Kimora Lee Simmons Expecting Fourth Child

There’s another baby on the way for Kimora Lee Simmons.

The model and designer, 39, is expecting her fourth child, PEOPLE confirms.

Already mom to daughters Ming, 14, and Aoki, 12, with Russell Simmons, and 5-year-old son Kenzo, with Djimon Hounsou, this will be Simmons’s first child with husband Tim Leissner, whom she married in February.

“It’s true. Pregnant, happy – so far so good,” a source tells PEOPLE. “[She’s] cautiously optimistic. [The] girls are ecstatic.”

The New York Post‘s Page Six was first to report the news, adding that Simmons is about four months along.