Ultrasound scans

Seeing your baby for the first time can be very exciting, even if it looks like a blob with a big head!

You’ll probably see your baby wriggling around, and if the sonographer shows you its heart beating you’ll be surprised at how fast it is (roughly 120-160 beats per minute compared with yours, which is around 100 beats per minute).

It’s your choice as to whether you have an ultrasound scan and you shouldn’t feel pressured to do so. Most parents relish the opportunity to see their baby on the screen in front of them – especially dads, for whom pregnancy can be a fairly abstract notion since they can’t feel the baby inside them!

You may worry if ultrasound scans are safe for your unborn baby. Numerous studies haven’t indicated any harmful effects, but the American College of Obstetricians and Gynecologists recommends scans be given only when medically necessary. Scans bounce high-frequency sound waves off solid objects to form a picture on the screen – they’re non-invasive and don’t expose your baby (or you) to any radiation. They’re not infallible though – especially when it comes to revealing whether your baby is a boy or girl. Don’t paint the nursery pink until you’re holding the living proof in you arms! Their accuracy depends on the quality of the equipment, the length of time the scan lasts, the sonographer’s experience and how your baby is lying in the uterus.

When will I have a scan?

Occasionally you may be offered a dating scan in your first trimester (weeks 0-12) if you’re unsure of your dates and are at risk of having a baby with an abnormality, since the accuracy of screening and diagnostic tests depends on when they’re performed. You may also have an early scan if there are any concerns about your pregnancy (for example, if you’ve experienced any bleeding or you conceived via IVF).

For most moms-to-be, their first scan is the nuchal translucency scan, which forms part of their first trimester screen between weeks 11 and 13. It measures an area of fluid behind the baby’s neck that has been linked with chromosomal disorders such as Down syndrome.

You’ll have a second ultrasound scan between 16 and 20 weeks, when the sonographer will check that your baby is developing normally, particularly if you had a positive result on any of your screening tests. This scan is highly effective at picking up problems – neural tube defects such as spina bifida, kidney problems, limb abnormalities and defects of the abdominal wall are all likely to be seen if they exist. Other conditions, such as congenital heart problems and hydrocephalus (excess fluid on the brain) may also be diagnosed at this stage. Keep in mind though that both scans are screening tests and you’d need to have a diagnostic test such as chorionic villus sampling (CVS) or amniocentisis for a definite diagnosis.

The information in this feature is intended for educational purposes only. If you have any concerns about your health, the health of your child or the health of someone you know, please consult with a doctor or other healthcare professional.