In an address to an international society for the promotion of natural family planning, the Holy Father commended the group for its research on human fertility, and stressed that "responsible parenthood" might compel some married couples to use the natural periods of a woman's fertility as a means of regulating births. However, he cautioned that couples should use this method, too, in a way that is "truthful to their love." The use of natural family planning can also be subject to abuse, he said, if couples avoid having children simply in order to make their own lives easier or more affluent.
The Holy Father recommended that pastors should show "understanding" toward the many couples who have difficulty fulfilling the natural plan of marriage. But he emphasized that such "understanding" should not mean ignoring the laws of nature and the teachings of the Church.