Life & Style has exclusively learned that Kate Middleton's pregnant with her third child — and there's at least one person who isn't happy about it!

The Duchess' sister, Pippa Middleton, recently got engaged to hedge fund manager James Matthews, and doesn't want news of another royal baby to steal her spotlight.

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"Pippa is worried that Kate's pregnancy will overshadow the nuptials," a source says. "Pippa desperately wants the focus to be on her rather than her sister's baby bump."

kate middleton pippa middleton getty images

Pippa and Kate in 2012.

The 33-year-old has even considered rescheduling her big day. "She may put off the wedding until Kate has had her baby," a friend reveals. "Pippa is planning things around Kate."

For more pregnancy news, pick up the latest issue of Life & Style, on newsstands now! And take a look back at Kate’s maternity style in the gallery below.