Opting not to have children is "a selfish choice," Pope Francis warned at the Vatican on Thursday.

The leader of the world's more than 1.2 billion Catholics noted "life rejuvenates and acquires energy when it multiplies," according to the Religion News Service.

"It is enriched, not impoverished!" the pontiff insisted.

A society that "views children above all as a worry, a burden, a risk is a depressed society," Pope Francis said. The pope referred specifically to European nations, where the fertility rate is particularly low.

"They are depressed societies because they don't want children," he summarized. "They don't have children. The birth rate doesn't even reach 1 percent!"

Francis reiterated his support for "Humanae Vitae," the 1968 encyclical, or papal message, in which Paul VI solidified the Catholic Church's ban on artificial contraception.

With his remarks at Thursday's gathering in St. Peter's Square, Pope Francis seemed to relativize comments he made last month during an in-flight news conference on his return to Rome from the Philippines, according to the to the Religion News Service. Catholics should not be "irresponsible" by making children "in series," Pope Francis said.

"To be good Catholics, we (need not) be like rabbits," he said at the time.

The quote led to questions about whether Pope Francis was revising the Church's teaching on birth control, but the Vatican later made clear that that was not his intention. At a general audience two days after his return, the pontiff praised big families for "welcoming children as a true gift of God."

Observers have been startled by the pope's seemingly conflicting statements on a number of issues.

"Francis has flip-flopped in his opinions on (gay and lesbian) matters," The Independent reported.

Last year, the pontiff already warned against what he dubbed a "culture of wellbeing," the ability of childless couples to enjoy such luxuries as pricey vacations or a second home in the countryside, The Guardian noted.

Two years ago, Pope Francis spoke to a journalist about the LGBT community.

"If a person seeks God and has goodwill, then who am I to judge?" he said.

In November, however, Pope Francis took a tough stance on same-sex unions, insisting that marriage is an institution between one man and one woman.

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