12 weeks pregnant: Pregnancy Symptoms & Baby Development

At 12 weeks pregnant, you’re about to enter your second trimester. Around about now, like many pregnant women, you might find that some of the unpleasant symptoms of pregnancy start to ease, and you’re feeling a little more energetic¹.

As for your baby, their rapid development continues as they focus on getting bigger.

Let’s look a little closer at your baby’s development, what’s happening for you and your body at 12 weeks pregnant, and the importance of omega-3 and omega-6 for a healthy pregnancy diet.

Your baby, also known as a foetus at 12 weeks pregnant, is almost fully formed. Each one of your baby’s limbs, muscles, bones and organs is now in place - including their sex organs, although it’s still a little too soon to be able to tell what sex your baby will be just yet, as this is unlikely to show up on an ultrasound scan. You may, however, be able to hear your baby’s heart beating on your 12-week scan¹.

At 3 months pregnant, your baby is most likely getting all of the nutrients they need from the placenta, which has taken over the job from the yolk sac¹. 

Although you’re unlikely to feel anything at 3 months pregnant, your little one is moving around a lot in your uterus and can now even make a fist with their tiny hands². You’ll be able to see them wriggle, kick and squirm on screen when you go for your scan⁴. 

Your baby is around 5.4 cm long at 12 weeks pregnant and is about the size of a small plum¹. Their head is still very big in comparison to their body, but their tiny facial features are becoming more defined³. 

Your baby’s eyelids are now closed, and it won’t be until around week 28 of your pregnancy that they’ll start to open again. There are nails on the fingers and toes, and your baby’s milk teeth are sitting within their gums - all ready for when they start teething³.

You’ll usually be offered two pregnancy scans. The first is known as the 12-week scan or ‘dating scan’ because it will help to estimate your baby’s due date. It will be offered between 11 and 14 weeks of pregnancy⁴. During the appointment, the sonographer can also perform a nuchal translucency scan, which forms part of the screening tests for Down’s syndrome⁴. 

The second scan, also known as the 20-week scan or ‘anomaly scan’, is offered between 18 and 21 weeks and checks how your baby is developing physically⁴.

It’s your choice whether or not to go to your scans, and whatever you decide, you’ll still receive your antenatal care. If you have any questions or concerns, don’t hesitate to chat with your healthcare provider⁴.

Now that the placenta is feeding your baby, your body's hormones may settle down a little, leaving you feeling better and with more energy¹.

You might notice that your waist is getting thicker at 12 weeks pregnant, and that your breasts are getting larger. At the end of the first trimester, you may not yet have a visible 12-week bump or look like you’re pregnant. If you’re wondering how big your baby bump is likely to be, this depends on several factors, including¹:

• Whether you’ve been pregnant before, and how many babies you’ve had.
• Pregnancy hormone.
• How strong your muscles are.
• Your pre-pregnancy weight.

Feeling hungrier? This is very common as you enter your second trimester. Do your best to follow a healthy pregnancy diet and remember there’s no need to eat for two¹.

From tiredness and fatigue to constipation and bloating, let's take a look at some of those 12-week pregnancy symptoms.

During your pregnancy, you may experience inflamed and bleeding gums. This is down to pregnancy hormones making you more sensitive to plaque. It’s a good idea to visit your dentist during pregnancy to ensure your teeth and gums are healthy¹⁶.

You’re entitled to free dental care while pregnant and the first year after your baby is born. Speak to your midwife to ensure you’ve been issued your maternity exemption certificate¹⁶.

If you’ve had your first scan, you may feel ready to tell your employer about your pregnancy. Consider what your working life will look like, the amount of maternity leave you intend to take, and your rights and entitlements.

By now, you’ll likely have had your booking appointment with your midwife, who will have provided lots of helpful information about having a healthy pregnancy. This includes any supplements or prenatal vitamins you should take to support a healthy pregnancy.

As well as the 400 mcg of folic acid that you will have been advised to take for the first 12 weeks of your pregnancy, you should also be taking a daily vitamin D supplement¹⁷.

Exercise has many benefits during pregnancy, so if you feel up to it, try to stay active.

Pelvic floor exercises can be done when you’re standing, sitting or lying down, and will help to keep your muscles strong during pregnancy, birth and post-birth. Other safe exercises during pregnancy include running, yoga, swimming, and strength and weight training.

There are no official guidelines about how much weight you should gain during your pregnancy. However, most pregnant women tend to gain around 10 -12.5 kg across their entire pregnancy, with most of that taking place partway through their second trimester (from approximately 20 weeks).

Most of this weight gain is made up of¹⁸:

• Your growing baby.
• Your uterus and placenta
• Additional blood in the body.
• Your breasts getting larger. 

While some women are comfortable telling people about their pregnancy from the moment they find out, others prefer to wait until after their 12-week scan. This is because they prefer to have confirmation that their pregnancy is progressing well, and because some research has shown that the risk of miscarriage is reduced significantly after week 12 of pregnancy¹⁹.

Whilst this might be termed a ‘rule’, there’s no right or wrong here, and it’s entirely your choice when you tell people about your pregnancy. 

While you won’t be told your baby's gender at your routine 12-week scan, you can ask your sonographer to tell you when you have your second scan at 20 weeks.

You can opt to pay privately for a gender scan at 12 weeks pregnant, but bear in mind that it’s still early days, and you’re likely to get a more accurate answer a little later in your pregnancy – more specifically from around 15 weeks.