Actor Robert De Niro and his wife Grace Hightower have welcomed their second child together.

The couple's daughter Helen Grace was born via a surrogate mother.

According to a statement issued to People magazine from the New Year's Eve actor's representatives, baby Helen weighed in at 3.18 kg.

De Niro and his 56-year-old wife Grace first met in 1987 in London and were married in 1997. They have 13-year-old son Elliott together.

Robert and Grace temporarily split in 1999, but they renewed their vows in 2004.

Grace is Robert's second wife.

The 68-year-old Academy Award-winning actor has six children in total.

His 16-year-old twin sons with ex-girlfriend model Toukie Smith, Julian Henry and Aaron Kendrick, were conceived through in vitro fertilisation. The boys were also delivered via a surrogate mother.

Robert has a son named Raphael with his first wife Diahnne Abbott, whom he divorced in 1988. The actor also adopted Diahnne's daughter from a previous relationship, Drena.