This is such bollocks I don't know where to start.
Generally the more vulnerable the pregnancy, the more scans are given, so the most at risk get the most scans and there is no link whatsoever with developmental issues.
The sonographer sounds quite unhinged, to be honest.
Was it a private scanner who said this to you, I really can't believe a trained professional would say it (you don't need any qualifications to work as a sonographer in a private scanning clinic)
To be honest I think it was more the anxiety, I think she was having a passive aggressive dig at you. eg oh you are having a scan because you are anxious, but doing so might be making you worse not better.
Because of my history I am very anxious in this pregnancy and most docs I have met take the attitude that being anxious is a normal reaction to what I have been through and shows my mental health is intact iyswim, but I have met a couple of lesser trained, lesser skilled healthcare workers, real jobsworths, who seem to think I shouldn't be and it is OK for them to pass comment, make subtle digs etc
I have actually had a specific conversation about whether scanning is ok in a meeting which consisted of me, DH, a professor of obstetrics, a consultant specialising in prematurity, a midwife sonographer, a bereavement midwife and an EPU nurse, all of whom were working in a major teaching hospital which is a leading centre of research into the causes of miscarriage and fetal abnormality, so frankly, they have forgotten more than that sonographer you met will ever know.
So far this pregnancy I've had
6 weeks internal scan to check in right place
8 weeks internal growth scan
10 weeks external growth scan
12 weeks dating scan
14 weeks internal placental check scan
16 weeks internal placental check scan
16 weeks external growth scan
18 weeks internal placental check scan
20 week external abnormality scan
22 week internal placenta check scan
22 week external abnormality scan (they wanted another look at the heart after the 20 week one)
24 week internal placenta check scan
All of these scans have been at a NHS teaching hospital and ordered by the consultant. Hope this helps to reassure you.