Blake Lively Glows in First Instagram Portrait Since Giving Birth to Baby Daughter: Photo Shoot Details

The one. The only. @mariotestino ????????????????????????????????????

A photo posted by Blake Lively (@blakelively) on Feb 4, 2015 at 4:13pm PST

Glow baby glow! Blake Lively shared a photo of herself on Instagram for the first time since welcoming her daughter with Ryan Reynolds last December. 

In the stunning snapshot taken with legendary fashion photographer Mario Testino, the new mom beams and looks elated as she flashes her pearly whites for the lens. Lively, 27, and Testino coordinate outfits, with the star wearing a black number embellished with jewels and the photog in a matching blazer. "The one. The only. @mariotestino," the Gossip Girl actress wrote alongside the bright snap posted Wednesday, Feb. 4.

Testino, who's worked with Lively on numerous occasions, also gushed about the Preserve founder on his Instagram. "GREAT DAY WITH THE GORGEOUS @BLAKELIVELY," Testino, 60, wrote alongside the same snap. Lively last posed for Testino in a gorgeous Vogue cover story which debuted in the magazine's August 2014 issue in conjunction with the launch of her lifestyle website Preserve.

While many speculated that the shoot was again for Vogue, sources reveal to Us Weekly that Lively was working with Testino on an upcoming spread for Allure.

Lively revealed that she was expecting her first child last October on Preserve. Us Weekly confirmed that she and Reynolds welcomed their daughter just before the New Year. "The baby came early," a source told Us at the time, "but everyone is happy and healthy."

As for first-time parenthood? Lively's hunky husband told David Letterman on Wednesday that welcoming his baby girl (name still a mystery) has made him fall more deeply in love with his wife.

"It's amazing," Reynolds gushed of life with his new family. "I'm not one for vomiting declarations of sentiment out across the airwaves, but when we had that baby, I fell more in love with my wife than I'd ever been in my entire life. I couldn't even believe it."

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