"the foremost cause" is a correct and usable phrase in written English. You can use it when you want to describe something as the most significant or important cause of a certain effect. For example, "The foremost cause of the catastrophe was the failure of the dam's safety system.".
"Life is the foremost cause in how I vote.
To demand a ban on lead ammunition (lead poisoning is the foremost cause of California condor deaths) would alienate hunters.
"Boldness of enterprise is the foremost cause of [America's] rapid progress, its strength and its greatness," Alexis de Tocqueville wrote nearly a couple of centuries ago.
Trauma is the foremost cause of death in young patients.
Pneumonia is among the foremost causes of hospitalization and mortality in patients residing in extended care facilities [1 8].
Pneumonia is among the foremost causes of hospitalization and mortality in patients residing in extended care facilities.
Tubercular infection constitutes one of the foremost causes of death and morbidity across the world, more so in the tropical region.
When I feel like I can't trust my brain 100%, Ludwig really comes in handy. It makes me translate and proofread faster and my output more reliable.
Claudia Letizia
Head Translator and Proofreader @ organictranslations.eu