Davis passed away last May (11), a day after undergoing an operation on her knee to fix an old sports injury.
Los Angeles coroners ruled her official cause of death was a "pulmonary thrombo-embolism" - a blood clot in the lungs - although they listed the surgery as a "significant condition contributing to death".
Her grieving widower Mike Yard, who wed the plus-sized actress in 2008, is now convinced the type of contraception she was on, Balziva and Zenchent, "greatly increased her risk for a pulmonary embolism and ultimately caused her death".
He claims her obstetrician should have known better than to prescribe the overweight Davis with the drugs. Yard is adamant his wife should have been offered an alternative type of birth control, because "obesity" is a well-known risk factor with those pills.
Yard also alleges the doctor who cleared Davis for treatment on her knee was wrong to do so because she was obese, adding he "should have advised (Davis) to eliminate some of her other risk factors prior to clearing her for the surgery".
He is seeking unspecified damages from both the obstetrician and the surgeon for the loss of love, companionship and moral support, reports TMZ.com.