Josh Adams was suspended from the Six Nations squad after Wales management became aware of a gender reveal gathering he held with family.
Adams and partner Georgia Davies went to a relative's home on Sunday as they discovered they are expecting a baby girl in July.
A video was posted on a her public Instagram page, which has now been made private, showing the couple pulling a party popper-style tube, with pink confetti revealing the gender. Loud cheers and screams can be heard on the video from other people in the house.
The couple are standing in front of a giant banner emblazoned with the words 'boy or girl'.
Wales did not become aware of the gathering until after Adams had trained on Tuesday, when team manager Martyn Williams informed Wayne Pivac what had happened.
Wales' players had been allowed to leave camp over the weekend but are under strict instructions to follow Covid-19 lockdown rules. Players and their families were given advice on what they could and could not do ahead of the tournament.
"It came to our attention yesterday after training," Pivac said.
"As soon as it came to our attention, we spoke to the player, he was up front and honest. We moved pretty swiftly to do what we could. We wanted to put it out there as we want to be seen doing our bit as leaders and role models."
Pivac added: "It was at a family member’s home. It was a very quiet celebration. As far as I’m aware, there was no alcohol involved. It was a celebration in terms of the family was getting together for something special that has happened and we will leave that part to the family."
Adams apologised for his behaviour, saying in a statement: "I would like to apologise unreservedly," said the winger.
"When out of camp, at the weekend, I made an error of judgement. I attended a small gathering of immediate family to celebrate a family milestone.
"It was wrong to do this. I'm aware that everyone needs to follow the rules and being in the public eye I have a responsibility to lead by example and I've fallen short on this occasion.
"I'd like to apologise to my teammates and to our supporters for my mistake."
He is now suspended for Wales' opening two Six Nations matches against Ireland and Scotland.
