Actress Lacey Chabert has become a first-time mother.

The Mean Girls star and her husband Dave Nehdar welcomed a baby girl on 1 September (16), and the new mom announced the news in a sweet Instagram post a week later on Thursday (08Sep16).

Alongside a photo of her little one wrapped in a pink blanket, she wrote, "#TBT (Throwback Thursday) to the best day of my life. One week ago I became a mom to this precious angel. Julia Mimi Bella."

"Julia, you are my heart's deepest dream come true," she continued. "I love you more than I could ever say. Welcome to this big beautiful world sweet girl!"

The 33-year-old wed Nehdar in 2013 and revealed her pregnancy in February (16).