Top baby names for 2013 - so far:

Why do names become popular? No-one really knows although with William being the most popular baby name in NSW for the past five years, there’s little doubt that its because of Prince William.

But while William has maintained its popularity, the most popular girls’ name has changed from year-to-year. Last year’s favourite, Ruby, has gone to number 10 with Charlotte shooting to top position. Coming second for each of the almost 100,000 boys and girls born in NSW so far in 2013 are the ‘twin’ names of Oliver and Olivia.

Other Australian states are not yet available, but NSW is in contrast to the most popular baby names sourced from 500,000 new parents in the US. That list is topped by Jackson and Sophia.

It’s the first year for Jackson and fourth consecutive year for Sophia. Second on the list are Aiden and Emma. William is ranked 20th in the US, while Charlotte is ranked 16th. 

The two lists share four boys names and seven girls names in common. Neither of NSW's most popular names appear in the US top 10 list.

“It’s not easy to say for certain why a name becomes popular,” says the Registrar of Births, Deaths and Marriages in NSW, Greg Curry.

“Names do come and go over the decades.”

He said names become popular for a number of reasons.

“The name may come from a ‘top 10’ list, a baby website, a family name, a popular celebrity or TV character, sportsman or world figure.”

Mr Curry says the main thing is for parents to be considerate when choosing a name for their baby.

“Their name is with them for life.”

Parents in Australia are required to register their child within 60 days of birth. Registration is free and is fundamental to establishing their legal identity for their entire life.

Top 10 lists for 2013 so far