No.9-ranked Kvitova won her 31st WTA singles title on Sunday in Berlin.
The two-time Wimbledon champion was due to start her defence on Tuesday against Jelena Ostapenko, whom she beat in last year's final. Latvia's Ostapenko won the 2021 title and the Birmingham trophy on Sunday.
Ostapenko beat Kvitova's replacement, Barbora Strycova, 6-4 6-3 in the first round to set up a last-16 clash with Britain's Harriet Dart.
Czech Kvitova followed the exit of Wimbledon titleholder Elena Rybakina on Monday. Kazakhstan's Rybakina was the top seed but withdrew because of a viral illness, tournament organisers said.
The field was newly led by No.5-ranked Caroline Garcia and included four others in the top 10 this week: Jessica Pegula, Ons Jabeur, Coco Gauff and Barbora Krejcikova.
Second-seeded Garcia of France advanced to the last 16 to face Romanian Ana Bogdan with a 6-1 7-5 win over American Madison Brengle.
Fifth-seeded Gauff beat Bernarda Pera 6-3 6-2 with the all-US clash lasting 61 minutes.
"Bernarda is not an easy player, especially a lefty on grass," Grauff said.
"It was really windy today so I think we were just trying to make one more ball in the court."
Gauff next faces British player Jodie Burrage.
Pegula also advanced in straight sets by beating Zheng Qinwen of China 6-3 6-4 in the first meeting between the two players. The third seed plays Colombian qualifier Camila Osorio next.
Tunisian Jabeur, the former Wimbledon and US Open finalist, beat Jasmine Paolini of Italy 6-3 6-2 to set up a match with Italian Camila Giorgi, while Brazil's Beatriz Haddad Maia battled back to triumph 3-6 6-3 7-6 (7-3) against Czech Marie Bouzkova.
With AP.
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