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 <WSD>conception</WSD> , together with the grave dangers - physical , moral , and religious - thereby incurred , and against the evils which the extension of such use threaten the race '' . 
Meaning of the word marked with <WSD> tags:  the act of becoming pregnant; fertilization of an ovum by a spermatozoon