12 weeks pregnant: baby development and your baby bump

At 12 weeks pregnant, you’re now at the end of your first trimester. Your baby’s looking less like a tadpole and more like a little person now, and as your hormones settle down, you might find that those early pregnancy symptoms start to ease¹.

Around now, you could also be about to reach another exciting milestone – seeing a noticeable baby bump².

Here’s everything you need to know about this week in your pregnancy journey, from some of the 12 weeks pregnant symptoms and your baby’s development to your 12 weeks pregnant ultrasound.

Reviewed by Sammy, a registered NHS midwife with a background in neonatal nursing, dedicated to providing compassionate, evidence based care to women and families throughout pregnancy, birth and the postnatal period.

You’re coming to the end of your third month of pregnancy, and – believe it or not – you’re about to enter your second trimester. If you’ve been feeling a little under the weather and lacking in energy, you may well find that this changes very soon¹.

While you might not be able to feel it yet, your baby’s also moving around a lot inside your womb at 12 weeks pregnant, and might even be starting to suck their thumb³.

Your baby is now 5-6cm long from their head to their bottom – around the size of a plum¹. All of their organs are limbs are in place now (although they still have a lot of growing to do before they’re born)³. By the time you’re 12 weeks pregnant, your baby’s sex organs are well developed, but you won’t be able to find out if you’re having a boy or a girl for another couple of months¹.

Your 12 weeks pregnant ultrasound scan (also called a 12-week scan or a dating scan) will probably be the first time you see your baby – this is when it can all feel a lot more real. 

The ultrasound scan will show⁴:

• Where your baby is in the womb.
• How they’re developing.
• How big they are (which can help give you a more accurate due date).
• Whether you’re expecting one baby, two babies, or even more!
• Your baby moving around and maybe even sucking their thumb.

At some hospitals, you can buy a photo from your ultrasound scan, which is great if you want a keepsake. It’s also an exciting way to share your news with family and friends. 

At your 12-week scan, you’ll also be offered a screening for conditions like Down's syndrome, Edwards’ syndrome, and Patau’s syndrome. This involves a blood test and a measurement of the fluid at the back of your baby’s neck based on the ultrasound scan. Whether you have this screening is a personal choice and totally up to you⁵.

Your little one is likely to be getting the nutrients they need from your placenta now, a brand new organ your body has grown specifically to support your pregnancy. This can mean your hormones start to settle down and your pregnancy symptoms ease up a bit¹.

You might start to notice your breasts, waist and appetite getting bigger around this time too¹. have a think about maternity clothes (including a well-fitting bra) and eating a balanced pregnancy diet to stay comfy and healthy at 12 weeks pregnant.

At 12 weeks pregnant, symptoms like morning sickness and mood swings could well be sticking around¹.

You might also notice symptoms and body changes like¹:

• A metallic taste in your mouth
• Heartburn
• Bloating
• Sore breasts
• A white, milky vaginal discharge
• Light spotting or cramping (speak to your doctor or midwife if you notice bleeding or severe abdominal pain)
• Greasier skin
• A sharp cramp on one side of your stomach⁶

If you’re pregnant with your first baby, you might notice a visible baby bump for the first time at 12 weeks pregnant². This is often around the time parents-to-be tell their loved ones their exciting news, as soon it’ll become pretty obvious!

If you’ve been pregnant before, your bump might show before 12 weeks because your muscles could still be stretched from your last pregnancy².

Try not to worry about when your baby bump will show, or about the size of your 12 weeks pregnant bump – everyone’s different. The size of your baby bump can depend on lots of things, like your hormones, how many times you’ve been pregnant, and how strong your muscles are¹.

At 12 weeks pregnant, your bump will probably still feel fairly manageable. As the weeks go by and your baby grows, your bump will grow with it, and you might start to notice:

• Back pain as your bump puts pressure on your pelvis⁷
• Trouble finding a comfy sleeping position8)
• Growing pains as your ligaments stretch to support your baby bump⁶
• Feeling a little unsteady on your feet as your centre of gravity shifts⁹
• Itchy skin where it stretches over your growing tummy¹⁰

As you move into your second trimester and your 12 weeks pregnant belly becomes a sizeable baby bump, there are some things you can do to help ease any discomfort:

• Spend more time resting with your feet up⁸
• Support your bump with pillows when lying down, and use an extra pillow between your knees⁸
• Keep your back straight and supported when you’re sitting down⁷
• Use an unperfumed moisturiser to help soothe any itching¹¹