But he went a step further and strongly criticized those couples who choose not to have children, saying they had been influenced by a culture of "well-being" that says life is better without kids.
"You can go explore the world, go on holiday, you can have a villa in the countryside, you can be carefree," the pope said. "It might be better more comfortable to have a dog, two cats, and the love goes to the two cats and the dog. Is this true or not? Have you seen it?
"Then, in the end this marriage comes to old age in solitude, with the bitterness of loneliness."
The 77-year-old pontiff made his comments after recent figures confirmed a drop in birthrates in the U.S., Italy and elsewhere.
Figures released by Italy's official statistics agency Istat last week showed the country's birthrate hit a record low in 2013, with the birth of 515,000 babies a drop of 64,000 during the past five years and a worrying trend as the population ages.
Last year, Time magazine provoked a national debate with a controversial issuetitled "The Childfree Life," which also showed a dramatic fall in the U.S. birthrate and the role of personal choice.
"Married life must be persevering, because otherwise love cannot go forward," the pope said. "Perseverance in love, in good times and in difficult times, when there are problems: problems with the children, economic problems."