21/03/2023
Did you hear the latest episode of the great birth rebellion podcast on ‘small babies, big babies’ where myself and discussed the challenges of growth scans for clinical decision making?
We shared from the research (which you can access if you are on the podcast mailing list) that ultrasounds to assess the size of your baby are ‘accurate’ 70% of the time, but the acceptable ‘accuracy’ and margin of error is +/- 10%…
So, if they tell you your baby is 4000gms it could actually be 4400gms or 3600gms… and that is the accepted margin of error on growth scans. The other 30% of the time, they are even less accurate.
The clincher is if you choose to be induced or have a cesarean section because of the suspected size of your baby, you won’t know how accurate your scan was until your baby is out.
The 2023 Cochrane review on induction of labour for suspected macrosomic (large) babies says that because of the inaccurate nature of growth ultrasounds, we shouldn’t be using them to make decisions about induction for suspected large babies… because, doesn’t matter how good we think we are, we are still too crap at determining foetal size with ultrasound to start using it as a tool to recommend induction.
Just listen to the episode.
