Mark Ronson and Grace Gummer welcomed their second child, a daughter, last week, Page Six has learned.

The megaproducer is being extra careful as new dad.

On Wednesday, he made a brief appearance at his mom Ann Dexter-Jones’ birthday party — hosted at his future brother-in-law, chef Daniel Humm’s cocktail lounge, Clemente Bar — but wore a mask the whole time.

A source told us the “Uptown Funk” artist wore the mask because, “he and Grace had a baby five days ago.”

Ronson’s newly engaged stepsister, Annabelle Dexter-Jones, and her fiancé, Humm, hosted the shindig –and his other sister, Samantha Ronson, and stepdad, Foreigner founder Mick Jones, both made an appearance.

New mom Gummer, the daughter of Meryl Streep, did not attend the party.

The Grammy-winning producer — who just co-produced “SNL50: The Homecoming Concert” with Lorne Michaels — and the “Let the Right One In” actress publicly revealed the pregnancy in December at their annual holiday party at Pebble Bar in NYC, when Gummer debuted her bump in a red fitted t-shirt dress on Instagram.

The pair hit the dance floor at the bash with their A-list pals, including Aziz Ansari, Dianna Agron, Chris Rock, Pebble Bar co-owner Carlos Quirarte and Justin Theroux, who co-hosted the event.

The couple started dating in 2020 and tied the knot one year later, in August, 2021. Red seems to be Gummer’s go-to color to reveal her expectant mom status. She debuted her first bump sporting a red dress at W magazine’s 50th anniversary party in October, 2022.

Ronson, 49, and Gummer, 38, are also parents to daughter, Ruthie, 2.