Week 20, second trimester
20 weeks pregnant: your anomaly scan, MATB1 and the halfway point
At 20 weeks pregnant you’re halfway through. Your baby is about 25cm from head to heel and weighs around 300g, roughly the length of a banana. This is usually the time of your NHS 20-week screening scan (between 18 and 21 weeks), you’ll be offered the whooping cough vaccine, and you can now get your MATB1 form for maternity pay.
| At a glance | 20 weeks pregnant |
|---|---|
| Trimester | Second trimester, halfway |
| Baby’s length | About 25cm (head to heel) |
| Baby’s weight | About 300g |
| NHS appointments | 20-week screening scan (18 to 21 weeks) |
| Also this week | Whooping cough vaccine, MATB1 form available |
How is my baby developing at 20 weeks?
Your baby is covered in a fine, soft hair called lanugo and a white, waxy coating called vernix, which protects their skin from the amniotic fluid. They can hear sounds from outside your body, including your voice, and they’re swallowing amniotic fluid, which is good practice for their digestive system.
They’re also moving more. If this is your first baby you may have just started feeling flutters, or you may not feel anything until closer to 24 weeks, which is completely normal. People who’ve been pregnant before often notice movements earlier.
What does the 20-week scan check?
The 20-week screening scan looks in detail at your baby’s bones, heart, brain, spinal cord, face, kidneys and abdomen. It checks for 11 specific physical conditions. The scan usually takes 20 to 40 minutes, and sometimes the sonographer will ask you to come back if your baby is in an awkward position.
The scan also checks where your placenta is. If it’s low-lying, you’ll be offered another scan later in pregnancy to see whether it has moved up.
Most scans show that everything is developing as expected. If the sonographer finds something that needs a closer look, they’ll explain what happens next and you’ll usually be referred to a specialist quickly.
Which vaccines should I have at 20 weeks?
The NHS usually offers the whooping cough (pertussis) vaccine around 20 weeks. It can be given from 16 weeks, and it’s best to have it before 32 weeks so your baby gets the most protection in their first weeks of life. Your GP surgery or midwife will arrange it.
If it’s flu season, you’ll also be offered the free flu vaccine, which is safe at any stage of pregnancy. The RSV vaccine comes later, from 28 weeks.
Maternity pay and work: what to do now
- Get your MATB1 form. Your midwife or GP can issue it from 20 weeks before your due date. You’ll need it to claim Statutory Maternity Pay from your employer, or Maternity Allowance if you’re self-employed or don’t qualify for SMP.
- Plan when to tell your employer. You must tell them by the 15th week before your baby is due, around 25 weeks pregnant. Telling them earlier means you’re protected and can take paid time off for antenatal appointments.
- Apply for your maternity exemption certificate, if you haven’t already. It gives you free NHS prescriptions and dental care during pregnancy and for 12 months after your due date. Ask your midwife or GP for the form.
How might I feel at 20 weeks pregnant?
- A visible bump. Most people are showing by now.
- Backache and round ligament pain, sharp twinges at the sides of your bump as the ligaments stretch.
- Leg cramps, often at night.
- More energy, for many people. The middle of pregnancy is often the most comfortable.
What’s coming next?
If this is your first baby, you’ll see your midwife at around 25 weeks. At 28 weeks you’ll have blood tests, be offered the RSV vaccine and, if you need it, an anti-D injection. Read our 28 weeks pregnant guide for what to expect.
Appointments and key dates this week
- 20-week screening scanBetween 18 and 21 weeks
- Whooping cough vaccineUsually around 20 weeks, best before 32 weeks
- MATB1 form available
Day by day this week
- 20 weeks 0 days (day 140)Congratulations, you're halfway through your pregnancy. In about 20 weeks, you'll be a mom.
- 20 weeks 1 day (day 141)You're in the second half of your pregnancy, and you'll see your doctor more regularly in the months ahead.
- 20 weeks 2 days (day 142)Twins have been sharing a home in the uterus for a while now, but how do they relate to each other?
- 20 weeks 3 days (day 143)Part of the fun of not knowing your baby's sex is guessing, but be ready for everyone else to guess too.
- 20 weeks 4 days (day 144)There are few better ways to ease pregnancy aches and pains, and to unwind, than a soothing massage.
- 20 weeks 5 days (day 145)Your baby becomes more responsive and aware every day as his nervous system starts working more effectively.
- 20 weeks 6 days (day 146)Your baby's reproductive organs are gradually developing, and the differences between the sexes are more obvious.
Common questions
When is the 20-week scan?
The NHS 20-week screening scan, also called the anomaly scan, is usually done between 18 and 21 weeks of pregnancy.
Will they tell me the sex at the 20-week scan?
It depends on your hospital. Many will tell you if you ask and the sonographer can see clearly, but some hospitals have a policy of not saying. It's not always possible to tell, so it's best not to count on it.
When can I get my MATB1 form?
Your midwife or GP can give you a MATB1 certificate from 20 weeks before your due date, so from around 20 weeks pregnant. You need it to claim Statutory Maternity Pay or Maternity Allowance.
When should I tell my employer I'm pregnant?
You must tell your employer at least 15 weeks before the start of the week your baby is due, which is around 25 weeks pregnant. You need to give your due date and when you want your maternity leave to start.
Sources
This is general information based on NHS guidance, not medical advice, and every pregnancy is different. Talk to your midwife or GP about anything that worries you. If your baby's movements slow down or change, or you have bleeding, severe pain or leaking fluid, call your maternity unit straight away. In an emergency, call 999.