Lovin tweeted on 10 February "Our little love has finally arrived. Mark @phlipapparel & I are full of excitement and joy:)".
Lovin, a Romanian-Australian who describes herself as a model/actor/artist, was very open during her pregnancy, regularly posting updates and photos on social media.
Her approach to motherhood looks like it will be similar, tweeting a few hours later "Love being a mum! It's the best feeling in the world:)".
Lovin posted this image on Instagram.
She later tweeted a picture of her apparently singing a lullaby to the baby. "Rock-a-Bye-Baby...#sleepytime#singinglullabysongs."
Philippoussis and Lovin were married in a private ceremony at the end of 2013 and live in California where Philippoussis runs a tennis academy.
In 2012 he launched his own fashion label called Phlip Apparel, specialising in t-shirts and adopting the alluring motto "same shirt, all occasions".
Mark Philippoussis was a top 10 tennis player and famous for his strong serve which earned him the nickname 'the Scud' (after the Scud missile) and the Australian tennis record for most aces served in a match.