A spokeswoman for Middleton and her husband James Matthews said Tuesday that their first baby had been born the day before.
Kensington Palace says that Prince William and Kate are “thrilled for Pippa and James.”
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Middleton, 35, first came to public attention when she acted as maid of honour at the 2011 wedding of her sister Kate to Prince William, who is second in line to the British throne.
Middleton married financier Matthews last year.
The new baby will be a cousin to William and Kate’s three children — George, 5, Charlotte, 3, and 5-month-old Louis.
— With files from Reuters
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