Lance Armstrong has become a father for the fourth time after girlfriend Anna Hansen gave birth to a baby boy yesterday.

Lance announced the arrival of his new son via his Twitter page last night. He posted a message from the 7lb 5oz boy saying: “Wassup, world? My name is Max Armstrong and I just arrived. My Mommy is healthy and so am I!”

The seven-time Tour de France winner posted a picture of the newborn and a photo of the medical staff who helped deliver the boy, saying they “were amazing!!”

Lance has three older children - nine year old son Luke and 11 year old twins Isabelle & Grace - from his previous marriage to Kristin Richards. They were conceived using sperm frozen before Lance underwent chemotherapy for testicular cancer - but Max “was conceived naturally” according to a spokesperson for the cyclist.