Sentence:  In 1930 , the Lambeth Conference again affirmed the primary purpose of marriage to be the procreation of children , but conceded that , in certain limited circumstances , <WSD>contraception</WSD> might be morally legitimate . 
Meaning of the word marked with <WSD> tags:  birth control by the use of devices (diaphragm or intrauterine device or condom) or drugs or surgery