I think the 'gender reveal' is something different from what you are thinking.
during a gender reveal party that was held to show the gender of his wife's expected baby
Personally, I've never heard of having a party to announce if an expected baby is a boy or girl, but I'm not surprised they happen. I initially figured they were talking about that silly 'gender' crap in the news of late as well, but apparently they were normals, not freakazoids.
These "parties" have been going on for at least the past 5 years; perhaps a bit longer. I find them dumb and thankfully, they aren't as universal as one might assume that they they are.
The trannies and queers have "coming out parties", which is a debasement of the use of that term for girls reaching a marriageable age and being "introduced to society".