Vidya Balan reportedly went unnoticed when director Sujoy Ghosh made the actress walk on the streets of Kolkata in a pregnant get-up before beginning the shoot for his upcoming film 'Kahaani'.

According to the grapevine, the 34-year-old actress mingled with the crowd so much that a co-passenger even got up to offer his seat to her in a tram.

In the movie, Balan plays a pregnant woman in search of her husband and the father of the child.

It is scheduled to release on March 9.