After you have had your routine dating scan at around 12 weeks and then your anomaly scan at around 20 weeks, you may be referred for a third trimester scan growth scan. The third trimester growth scan basically does what it says on the tin and measures to see how well your baby is growing.
Why would I be referred for a growth scan?
During your antenatal appointments with your midwife, she or he may suggest a third-trimester growth if it is thought that your baby is any of the following;
- Smaller than expected for gestational age
- Larger than expected for gestational age
- It could be to check which way up you baby is perhaps head up or head down.
- Fluid levels it may feel like there is too much or not enough
These checks combined will enable you to have a measure of your baby's well-being.
What happens during the scan you ask?
During your growth scan you sonographer will do a number of measurements that may include
- Checking of the position of you baby.
- Checking the position of the placenta
- Measure that largest pool of fluid around your baby
- Measure the baby's head, abdominal circumference and the length of the femur (leg bone)
- If clinically indicated measure the flow of blood going through the cord and baby's body.
What if my baby is too small or too large?
If your baby is measured small it would be called Small for gestational age (SGA). This could be simple and just mean that your baby is naturally small for the number of weeks into your pregnancy. It could also mean that your baby is in average size range but has a lower weight. This could mean that your baby isn't quite getting enough nutrients and oxygen and it needs through the placenta. In these cases your doctors will perform regular growth checks over a period of time and recommend Doppler ultrasound scan to measure your baby's blood flow.
If you baby is larger than expected then it isn't normally a problem but if your baby is quite a lot larger then it may be a sign of gestational diabetes. Gestational diabetes occurs when there is too much glucose in your blood. It can lead to complications such as having to be induced or a c-section. Your doctor or midwife will simply book an appointment for a glucose tolerance test or GTT to test for gestational diabetes, but again, it could just mean that you have a large baby.
All of these checks have a purpose and offer healthcare professionals an insight into how your pregnancy is progressing and show them what care to give and how to manage your baby's delivery in the safest and best way possible.