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Oh my, Michah!

Sarah Drew gave birth to son Micah Emmanuel Lanfer Wednesday evening in Los Angeles, a rep for the Grey's Anatomy actress, 31, tells Us Weekly.

Weighing in at 7 lbs, 4 oz and measuring 19 inches long, Michah is the first child for Drew and her husband Peter Lanfer.

The then-pregnant star told Us last year that her Grey's costars -- many moms among them! -- had been "incredibly helpful" helping her and Lanfer prep for baby.

"I got great advice about nausea from Ellen Pompeo because I am still dealing with nausea, which is no fun," Drew said. "She's a wealth of information: she's done all the research and looked into every possible way of doing things."

"I've gotten some great advice from Jessica Capshaw, especially about the brand of Pampers I'm supposed to be using. But I'm like, 'Dude, I have some time.' And I had great advice from Chyler Leigh about breastfeeding."

Hubby Lanfer was "literally a dream," she gushed to Us. "He's become super protective of my energy level and time," she added of Lanfer, whom she wed in 2002. "He's been amazing. I can't ask for a better partner."