What name is given to a party held before birth to reveal a baby's expected sex?

A party held before birth to reveal a baby’s expected sex is called a gender-reveal party.

In the familiar format, the parents or a designated person uses a cake, box, balloons, colored powder, or another planned device to disclose a hidden color or message. Blue and pink are often used, although families may choose different themes. The event is commonly separate from a baby shower, though the two may be combined.

The term is widely used in popular culture, but it is technically imprecise: a prenatal test can indicate fetal sex, while gender concerns identity and social roles. For that reason, some families and commentators prefer phrases such as “sex reveal party” or simply “baby announcement.”

The celebration is a modern tradition rather than an ancient rite. It became especially visible through blogs, social media, and online videos during the 2000s and 2010s.