Jess,
Congratulations on your baby girl. I hope she is doing well.
You are correct that Right is less common than Left. We are not exactly sure why that is but we think it has to do with how the three sheets of muscle come together to form the diaphragm in early fetal development. This convergence of the muscles is more often disrupted on the left side.
We also have seen that children with a Right sided do not necessarily have a worse prognosis but may need more intervention than children with a Left sided hernia. In our follow up of 250 children with a CDH, we found that children with a Right sided CDH needed ECMO more often than L sided CDH but did not over all have a worse outcome than children with a Left sided CDH.

We have seen families with members with both Left sided and Right sided CDHs which leads us to believe that at least some of the genetic causes are the same but we also suspect that some genetic causes only cause a Right sided CDH and some only cause a Left sided CDH. We are working to answer all of these questions.

Best,
Julia