January Jones shows baby off on set

January Jones took her newborn to work with her, so she could show him off to all of her Mad Men castmates.

The new mum was photographerd cradling little Xander on her second day back on set, where she introduced the child to co-stars, including John Slattery.

Jones gave birth to the baby boy on September 13. She still has yet to confirm the name of the father and accoriding to TMZ.com has even left his name off the birth certificate.

Even after only giving birth four weeks ago, the single mum looked very slim on set. It seems all of the yoga that she done whilst pregnant certainly paid off.