 12 weeks pregnant?

At 12 weeks pregnant, your uterus has grown to the size of a grapefruit.

Where is your baby in your belly at 12 weeks?

At this stage in your pregnancy, your baby is still floating around with plenty of room to kick, dance and wave. Your uterus is still relatively small and low in your body. Your midwife will be able to feel the top of it by your pubic bone.

Got questions? At the HiPPBabyClub, we bring you real-world advice and support from HiPP parents, midwives, nutritionists and more. Join our Baby Club to find out more.