Pope Francis called on Monday for a global ban on surrogacy, saying the practice of a woman carrying another person's child was "deplorable".
In his New Year's address to diplomats at the Vatican, the 87-year-old pontiff said it was a "grave violation of the dignity of the woman and the child".
In a speech dominated by calls for an end to conflicts around the world, the head of the worldwide Catholic Church said: "The path to peace calls for respect for life."
This began "with the life of the unborn child in the mother's womb, which cannot be suppressed or turned into an object of trafficking", he said.
"In this regard, I deem deplorable the practice of so-called surrogate motherhood, which represents a grave violation of the dignity of the woman and the child, based on the exploitation of situations of the mother's material needs.
"A child is always a gift and never the basis of a commercial contract. Consequently, I express my hope for an effort by the international community to prohibit this practice universally."
In June 2022, the pope condemned surrogacy as an "inhuman" practice.
"Altruistic" surrogacy, whereby a woman gives birth to a baby on behalf of another woman or couple but no money changes hands, excluding for expenses, is legal in countries including Belgium, the Netherlands, the UK, Canada, Brazil and Colombia.
Commercial surrogacy is permitted in some US states.