Rihanna and her halftime show team was "very careful" not to reveal she was pregnant before the Super Bowl last weekend, the director of the show said this week. 

"She was very careful about who knew," Hamish Hamilton, who has directed the halftime show since 2010, told "Entertainment Tonight." "And we only knew, really, at the very latest stages. Her and her team carefully managed that, and we obviously also then carefully managed that."

The "Rude Boy" singer became the first pregnant woman to headline a halftime show when she appeared on a platform more than 60 feet above the field on Sunday cradling her baby bump.

"It's a very, very personal, joyous moment," Hamilton said of her pregnancy. "So, it's for her to tell the world, you know? So, not only were we obviously very mindful of the fact that she was pregnant, but we're also very mindful of this kind of a show hasn't been done before either." 

HOW A PREGNANT RIHANNA PULLED OFF HER HIGH-TECH SUPER BOWL HALFTIME SHOW

Rihanna performing

Rihanna and her halftime show team was "very careful" not to reveal she was pregnant before the Super Bowl last weekend, the director of the show said this week. (John W. McDonough / Sports Illustrated via Getty Images)

Hamilton called the show "ambitious" technically, adding that the production team had a "huge amount of respect for the endeavor that we were taking on."

Rihanna at an event

Rihanna announced she is expecting her second child during the Super Bowl halftime show. (Getty Images / File)

"I think, given the ambition of the idea, the kind of lunacy, almost, in some ways, of the idea, I think anybody who was going to kind of tell the world was like, 'You know what? Let me keep the secret,’" he added.

He said keeping Rihanna and the other performers safe during the high-flying show was their top priority.

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Rihanna and A$AP Rocky are seen filming a music video in the Bronx

Rihanna and A$AP Rocky already share a son together. (Raymond Hall / GC Images)

"There were never any times when we were putting anybody in danger, but there were a lot of times when we needed to stop, evaluate the safety and then carry on," he said.

He said the technical aspects would be ambitious in a Broadway show "where you've got months and months to set it up ... [but] this is a Super Bowl. I mean, you've got eight minutes to get all that stuff out. Check it, safety check it, make sure it's cool, deploy it, and then fly her up. It was ridiculously ambitious."

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Ultimately, the "Umbrella" singer’s show went off without a hitch, and she surprised the world with her baby news.