In humans, sex determination is the process that determines the biological sex of an offspring and, as a result, the sexual characteristics that they will develop. Humans typically develop as either male or female, primarily depending on the combination of sex chromosomes that they inherit from their parents. The human sex chromosomes, called X and Y, are structures in human cells made up of tightly bound deoxyribonucleic acid, or DNA, and proteins. Those are molecules that contain the instructions for the development and functioning of all life forms, including the development of physical traits and body parts that correspond with each biological sex. Humans who inherit two X chromosomes typically develop as females, while humans with one X and one Y chromosome typically develop as males. Sex determination is the beginning of the development of many characteristics that influence how a human looks and functions as well as the societal expectations that other humans have for each other.

In 1974, the United States Supreme Court decided in a six-to-three decision in Geduldig v. Aiello (1974), hereafter Geduldig, that pregnancy-related disabilities could be excluded from state-run disability insurance programs and that discrimination based on pregnancy did not constitute sex discrimination. Carolyn Aiello, a woman denied disability benefits in California since her disability was pregnancy-related, and three other women facing similar discrimination, sued Dwight Geduldig, director of the California Department of Human Resources Development for violating the equal protection clause of the Fourteenth Amendment. Under California’s Unemployment Insurance Code at the time, conditions or disabilities that arise from or are related to a pregnancy were excluded from coverage. Aiello and the other women argued that by not insuring pregnancy-related disabilities, the state was unfairly discriminating against women. Geduldig detached pregnancy discrimination from the injustices uniquely faced by women by determining that civil rights law did not apply to pregnancy status, exacerbating the inequality women in the United States face in employment, education, and economic opportunity.