The 28-year-old model is expecting her second child, but the baby will be the first for the reality TV star.
Chyna insists she is not worried about how he will take to parenthood, reported Contactmusic.
"He's a genuinely loving person... Rob has all the qualities of a good father... He'll be straight," she said.
The couple announced their engagement in April and revealed that they are expecting their first child together, last month.
It has also been confirmed that the parents-to-be are filming a "Keeping Up With the Kardashians" new six-episode document series, which will air later this year.