Although the construction appears to be more common in magazine and newspaper writing than in formal prose, beginning a sentence with because is both acceptable and widespread.

Because is more common than as and since, both in writing and speaking. When we use because, we are focusing on the reason: …

BECAUSE definition: for the reason that; due to the fact that. See examples of because used in a sentence.

Definition of because conjunction in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

Usage: The phrase on account of can provide a useful alternative to because of in writing. It occurs relatively infrequently in spoken language, where it is sometimes followed by a clause, as in on …

You use because when stating the reason for something. He is called Mitch, because his name is Mitchell. Because it is an area of outstanding natural beauty, you can't build on it. Temple could …

Use because before the reason or cause for something when there are two clauses you are joining; use because of when a noun phrase, not a clause, describes the reason for something.

"Because" is a conjunction used to show cause or reason. It introduces a clause that explains why something happened or why someone holds a certain opinion or belief.

Sometimes, however, because is perfectly appropriate as the opening word of a sentence. In fact, sentences beginning with because are quite common in written English, as in this example from …

Don't get nervous just because the teacher might ask you a question. We can't assume it will rain today just because it rained yesterday. Just because your friends do it, that doesn't mean that you should …