In 2012, the most popular names for girls all ended in -a, according to parenting website BabyCenter.com. 

The popular girls' names in 2012: Sophia, Emma, Olivia, Isabella and Ava.

For boys, names include: Aiden, Ethan, Liam, Mason and Jacob. 

"Names from two generations back are meaningful and retro and have a cool factor," BabyCenter.com's Linda Murray told USA Today.

BabyCenter.com released the list last week (and updates it frequently), just days before the Duke and Duchess of Cambridge announced they are expecting their first Royal baby. 

According to BabyCenter.com, Catherine is not in the top 100 girls' names in 2012, but William is number 12 on the boys' list so far. Another Royal saw his name skyrocket in popularity: The name Harry is up "a whopping 57 percent" according to BabyCenter.com. Pippa is up 35 percent.

Massachusetts' own state list, according Social Security Online, is not yet available. But in 2011, the top five baby girl names in the Commonwealth were Sophia, Olivia, Isabella, Emma, and Ava; and the top five baby boy names were William, Benjamin, Jacob, Michael, and Ryan.

CNN reports that a bookie taking bets on the child's name says the most popular so far: Frances and John as the favorites for the baby's name, at 9-to-1, with Charles, Victoria and George at 10-to-1.

Do your kids' names show up on this list? Do you have a guess on the Royal baby's name? Let us know in the comments.