New mum Serena Williams has revealed details of the complications surrounding the birth of her baby girl who was born on September 1. The tennis superstar and her boyfriend Alexis Ohanian have now debuted their offspring on Instagram - and the little one has been named after her daddy.

Serena WilliamsSerena Williams has given birth to a baby girl

In the introductory picture, Serena - who was pregnant with the tot when she won her 23rd Grand Slam at the Australian Open in January this year - is holding her six day old with the caption: "Meet Alexis Olympia Ohanian Jr. You have to check out link in bio for her amazing journey. Also check out my IG stories."

The American went into further detail about her birth and revealed they had spent six days in hospital.

MORE: Serena Williams Welcomes A Baby Girl

Serena’s Instagram story, plus a video shared to Serena’s official website, showed Alexis’s journey into the world.

Beginning at Serena’s baby scan, we saw selfies of the athlete with a growing bump, behind the scenes Snapchats of her tummy moving, all culminating in the baby’s birth.

Serena hinted at a difficult birth, saying: "We had a lot of complications, but look who we got!"

The end of the video announced that the baby was called Alexis Olympia Ohanian Jr, and that she weighed 6lbs 14oz.

And, amazingly, she’s listed as having won one Grand Slam title, seeing Serena was pregnant during the Australian Open.

MORE: Serena Williams Asks Reddit For Pregnancy Advice

The star accidentally revealed she was pregnant at 20 weeks when she made a Snapchat of her bulging bump public.

Fortunately for all involved, there were no issues that would mean she had been too quick to reveal her pregnancy.

The star became engaged to Reddit co-founder Ohanian last December.