According to the USCCB "Natural Family Planning (NFP) is the general title for the scientific, natural and moral methods of family planning that can help married couples either achieve or postpone pregnancies."...
"...Since the methods of NFP respect the love-giving (unitive) and life-giving (procreative) nature of the conjugal act, they support God's design for married love!"

These videos shared by the Archdiocese of Baltimore highlight why Natural Family Planning.