The complete guide to antenatal scans and tests

From the moment you see that blue line, the joy of pregnancy can give way to anxiety as you face the barrage of ante-natal tests routinely offered to mums-to-be. The professionals are understandably keen to check you and your unborn baby for everything from high blood pressure to Down’s Syndrome. But each test can be a worrying time. 

‘The screening is meant to give you peace of mind but with your baby’s health at stake, it’s no wonder they can leave mums more stressed than stress-free,’ says midwife Breedagh Hughes.
‘The chances of a worrying result are very slim and the vast majority of women have trouble-free pregnancies.
‘And if the tests do highlight any potential problems, in many cases you can receive treatment to put things right. And in the unlikely event of a worst case scenario, such as finding out your baby does have a disability, knowing about it in advance will help you to deal with it as best you can.’

As with all things pregnancy, being armed with information helps. Here we’ve rounded up everything you need to know about the six key antenatal tests.

Blood pressure checks

When: From your very first midwife’s appointment at about 10 –12  weeks (often called your booking appointment) and at every routine visit from then on.
Why? High blood pressure is linked to low birth weight and premature birth. It’s also a first sign of pre-eclampsia, a serious pregnancy complication which affects the baby’s growth and can be life-threatening to both mum and baby if untreated.
What happens? The midwife takes blood pressure by pumping up a large Velcro band around your upper arm.
Results: On the spot
How to prepare: ‘Try to stay calm as ‘white coat syndrome’ can drive blood pressure up. If you’re anxious and feel it may be affecting your result, you can request a home visit to take your blood pressure in a more relaxed environment,’ says Breedagh Hughes.

Urine tests

When: Every midwife appointment. 
Why? Urine infections can affect your baby. Traces of protein (albumin) in your urine can be a sign of pre-eclampsia (see above). Sugar in your urine can be a sign of gestational diabetes, a condition that develops in pregnancy and can harm you and your baby. It can be controlled by change of diet and occasionally insulin and it usually disappears after birth.
What happens? The midwife will give you a small plastic pot to take to the loo. Start weeing, then hold the pot underneath you to collect your sample.
Results: On the spot
How to prepare:  ‘Just make sure you don’t arrive at the appointment having already emptied your bladder. If you’ve got problems weeing on demand, you can ask for some sample pots to fill at home and bring in to your midwife appointments,’ says midwife Gail Johnson.


Your first blood test

When:  At your booking appointment
Why? To test for:
Rhesus negative blood type. If you’re rhesus negative, it’s not usually a problem for first pregnancies but can be for subsequent ones. You may need an injection (called ‘anti-D’) after your first baby’s birth to protect future babies from anaemia.
Your immunity to German measles/rubella. Can cause deafness, blindness, brain and heart damage in unborn babies.
Hepatitis B, HIV or Syphilis. You can avoid transmitting these to your baby if you know in advance.
Anaemia. This can make you tired and less able to cope with losing blood during labour. If so, you’ll be offered iron and folic acid supplements.
What happens? A needle is inserted into a vein in the crook of your elbow and up to four vials of blood will be taken.
Results: You’ll only be contacted if there’s a problem. If you haven’t heard anything for two weeks, consider yourself in the clear.

Dating scan

When: At  10 - 12 weeks.
Why? Your first ultrasound scan checks that your pregnancy’s going well and uses measurements of your baby to calculate how pregnant you are and your due date. It also checks for abnormalities in the baby’s spine and brain. It’s the time when you’ll find out how many babies you’re having.
Some areas also offer what’s called a Nuchal Translucency Scan (NTS) as part of this ultrasound. NTS checks for the likelihood of your baby having Down’s Syndrome. The NTS measures the thickness of the nuchal pad at the back of your baby’s neck, as it’s usually thicker in babies with Down’s. This test calculates your risk of having a baby with Down’s but cannot say definitively whether you’re affected. You’ll be told straight away if the NTS suggests you’re at high risk (above one in 250) and if so, you’ll be offered an amniocentesis.
Nuchal Translucency Scans must be done before week 14, after which they become inaccurate. If your area doesn’t offer NTS, you could search online for a private antenatal clinic near you, where the scan will cost around £100.
What happens? Some gel is squirted onto your belly. A trained sonographer will then rub a handheld scanner over your bump to reveal an on-screen picture, with sound.
Results: On the spot
How to prepare:  ‘Wear separate tops and bottoms for easy access. Take your partner, husband or friend along, just in case you need support. It’s a good idea to go in with a full bladder – it makes the baby much more visible,’ says Breedagh Hughes.
Many hospitals ask you to pay a small amount for the scan pictures, so remember to take along some cash. Depending on where you live, you may be able to see  - and buy - 3D footage of your baby.

Second blood tests

When:  At around week 16
Why? The second blood test screens for ‘markers’ (biological signs) of Down’s Syndrome and other chromosomal/genetic disorders and is often known as the serum test or the Double, Triple or Quadruple test depending on how many markers are checked.
You’ll also send off a blood sample for a Spina Bifida test, also known as the alpha-fetoprotein (AFP) test,
What happens: You’ll provide a blood sample via needle. It’s sent off for analysis and when you get the results, they’ll be in the form of a risk evaluation of your chances – say one in 5,000.
Results: You’ll only be contacted if there’s a problem. If two weeks pass, consider yourself in the clear. If you’re found to have a high risk of Down’s (higher than one in 250) or other chromosomal problems, you’ll be offered an amniocentesis (see below). If you have a high level of AFP, you’ll be offered an ultrasound to check the baby’s developing spine.
How to prepare:  ‘Remember that these tests are offered routinely and there’s no need to assume you’re at risk. Also, they are not compulsory and if you don’t want to, say, find out if your baby has Down’s, you can decline it and won’t be pressured.
‘If you do decide to have these tests, it’s a good idea to think (and perhaps discuss with your other half) what you would do if the results indicate a high risk of abnormalities,’ says midwife Gail Johnson.

Anomaly scan

When: Around 20 weeks.
Why:  To check that your baby’s limbs and organs are all developing as they should, while looking out for specific ‘markers’ of abnormalities.
What happens: Exactly as with your first ultrasound scan (see above for Dating Scan).
Results: On the spot
How to prepare: ‘Try not to worry too much but do take someone to support you. Be prepared to get emotional – it can be quite magical to see your fully-formed baby appear on screen. Most hospitals ask that you don’t bring your older children with you to an ultrasound as they may distract the sonographer.,’ says midwife Breedagh Hughes.

Extra tests

There are two tests for Down’s Syndrome and a series of other chromosomal and genetic abnormalities that are offered if screening or your family history indicates that you’re at high risk. Chorionic Villus Sampling (CVS) is carried out up until week 14 and amniocentesis until week 20. Both tests involve inserting a needle into your womb, usually while you’re awake, using local anaesthetic, via your bump to remove cells for testing. CVS removes placenta cells; amniocentesis takes amniotic fluid.
Both tests carry a small risk  (between 0.5 and one per cent) of causing miscarriage, which is why they’re not offered routinely. You’ll have to wait about 10 days to two weeks for the results.
‘Waiting for the results can be very difficult but your midwife will counsel you and there’s no rushing the tests, they’ve got to be done properly,’ says midwife Breedagh Hughes.