Scanning for your baby

When ultrasound technology is applied to pregnancy, it involves sending high-frequency sound waves into the uterus which rebound off the baby. From the echo created by the waves’ interactions with the baby, an image is formed that accurately shows the baby’s position and even their movements. By the various shades of the image the qualified sonographer can differentiate between hard tissues like bone and fluids such as the amniotic fluid encasing the baby. These fluids are coloured black due to not absorbing the echoes, providing a useful background on which to see the developing baby.

The process

The sonographer places gel on the mother’s abdomen and then moves a handheld transducer across the skin. This scans inside the uterus for images of the baby. There is no pain associated with the procedure aside from slight discomfort if the mother has a full bladder. In certain conditions, such as when the mother is overweight or the baby is too deep within the pelvis, the images can be unclear. A vaginal scan is used in these cases, which is gently slid in with lubrication and a safe cover, and will provide much clearer images in early pregnancy. Some women opt for a vaginal ultrasound regardless; it is a personal choice.

Uses of ultrasound

In addition to the momentous occasion of the parent(s) seeing their baby for the first time, which can be celebrated with a memento of the ultrasound image, there are also a whole host of important practical applications of the scan. Chief among these is a vital check on the baby’s development, and depending on the number of scans you have during pregnancy, different stages (first, second or third trimester) offer different opportunities to ensure the baby is growing normally. Common checks include:

• Examining the normalcy of developing organs,
• Calculating the baby’s growth rate over time,
• Diagnosing any abnormalities as early as possible,
• Determining the placenta’s location and how much amniotic fluid there is,
• Checking for a heartbeat.

Ultrasounds can also detect multiple pregnancies (e.g. twins, triplets), or an ectopic pregnancy, in which the embryo implants in the fallopian tube instead of the uterus. If the mother experiences bleeding, a scan can pinpoint the cause. A nuchal translucency scan assesses the risk of Down’s syndrome between 11 and 14 weeks.

Male or female

At some point, many parents choose to find out the sex of their baby with the assistance of ultrasound. This occurs during an existing appointment and is never the primary reason for the scan. It is also worth noting that in some cases it can be harder to determine the sex, particularly early on, and some hospitals do not give an opinion if they cannot be certain. The sonographer looks for indicators of sex, including a penis or labia, but factors like foetal position and abdominal wall thickness can interfere. However, much modern equipment can help to identify sex between 11 and 20 weeks into pregnancy.