Poliksena Nestorovna Shishkina-Iavein was born in April 1875 in Nikolaev, Russian Empire (now Mykolaiv, Ukraine).

She married a professor at the Medical-Surgical Academy, Georgi Iulievich Iavein, in 1900 while studying at the St Petersburg Women's Medical Institute.

During World War I, Shishkina-Iavein taught medical courses, worked in a hospital for soldiers and helped to organize public canteens and women's shelters.

The family left St Petersburg after the October Revolution of 1917 and moved to newly independent Estonia, but Shishkina-Iavein was not allowed to practice medicine there.

Shishkina-Iavein wrote for the magazine Jus Suffragi, the official journal of the International Woman Suffrage Alliance, and had a lot of contacts with foreign feminists.