Determination of sex

Determination of sex is a process by which scientists and medical professionals determine the biological sex of a person or other animal using genetics and biological sexual traits. It is not to be confused with sex assignment which is a more recent colloquial term that allows for the use of non-sexual or non-genetic traits to define a person's sex.

Primary sex determination
Primary sex determination is the determination of the gonads. In mammals, including humans, primary sex determination is strictly chromosomal and is not usually influenced by the environment. Hence, the gonads are usually indicative of the biological sex. This direct correlation allows scientists and medical professionals the option to determine biological sex using gonads. When the purpose is to distinguish male vs. female in animals, this is sexing.

Genetic sequencing is a second way for a scientist to determine biological sex in both humans and animals (distinct from sexing). It became widely available and popular at the turn of the century. Genetic sequencing also allows for the determination of rare genetic events when the y chromosome is incomplete and a male animal has female gonads.

Prenatal determination
Prenatal sex determination is prenatal testing for discerning the sex of a person or other animal before birth. Techniques include:
 * Cell-free fetal DNA testing, wherein a venipuncture is performed on the mother to analyze the small amount of fetal DNA that can be found within it.
 * Chorionic villus sampling (CVS) and amniocentesis, which are two rather invasive testing procedures.
 * Obstetric ultrasonography, either transvaginally or transabdominally, which can check for the sagittal sign as a marker of fetal sex.

Use in medicine and science
Currently, the determination of sex by physicians at the time of birth is used in medicine for health care purposes and the standard of care in medicine is biological sex. However this has become controversial and could change in the future.

History
In writing, the term "Determination of sex" peaked in usage around 1910. The term "sex determination" increased in usage after 1900. In the 1960 and early 70's the term "sex assignment" came into prominent use as a colloquially word for "determination of sex" and "sex determination". "Sex assignment" did not occur in writting prior to the 1940's.