Francis said Catholics don't have to "be like rabbits" and have more children than is safe or responsible. He said there are plenty of church-approved ways to regulate births. But he said most importantly, no outside institution should impose its views on families.
Speaking to reporters en route home from the Philippines, he said: "Every people deserves to conserve its identity without being ideologically colonised."
On the trip, he gave his strongest defence yet of the 1968 encyclical Humanae Vitae, which enshrined the church's opposition to artificial birth control.
He warned against "insidious attacks" against the family, a reference to gay marriage proposals, echoing language often used by overwhelmingly conservative US bishops. And he insisted that "openness to life is a condition of the sacrament of matrimony."
He cited the case of a woman he met who was pregnant with her eighth child after seven Cesarean sections.
"That is an irresponsibility!" he said. The woman might argue that she should trust in God. "But God gives you methods to be responsible," he said.