The number of ultrasound scans you have in pregnancy depends on your healthcare provider and any concerns about your health or your baby’s. The UK’s NHS offers two routine ultrasound scans focused on the baby’s health: the dating scan and the anomaly scan. You may be offered more if your pregnancy is high-risk. You can usually book more if you’re being cared for privately and you want them.

The first routine scan happens between eleven and fourteen weeks of pregnancy and is known as the dating scan. Genetic screening happens at this stage, with the parents’ consent. It’s usually too early to see the baby’s sex, and some hospitals have a policy against telling you what this is, even when they can have a good idea, so if gender information is important to you, you’ll need to check in advance.

At this first scan, the sonographer is checking to make sure your baby is growing, as well as how many babies there are (!) in the uterus. The baby is measured from head to rump, and this helps determine their gestational age so that a due date may be calculated.

The development of the baby and certain structural characteristics, such as how the skull is growing, will also be checked during this scan, though it is important to note that not everything is detectable. If you agree to have the combined screening test for Down’s syndrome, Patau syndrome, and Edwards’ syndrome at this scan, you will have a blood test, and some fluid will be taken from the baby’s neck to measure for nuchal translucency. In babies with one of these chromosomal syndromes the measurement of that bubble of fluid tends to be increased. These two tests, combined with your age, are used to work out your baby’s chance of having Down’s syndrome, Patau syndrome, and Edwards’ syndrome. Results are usually received by post.

Can the screening test hurt my baby?

No, it won’t hurt your baby, but the information you receive may lead to offers for diagnostic tests that do carry a risk of miscarriage.

What if I don’t want to wait until eleven weeks for my first scan?

You may be able to have one earlier if you’re especially anxious, but, in general, if you want more flexibility around the timing and number of your pregnancy scans, it is best to seek private care.

What happens during an ultrasound scan?

Scans usually last 20 to 30 minutes and take place in a dimly lit room. You’ll be asked to arrive with a comfortably full bladder, which lifts the uterus up so the sonographer can see the baby better. The sonographer will ask you to lie on your back and expose your stomach. They’ll apply some gel so it’s easier to pass the probe backwards and forwards over your skin and see the baby. The sonographer may have to apply slight pressure during the scan to get the best views. This may be a little uncomfortable for you, but it won’t harm the baby. The ultrasound view of the baby can be impeded if mum has fibroids or the baby is in a difficult position.

What happens at the 20-week scan?

The 20-week scan, known as the anomaly scan, is an exciting one! By this stage, your baby is well developed and a good size for the checks that are part of this scan. The scan provides more detail than the dating scan. None of the screening tests harm the baby, but they won’t pick up every possible problem. You don’t have to have the scan or the tests if you do not want to; your consent will be required before they begin. The anatomy checks include the heart, the head, the lungs, the kidneys, the bladder, the spine, and the face.

Heart checks usually take the longest time to check, as the heart needs to be looked at in a number of ways. Please don’t worry if the sonographer is quiet or appears to be looking at images for a long time. As well as looking at the anatomy, the sonographer will also look at the baby’s growth, their environment, and the placenta. They’ll measure your baby’s head, waist, and leg bone. At the end, the results of the scan will be given to you verbally, and a copy of the report should be placed in your notes. The report will include your baby's measurements and the list of checks that were taken. In some cases, the way the baby is lying or the quality of the images means you need to come back.

If you appear to have a low-lying placenta, you may be asked back for another scan at around 32 weeks to make sure the placenta is not covering the neck of the womb.

In a small number of cases, an anomaly is spotted during the checks, and the sonographer may ask for a second opinion for a colleague. If something appears wrong, the sonographer will tell you, and you may be referred to a specialist.

If asked, the sonographer will usually tell you the baby’s gender at this scan. Even their opinion at this stage may not be completely accurate, as image quality may vary and the baby’s position can obscure things. Gender information will be given to you verbally.

Can I film my ultrasound scan?

NHS hospitals have rules against this, and private hospitals may have the same. Always check with your healthcare provider before attempting to film or record anything on their premises.

Can I bring people to my scans?

Yes, a partner, friend, or family member should be fine. As a lot of concentration is required for the sonographer’s work and sensitive information may be shared, it’s best not to bring your other children.

Can I have photos of my scans?

Photos can usually be printed for you on thermal paper during the scan. You can ask the sonographer about this.

We hope your pregnancy scans go well. For more information on what to expect during every week of pregnancy, take Unii’s Pregnancy Journey video course with Dr. Shree Datta.

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