Edyta Mordel, 33, went to the High Court in London suing the NHS for 'wrongful birth', saying she would have aborted the baby is she'd known he had Down's syndrome.
Mordel is suing for compensation for the increased financial burden of caring for her boy, and its impact on her ability to work.
Her son Aleksander is now four years old and although Mordel says she's devoted to him, she wouldn't have had him if she'd known.
When she fell pregnant in 2014, Mordel claims she told a midwife at her first appointment that she'd like to be screened for Down's syndrome.
Then when she went for her 12-week scan, Mordel says she believed a test had been carried out that gave her the all-clear. However, medical records show ‘Down’s screening declined’ and the test wasn't performed.
'I spoke with the midwife about Down’s syndrome screening. I had informed myself. I watched a lot of videos and read about screening,' she told the High Court.
‘I knew from the start that I would agree on the Down’s syndrome screening and I would not make any other decision.’
Her barrister, Clodagh Bradley QC, said: ‘Miss Mordel would have been offered an abortion and she and her partner, Aleksander’s father Lukasz Cieciura, agreed they would have terminated the pregnancy.'
After giving birth in January 2015, Mordel's medical notes show she was very 'upset and angry' that her baby had Down's syndrome.
Lawyer Michael de Navarro QC, for the NHS hospital trust, believes she changed her mind about having the test in the month between seeing the midwife and having the scan.
He said: 'Not only did her copy of the handheld notes contain the scan report saying that Down’s screening had been declined, but she must have realised that she had never had the result of screening which she had been told to expect.’
Mr de Navarro said it was ‘inconceivable’ that the sonographer would have written that screening was declined if that was not true.
The hearing continues.