London, Aug 21 : Britney Spears' younger sister, Jamie, who recently gave birth to a baby girl, seems to be shaken by fiance Casey Aldridge's infidelity rumours.

Jamie looked a bit reticent as she cradled her two-month-old tot during their shopping trip.

Casey's ex-girlfriend Kelli Dawson recently rocked the Spears family when she revealed to an American tabloid that she enjoyed an affair with Aldridge while Jamie was six months pregnant, reports The Sun.

Britney's first husband had confirmed Dawson's claim by stating that the fling was of common knowledge in their hometown.

However Casey, who is to wed girlfriend Lynn later this year, has denied any such allegations.

ANI