20 weeks pregnant: pregnancy symptoms and your baby’s development

It might be hard to believe, but at 20 weeks pregnant, you’re now halfway through your pregnancy. With your baby focused on growing bigger and gaining weight, you might be getting ready to see them again on screen at your 20-week scan, which is also known as the anomaly scan.

Here, you can explore the exciting developments happening for your baby this week, along with some common pregnancy symptoms, including leg cramps, heartburn, and constipation. We’ll also look at the changes happening to your body at 20 weeks pregnant and why calcium is vital to a healthy pregnancy diet.

During the second trimester, there’s a lot going on in terms of foetal development as your baby continues to gain weight in preparation for birth.

At 20 weeks pregnant, your baby is becoming more active, and you may already be feeling them rolling and tumbling as they punch, kick and turn in your uterus. As your pregnancy progresses, your baby will settle into a sleep-wake cycle, usually around 22 weeks¹.

If you’re due for your next ultrasound scan, you may notice that your baby has started thumb sucking. This will help the sucking reflex they’ll need for feeding develop².

If you’re having a baby girl, her uterus will be developing, and her ovaries will already have seven million primitive eggs in them - two million of which she’ll be carrying when she’s born³. If you’re having a baby boy, then this is the week when the testes start lowering from his abdomen, dropping from the scrotum at around 26 weeks⁴.

At 20 weeks pregnant, your baby (still referred to as a foetus) is approximately 25.6 cm long, and is around the size of a banana². Your baby’s size is now measured from their head to the heels of their tiny feet. This is instead of head to bottom, a measurement used earlier on in pregnancy when your baby’s legs were curled up and difficult to see².

Your baby’s skin will now be covered with vernix (also known as vernix caseosa), a fatty, white and greasy substance that protects your baby’s skin from drying out in the amniotic fluid. It will also make it easier for your baby to ease down the birth canal when you go into labour².

The placenta is working hard at 20 weeks pregnant, passing nutrients and oxygen to your baby and removing waste products⁵.

Whilst more common in later pregnancy, you may start to experience Braxton Hicks contractions, sometimes called practice contractions. Unlike the real thing, Braxton Hicks are irregular and don’t last for long. They may feel uncomfortable or a little like a ‘tightening’, but they’re generally not painful⁶.

If you start to experience pain that becomes more severe or is accompanied by bleeding, always seek advice from your doctor or midwife at the maternity unit, as this could be a sign that you’re in early labour.

At 20 weeks pregnant, your baby bump is becoming more noticeable. Many women see a dark line develop down the middle of their tummy at this point, something known as the ‘linea negra’. This is completely normal and is down to the skin pigmentation changing as your baby bump gets bigger².

Around about now, you might also notice that hair feels thicker and shinier². 

Now that you’re at the halfway mark, let’s explore some common pregnancy symptoms. 

Exercising during pregnancy has a number of benefits for you and your baby. As long as your doctor or midwife has not advised otherwise, there’s no reason why you can't fit regular exercise into your daily routine¹⁸.

Whether you’re already doing regular exercise or you’re a complete beginner, it’s always a good idea to run your intended exercise plan by your healthcare provider. That way, you’ll know you’re exercising safely and at the right level.

As a general rule of thumb, you should be able to have a conversation during exercise easily. If you struggle for breath, it’s a sign that you’re overdoing things.

Some great exercises you can enjoy during your pregnancy include:

• Walking for 30 minutes every day¹⁸. However, do what feels comfortable for you, as any level of exercise is beneficial.

• Yoga. Pregnancy yoga will help ease tension, relax your muscles, and enable you to practise breathing techniques¹⁹.

• Swimming is a good pregnancy exercise as it supports the weight of your growing bump¹⁹.

If you've opted to have one, it might be time for your anomaly scan this week. This is also known as the 20-week scan, and it determines how your baby is developing physically. It’s also an opportunity for the sonographer to check that your placenta is functioning correctly (2). You can also find out the sex of your baby during the scan.

At the anomaly scan, the sonographer will look closely at your baby's abdomen and kidneys, spinal cord, bones, heart and brain, to make sure they’re developing normally. While it can’t pick up on every condition, it will check for²:

• Spina bifida.
• Cleft lip.
• Serious heart abnormalities. 
• Edwards’ and Patau’s syndrome
• Anencephaly.

You’ll be supported throughout the ultrasound scan, and in most cases, everything is as it should be. However, if there’s a cause for concern, a doctor may take a closer look and advise you about any necessary next steps.

If you plan to attend an antenatal class, you should explore what’s available in your local area. Your midwife may be able to help here and let you know your options.

Other things to think about include:

• Making a birth plan.
• Thinking about how you’ll look after your physical health and mental wellbeing after the birth of your baby – this is known as a postnatal plan.
• Eating a healthy, balanced diet.
• Deciding whether or not to have a birth partner present when your baby is born.
• The things you’ll pack in your hospital bag.

At 20 weeks pregnant, you’re in month 5 of your pregnancy. Your second trimester starts at week 13 and ends at week 26.

By week 12 of your pregnancy, your baby’s limbs, muscles, bones and organs are in place. However, your baby still has a lot of growing to do, and your pregnancy isn’t considered viable until week 24²⁰.

You should avoid several things throughout your pregnancy to ensure you and your baby are healthy. There are certain foods to avoid in pregnancy, for example, as well as caffeine, alcohol, and smoking.

If you’re struggling with some of the things you’re advised to avoid in pregnancy, now is the time to have a chat with your midwife about strategies that can help.

Certain leisure activities are best avoided until after your baby is born, too. For example¹⁹:

• Sports where your baby bump could get hit. For example, tennis and squash.
• Activities where you could be thrown, for example, horse riding or skiing.
• Hot tubs, jacuzzis and saunas.
• Diving and scuba diving.