Caiff y prawf ei gynnig i fenywod sydd wedi manteisio ar y cynnig cychwynnol  o sgrinio ac y ceir bod eu risg yn uwch o safbwynt syndromau Down, Edward neu Patau.
The test will be offered to women who have taken up the initial offer of screening and are found to be at a higher chance of Down’s, Edward’s or Patau’s syndrome.