United Kingdom, June 23 -- Eric Christian Olsen and Sarah Wright Olsen have become parents for the fourth time.

The NCIS: Los Angeles star and his 41-year-old wife welcomed daughter Ocean Rain, a sister for Wyatt, 11, Esme, eight, and four-year-old Winter, into the world on 17 June following an "incredibly complex" labour.

The couple wrote in a joint Instagram post: "She's here!! Ocean Rain Olsen. Born 6/17 12:37am - 11 pounds 4 ounces.

"Grateful beyond words for our amazing team that helped us get her here safely during an incredibly complex birth. Cannot wait to share all the details of this day."

The post featured a series of posts of the couple in the hospital and posing proudly with their new baby.

The couple - who married in 20...