A set of twins born 15 minutes apart in California have very different birthdays -- one in 2021 and the other in 2022.

Alfredo Antonio Trujillo came into the world at 11:45 pm on New Year's Eve in the city of Salinas.

A quarter of an hour later, on New Year's Day, his sister Aylin Yolanda Trujillo was born.

The Natividad Medical Center, where the babies were delivered, said in a statement last week that some estimates suggest there is a one-in-two-million chance of twins being born in different years.

"It's crazy to me that they are twins and have different birthdays," the babies' mother, Fatima Madrigal, was quoted as saying in the statement.

Dr. Ana Abril Arias described the births as "one of the most memorable deliveries of my career."

"It was an absolute pleasure to help these little ones arrive here safely in 2021 and 2022."

Big brother Alfredo tipped the scales at six pounds and one ounce (2.75 kilograms) while the baby of the family, Aylin, was a healthy five pounds and 14 ounces.

The Centers for Disease Control and Prevention says around 120,000 twins are born every year in the United States, representing roughly three percent of births.