Marker pen drawing on a calendar
Louise Broadbridge
Louise Broadbridge

12 week scan – what to expect 

Often referred to as the 12 week scan, the dating scan is an ultrasound examination which is carried out between 10 and 14 weeks of pregnancy. For most women, this will be the first scan of their pregnancy.

Why do I need a 12 week scan? 

One of the main purposes of the 12 week scan is to check how the pregnancy is progressing and estimate a due date. Up until the first scan, your estimated due date will be based on the date of your last period.

However, for some women accurately dating a pregnancy in this way can be difficult as their periods may be irregular, they may not remember when their last period was or they may have continued to experience some bleeding in the early stages of their pregnancy. The estimated date of delivery (EDD) given as a result of the scan is much more accurate than working out how pregnant you are based on your menstrual cycle.

As well as dating the pregnancy, the 12 week scan is an opportunity to look at how the baby is developing and whether they are growing in the right place. If you are expecting more than one baby, you will usually find this out during the dating scan – unless you already had a scan in early pregnancy for medical reasons.

The ultrasound might be able to detect some health issues like spina bifida and will reveal the position of the placenta. If you have agreed to screening for Down’s Syndrome, a nuchal translucency scan will be carried out during the ultrasound appointment. 

The sonographer will measure the fluid at the back of your baby’s neck. This measurement, along with a blood test, will then be used to calculate the chance that your baby might have Down’s Syndrome.

For many people, the 12 week scan is an exciting time as it is their first opportunity to see their baby and it can help their pregnancy to feel more real. However, it can also be a worrying time, especially for those who have a history of miscarriages or pregnancy complications.

What happens during the 12 week scan?  

Your dating scan appointment will normally have been arranged by your midwife or doctor and it will usually take place at your local hospital, although some areas may also have ultrasound facilities at health centres.

The scan itself is carried out by a sonographer and will typically take around 20 minutes. You may be asked to drink plenty of water before the scan so you have a full bladder as this makes it easier for the sonographer to get a clear image.

The scan itself is completely painless, although you may feel a little uncomfortable if you have a very full bladder so try not to overdo it too much with drinking water beforehand. It works by using sound waves to form an image of your womb and your developing baby.

When you arrive for your scan, you will usually be asked to check in with the reception staff so they know you have arrived for your appointment. When it is your turn to be scanned, you will be called into a dimly lit room and asked to lie on your back on a coach.

You will need to reveal your stomach so it’s a good idea to wear clothes which make this easy. The sonographer will then squirt some warm gel onto your stomach – this ultrasound gel forms a bond between the probe and your skin to make sure the scan is effective.

During the scan, the sonographer will move the probe around your stomach and may need to apply some pressure at various points to get a good image. The sonographer will look at your baby on their screen and will take measurements to check their development.

There may be points during the scan where you are not able to see your baby as the sonographer will need to keep the screen facing them until the examination is complete. Once they have carried out all the necessary checks, they will usually turn the screen so you can get a view of your little one.

In some hospitals, they may also be able to put the images onto a larger screen facing you. You will then usually be given an opportunity to have a picture taken of your baby which you can take home and keep.

Check what the policy is in the hospital where your appointment is taking place as it does vary. Some hospitals charge a fee per scan picture and will allow you to buy additional copies. Other hospitals may allow you to have one scan picture for free.

Having a picture taken is optional and is not part of the medical examination so remember to ask if this is important to you.

Sometimes your scan might take longer than 20 minutes if your baby is in a position which makes it challenging for the sonographer to get a clear view. Sometimes, you may be asked to return at another time so the scan can be repeated, although this is not common.

If the scan is unclear or reveals anything concerning, the sonographer may ask a doctor or another member of staff to come into the room and give their opinion. If there are any concerns, someone should explain the situation to you and you may be offered some additional tests.

Is an ultrasound scan safe?

There are no known risks to having an ultrasound scan but as with any medical procedure or examination, it is optional. If you are unsure whether you want to have a scan, talk to your midwife about your concerns.

Can I bring someone with me to the scan? 

You will usually be able to bring someone with you to your 12 week scan but do check what your hospital’s policy is in advance. Some hospitals will only allow one other person to be in the room with you, while others may have slightly more relaxed rules.

What will happen after the scan?

In the majority of cases, the scan will show that everything is developing normally and you will told your estimated delivery date, which may be different to the due date you already had. You will usually be able to leave your appointment after the scan unless you are due to see a midwife or consultant as part of your arranged antenatal care.

If the sonographer detected a problem or found there was more than one baby, you may be asked to stay to speak to a consultant and additional appointments might be arranged. If you have a low-lying placenta, you will usually simply be told by the sonographer and it will be recorded in your maternity notes so it can be checked again at your 20 week scan.

Occasionally, the 12 week scan may reveal that the baby has died in the womb. If this happens, you will be given some advice on what happens next.

Will I find out my baby’s sex during the 12 week scan?

The 12 week or dating scan does not involve checking whether the baby is a boy or girl. If you want to find out your baby’s sex during your pregnancy, you may be able to find this out during your 20 week scan or you can arrange to have a private gender scan from 16 weeks of pregnancy, although you will need to arrange and pay for this yourself.

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