More than 200 studios across the UK now sell ultrasound scans, with hundreds of thousands being carried out each year.
But the BBC has uncovered evidence of women not being told about serious conditions and abnormalities.
The Care Quality Commission says there is good quality care in the industry but it has a "growing concern".
Presented by Rianna Croxford
Produced and Directed by Noel Titheradge
Filmed and Edited by Adam Walker
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