Sentence:  In 1920 , the Lambeth Conference repeated its 1908 condemnation of contraception and issued `` an emphatic warning against the use of unnatural means for the avoidance of conception , together with the grave dangers - physical , moral , and religious - thereby incurred , and against the evils which the <WSD>extension</WSD> of such use threaten the race '' . 
Meaning of the word marked with <WSD> tags:  the spreading of something (a belief or practice) into new regions