This is an autobiographical novel that Koichi wrote about his own forbidden love.
The doctor forbade the pregnant woman from alcohol and cigarettes.
In this room, whispering is prohibited.
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means prohibition so the verb version means to prohibit.
This has the same reading as the kanji you learned, meaning you know the reading!