Week-by-week guide to pregnancy

group of pregnant women
When you're pregnant, you have lots of questions. Our week-by-week pregnancy guide is packed with lots of useful information. From what's happening inside your body, to how your baby is developing, and tips and advice on having a healthy pregnancy – this is your one-stop pregnancy guide!

2nd trimester

Our week-by-week pregnancy guide is full of essential information. From staying fit in pregnancy to advice on your maternity rights, you'll find it all here.

Week 20 – your 2nd trimester

You're halfway through your pregnancy now!

What's happening in my body?

You may have your anomaly scan this week. The sonographer will be checking your baby's development and will also examine your placenta (that's the pancake-shaped organ that feeds your baby and removes waste).

You might find yourself being woken up at night by sudden sharp pains in your calves. It's probably cramp, which is common in pregnancy and caused by muscular spasms. Rub the muscle hard or pull your toes up towards your ankle. Exercising more in the day could help you avoid this and you could try these foot exercises.

Whooping cough jab

Whooping cough is on the rise – but you can protect your baby from this dangerous condition by having a vaccination.

The NHS recommends that all pregnant women should have the jab, ideally between 16 and 32 weeks.

The immunity that you get will be passed on to your baby through the placenta and then offer protection until the routine jab that most babies have at 2 months.

Find out more about the whooping cough vaccination.

Maternity Certificate to claim maternity pay and benefits

Ask your doctor or midwife for a Maternity Certificate, also known as a MAT B1 form. It's issued from 20 weeks onwards. You'll need it to claim maternity pay and benefits.

2nd trimester pregnancy symptoms (at 20 weeks)

Your signs of pregnancy this week could include:

You may also experience symptoms from earlier weeks, such as:

Read Tommy's guide to common pregnancy symptoms.

What does my baby look like?

Your baby, or foetus, is around 25.6cm long, which is the size of a banana. Measurements are now taken from head to heel. In earlier weeks, babies are measured from the head to the bottom because the legs are curled up and hard to see. Your baby weighs around 300g. That's approximately the weight of 3 apples.

Your baby is now covered in a white, greasy layer of "vernix". It's thought that this protects their delicate skin from drying out in the amniotic fluid. This slippery layer also helps babies to make their way down the birth canal.

Your baby will be getting more active each day. As well as kicking, punching and turning around, your baby could be sucking their thumb – this develops their sucking reflex, which they'll need to feed once they're born.

You may start to feel a bubbling or fluttering in your belly – this could be your baby moving around.

Action stations

This week you could:

You don't have to tell your employer for several more weeks, but as soon as you do, you will have maternity rights. You can attend antenatal appointments during paid work time.

You can also ask for a risk assessment of your work place. If you want to wait, the latest you can leave it is 15 weeks before the baby is due, which is around week 25.

It's a good time to tone up your pelvic floor muscles. Gentle exercises can help to prevent leakage when you laugh, sneeze or cough. Get the muscles going by pretending that you're having a wee and then stopping midflow. Visit Tommy's for more ideas about pelvic floor exercises.

Ask your midwife or doctor about online antenatal classes – they may be able to recommend one. The charity Tommy's has lots of useful information on antenatal classes and preparing you for birth.

Ask your partner if they would like to take part in the antenatal classes. Even if you've had children before, they're still worth going to as you can meet other parents-to-be. The NCT offers online antenatal classes with small groups of people that live locally to you.

Do your best to stop smoking, give up alcohol and go easy on the tea, coffee and anything else with caffeine. Ask your midwife or GP for support if you need it.

To keep bones and muscles healthy, we need vitamin D. From late March/early April to the end of September, most people make enough vitamin D from sunlight on their skin. However, between October and early March, you should consider taking a daily vitamin D supplement because we cannot make enough from sunlight.

Some people should take a vitamin D supplement all year round, find out if this applies to you on the NHS website. You just need 10 micrograms (it's the same for grown-ups and kids). Check if you're entitled to free vitamins.

It's recommended that you do 150 minutes of exercise a week while pregnant. You could start off with just 10 minutes of daily exercise - perhaps take a brisk walk outside. Check out Sport England's #StayInWorkOut online exercises (scroll to the pregnancy section). Listen to your body and do what feels right for you.

There's no need to eat for 2. You don't need any extra calories until the third trimester, which starts in week 28. Try to eat healthily, with plenty of fresh fruit and veg, and avoid processed, fatty and salty foods. You may be able to get free milk, fruit and veg through the Healthy Start scheme.

You and your family should follow the government and NHS guidance on coronavirus (COVID-19):

  • read government guidance on how to stay safe from COVID-19
  • get NHS advice about COVID-19
  • use the NHS COVID-19 app for England and Wales – it's the fastest way of knowing when you've been exposed to COVID-19
  • To find out about about COVID-19 and pregnancy, childbirth and breastfeeding, have a look at advice on the:

  • NHS website
  • Breastfeeding Network
  • World Health Organization
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