I've been researching the safety/risks and according to WHO and midwifery today, these are only meant to be offered to high risk mums or those where a problem is suspected, although they are often offered routinely.
The research I've looked at states there is no benefit in routine ultrasound scans for low risk pregnancies and that there is even some evidence that the radiation from ultrasound can be harmful to the foetus, and certainly not enough research has been done to be sure that ultrasound is entirely safe for foetuses.
I am summarising but this is broadly what I found out. Not wishing to scare anyone about scans, but I believe in making an informed choice rather than going along the NHS conveyor belt without questioning anything!
I had 12 week and 20 week scans with my first baby and the 20 week scan was not a pleasant experience and very uncomfortable.
I am in a different area this time so not sure what I will be offered in the way of scans, but I am 35 so probably considered 'high risk'.
I'd be interested to hear of anyone's experiences if they chose not to have the scans they were offered.