An early advocate for the use of anaesthetic during childbirth, Ellis-Crowther operated the Waitemata Obstetric Hospital in Glen Eden, West Auckland from 1945 to 1954.

[3] Her husband died in a truck accident in 1932, leading Ellis-Crowther to buy an orchard in Glen Eden, West Auckland.

[2][1] In 1938, Ellis-Crowther wrote an article in feminist magazine Woman To-day, arguing that the use of pain relief during childbirth was a human right.

[6] Ellis-Crowther's views on anaesthetics were opposed by Grantly Dick-Read and other male doctors, who were advocating for anaesthesia-free natural childbirth.

[7] When she began to retire in the 1970s, Ellis-Crowther convinced midwives Joan Donley and Carolyn Young to leave hospitals and take over from her, to continue providing home birth services.