Justin Trudeau welcomes baby son, Hadrian

The Trudeaus are welcoming another member to their family today.

Liberal Leader Justin Trudeau announced the arrival of Hadrian, weighing in at 8 pounds and 3 ounces, on Twitter Friday morning.

• WATCH: Archival footage of Justin Trudeau as a newborn

"Welcome to the world, little Hadrian. 8lbs 3oz, Sophie is wonderful, Xavier and Ella-Grace couldnt be prouder," he tweeted.

Hadrian is the third child for Trudeau and his wife, Sophie Gregoire.

He arrives hot on the heels of the Liberal policy convention in Montreal, where a very pregnant Gregoire appeared via Skype from the couple's hometo address the audience in Trudeau's opening speech.

"I know you wanted to be here," Trudeau said to his wife from the stage. "Is there anything you want to tell people?"

"Well, for very obvious reasons," Gregoire responded, standing up in profile in front of the camera to show her pregnant belly, "I can't join you tonight physically, but it's an honour for me to be joining in like this."

Some co-sleeping

During one of Trudeau's final appearances at the convention, CBC producer Chris Rands threw him a question asking what colour the couple will decide to paint their nursery.

"We don't know yet," Trudeau replied. "It's in browns and greens right now. We'll find out in a couple of weeks."

Rands also asked about where the baby would sleep.

"We're probably going to do some co-sleeping, actually," Trudeau said.

Co-sleeping is when infants share a bed with their parents.

The birth came on the30thanniversary of the resignation of Trudeau's father, Pierre, as prime minister. He resigned on Feb. 29, 1984 a leap year.