Donald was born to John and Helen Donald in 1910. His father was a doctor and his mother was a concert pianist. His sister Alison was to be a leading headteacher.
Whilst Professor of Midwifery at Glasgow University, he first explored the use of ultrasound in the 1950s after seeing it used in the Glasgow shipyards to look for flaws in metallurgy. He became Regius Professor of Midwifery in 1955. His article Investigation of Abdominal Masses by Pulsed Ultrasound, published 7 June 1958 in the medical journal The Lancet, was one of the defining publications in the field. Ultrasound has become an important aid to diagnosing fetal progress during pregnancy.