Pope Francis has sent a message to a Natural Family Planning (NFP) conference in which he upheld the central teachings of Humanae Vitae, the papal encyclical of 1968 that prohibited married Catholics from using contraception.

The Pontiff stated that the unitive and procreative aspects of sexual intercourse were “inseparable” and he called for a counter-sexual revolution.

He warned Catholics that the widespread use of contraception had impoverished many societies and that some countries were now in danger of demographic collapse.