Katy Perry's boyfriend Diplo is having a baby with his ex-girlfriend.

The DJ and music producer and his former flame Kathryn Lockhart are having a second child together, a sibling for their four-year-old son, Lockett.

It is thought Kathryn was ''newly pregnant'' when Diplo - real name is Wesley Pentz - began dating Katy in April this year.

A source told the New York Daily News newspaper's Confidenti@l column: ''She's due in the next couple of weeks. Her friends recently had a baby shower for her. She and Wes aren't together, but he's actively involved in (Lockett's) life.''

The news comes just weeks after Katy - who was married to comic Russell Brand for 14 months until December 2011 and has dated lothario John Mayer in the past - was said to be feeling ''in control'' of the relationship and keen to keep their blossoming romance ''undercover''.

A source said: ''She's keeping this one undercover because she's learned her lesson. She's in control, but he likes that.

''He knows she's in charge and respects her. She keeps tabs on him ... but she trusts him and that's the most important thing to her.''

Katy, 29, has already introduced Diplo, 35, to her family as their relationship gets more serious.

The source said: ''Her family likes him a lot. You can see how comfortable she feels with him already because the whole crew hangs with him already and they approve. It's important that everyone gets along with him because makes her crazy life easier.''