Cardi B was pregnant with Offset’s baby, yes. She revealed it as an official thing as part of a Saturday Night Live sketch back in April, bump proudly shown off in a tight white dress. That was, as of when this answer was written, six months ago. The baby was officially welcomed in July, so they are proud parents. There are rumors that the couple plans to have another baby to give Kulture, the July baby, a sibling, but nothing has been confirmed as of October 2018.
Cardi B and Offset are a married couple, both relevant names in hip hop music today. It makes sense that she would have had her husband’s baby. That doesn’t mean there won’t be problems down the road, but for now, it seems the couple is happy.