It was revealed back in February that the rising rapper would be joining pop superstar Bruno Mars on the final, North American leg of his 24K Magic Tour. That news came a month after the two teamed up on a remix of Mars’s track “Finesse,” and a few months ahead of the release of Cardi B’s star-making debut album.

Now, the rapper, who recently gave birth, has announced via a lengthy, heartfelt Instagram post that she is pulling out of the tour, explaining, “I think I underestimated this whole mommy thing.”

“Not only am I just not ready physically, I’m not ready to leave my baby behind since the doctors explained it’s not healthy for her to be on the road,” she wrote.

She likewise thanked Mars for his support and understanding.

The run of North American shows at which Cardi B was previously set to appear kicks off on September 7 in Denver, running through four nights of shows in Los Angeles in late October.