Children's Hospital Colorado

Ambiguous Genitalia (Atypical Genitalia)

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What is ambiguous genitalia? 

Ambiguous genitalia is a rare condition where a baby is born with external genitalia that aren’t clearly defined as male or female. This may include external genitalia that:

  • Don’t match the baby’s genetic sex or internal sex organs
  • Have features of both male and female genitals
  • Haven’t fully developed

Ambiguous genitalia is also called atypical genitalia. It’s considered a disorder or difference of sex development (DSD), a group of conditions (previously called “intersex”) that occur when biological sex and external genitalia don’t match. Differences of sex development affect about one in every 2,000 babies.

What causes ambiguous genitalia?

Sex development begins early during pregnancy and continues throughout life. Sex development is a complex process influenced by a number of factors, including chromosomes and hormone production. Variations in these processes can result in differences in the internal sex organs and external genitalia. Typically, a baby’s sex organs develop in three steps:

  1. When the sperm fertilizes the egg, the male parent gives an X or Y chromosome, and the female parent gives an X chromosome.
  2. The fetus develops sex organs, either ovaries or testes.
  3. Inner and external genitalia also develop, usually shaped by hormones from the testes or ovaries.

Ambiguous genitalia form when any of these steps are disrupted. Disruptions can occur because of:

  • Chromosomal problems, such as an extra or missing chromosome
  • Gene changes (mutations)
  • Lack of or overexposure to male hormones in utero

Who gets ambiguous genitalia?

Your family history can increase the chances of having a baby with ambiguous genitalia. Risk factors include a family history of:

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