06/05/2009 AT 01:50 AM EDT
Time to get a child seat for that racing bike.
Lance Armstrong and girlfriend Anna Hansen welcomed a 7 lb., 5 oz, 20-inch-long baby boy named Max, the pro cyclist announced on his Twitter page Thursday night – or, rather, the little guy announced it himself.
"Wassup, world? My name is Max Armstrong and I just arrived. My Mommy is healthy and so am I!" says the post, which includes a photo
of the baby in a cap and sticking his tongue out.
In another post, Armstrong includes a photo of the nurse and doctor who helped deliver Max. "They were amazing!!" writes Armstrong.
The seven-time Tour de France winner and cancer survivor, who is making a comeback to pro cycling, announced
last December that he and Hansen were expecting their first child together.
He has three children with ex-wife Kristin. The children were conceived through in vitro fertilization with sperm frozen prior to Armstrong undergoing chemotherapy for testicular cancer.