The Dane has been sidelined since May after suffering a fractured neck vertebra – the second time he had fractured the same vertebra in eight months.
Despite a scan on Monday showing some progress, Pedersen did not receive the all-clear from doctors to resume racing and will undergo further scans in November, with a view to returning to action in 2018.
His place in Stockholm, Torun and Melbourne will be taken by SGP second reserve Martin Smolinski of Germany, with first stand-in Peter Kildemand already replacing injured world champion Greg Hancock for the rest of 2017.
Third reserve Max Fricke steps in for Niels-Kristian Iversen in Stockholm on Saturday. The Dane is recovering from a broken shoulder, but hopes to return in either Torun or Melbourne in October.
We wish Greg, Nicki and Niels a speedy recovery.