Certain sounds become popular. For instance, girls' names beginning or featuring 'J' were quite popular in the 70s - Jackie, Julie etc. Over time, as parents were on the lookout for a fresher more original sound, this gave way to 'K' names or those featuring a hard 'C' - Kayleigh, Kelly, Chrissy, Claire. Currently, 'V' is a trendy sound: Violet, Ivy, Savannah, Evie, Ava etc. The letter 'I' also crops up in a lot of names right now - Isabella, Isla, Olivia, Ivy. At some point these letters will cease to sound fresh and parents will move on to newer, fresher sounds.
Parents always want their kids to have a name which is nice but a bit different. People are often concerned about popularity because they don't want their child to have a 'boring' name. Our own children won't find the names Ivy and Olivia a little bit fresh and different. By the time they are parents, all these names will have connotations. The name Ivy will be the name of their partner's ex-girlfriend. Olivia will be the name of her class bully. Meanwhile, Laura, Claire and Sarah are the names of their parents' generation - middle-aged and boring. Names like Carol, Susan and Linda are old grandparent names, associated with nursing homes and walking sticks.
But Joan? Margaret? Pauline? These names will honour great-grandmothers. They feature consonants and have a no-nonsense style, contrasting with the longer, frillier styles of the 2010s and 2020s. They sound fresh to a new generation and so the cycle begins again.
Naming trends are more apparent in girls and fashions change more quickly. Boys' names have tended to be more conservative and boys are more likely to be named after their fathers than girls are their mothers. This may be starting to change, but it will take time.