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What does ‘intersex’ mean?
People born with intersex variations have physical characteristics that don't fit the usual definition of a female or male body.
The term 'intersex' refers to a wide spectrum of variations to genitals, hormones, chromosomes and/or reproductive organs.
Some people with intersex variations may, for example, have typical sexual characteristics of a female on the outside, but mostly male-typical anatomy on the inside. A person might be born without a uterus, or with a micropenis. A person's genitals might be ambiguous ('in between' the typical features of a male and female). These are just a few examples.
Intersex variation can also include 'mosaic genetics', which means a person has cells that have XX (female) chromosomes as well as XY (male) chromosomes. Or, they might have an atypical combination of chromosomes, such as XXY.
How common is intersex variation?
It’s difficult to say how prevalent intersex variations are since medical professionals don’t always agree on what counts as intersex. Also, many people are born with variations that don’t show up until puberty or adulthood.
However, intersex variation is a natural biological event that has been estimated to occur in about 17 in every 1,000 live births (or 1.7%).
What causes intersex variation?
In the first few weeks after conception, genitals in a fetus develop in the same way, regardless of whether the baby is a male or female. At week 7, the genitals start to develop in line with the sex of the fetus, under the influence of hormones.
An imbalance of hormones, or an inability of the fetus to respond to the hormones, can result in an intersex variation.
How is gender assigned in people with intersex variation?
It is recommended that a child be assigned a gender soon after birth, based on the gender they are most likely to identify with as they grow up. This does not involve surgery and is not to be confused with gender confirmation surgery (previously known as ‘gender reassignment’ ).
If you're a parent of an intersex child, it's OK to delay announcing the gender and name of your child until you are ready. For more information and support, visit Intersex Human Rights Australia.
Does intersex variation need treatment?
Being intersex is not a health issue in itself and is considered a normal biological event.
Unless a person needs urgent medical attention after birth or treatment for specific health concerns related to intersex variation, such as infertility, medical intervention is not normally necessary.
Surgery for intersex variation is not recommended (or even necessary) until a child is old enough to make an informed decision for themselves.
Children and adults with intersex variation, and their parents, may benefit from counselling and support.
Are people with intersex variation transgender?
Intersex variation is not the same as transgender, which is where a person identifies as a gender that is different from the biological sex they were assigned at birth.
An intersex person may identify as female, male or neither, straight, gay, lesbian, bisexual or asexual.
However, Australian research shows that people with intersex variation are more likely to be non-heterosexual than people in the general population. About half of people with intersex variation are heterosexual (straight).
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Last reviewed: December 2019