Sentence:  Pope Pius 12 , declared in 1951 that it is possible to be exempt from the normal obligation of parenthood for a long time and even for the whole duration of married life , if there are <WSD>serious</WSD> reasons , such as those often mentioned in the so-called medical , eugenic , economic and social `` indications '' . 
Meaning of the word marked with <WSD> tags:  concerned with work or important matters rather than play or trivialities