Upon her father's foreign posting as the Thai ambassador to Italy, Xavier entered Clark's Commercial College in London.
She then passed matriculation and entered the London School of Medicine for Women and the Royal Free Hospital.
[1] Following her father's death, Xavier returned to Thailand in 1924 and became an obstetrician and worked for the Thai Red Cross Society, King Chulalongkorn Memorial Hospital, and the medical facility in Bang Rak District under the Ministry of Public Health.
As the Bang Rak medical facility was for treatment of sexually-transmitted diseases, many of her patients were impoverished sex workers, whom she would treat free of charge.
She opted to breastfeed the children herself, despite the fact that a woman of her status during that time would have employed the help of a wet nurse.