LOS ANGELES (AFP) - Cleveland Cavaliers guard J.R. Smith's wife has given birth to the family's third daughter, Dakota, five months before she was due, the couple revealed on Saturday.

Dakota Smith is five days old and weighs just 450 grams, Smith and Jewel Harris said on Uninterrupted - the online video platform for athletes that was created Smith's team-mate LeBron James.

The average birth weight of a baby is about 3.4kg.

The Smiths announced on Uninterrupted in October that they were expecting.

"We know we're not the only family going through this, who has been through this or who will ever go through it," an emotional Harris said. "That's why we decided to share what we've been going through with you guys. Please keep us in your prayers and we'll do the same for everybody else."

The couple did not share any other information.

Smith recently had thumb surgery and is not expected to play for the defending National Basketball Association champion Cavaliers until March at the earliest.