The Ericsson method is an assisted reproductive technology for sex selection, used before implantation.
In this method, sperm that will give rise to male versus female children are separated by moving at different speeds through a protein solution.
[3] The Ericsson method is based on the belief that X-sperm swim slower than Y-sperm.
Sperm are placed atop a "column" of increasingly thicker layers of albumin, and allowed to swim down into the solution.
These references represent the initial scientific research, the concepts behind altering the sex ratio, the clinical results and the social and demographic history of people who elect to use this technology for a wanted sex selected child.