In fact, to some North American liberals, anti-surrogacy stances seem at odds with the values of gender equality and gay rights. After all, if women are allowed to purchase sperm for insemination, why shouldn’t men be allowed to pay for eggs and surrogacy services? Surrogacy also enables gay couples to have biological children, a prerogative that would otherwise be limited to heterosexual couples.

Yet in Europe, it is not uncommon to see opposition from the left. In France, for instance, the country’s largest lesbian association, the Coordination Lesbienne, has opposed surrogacy since 2011, and progressive feminists like the philosopher Sylviane Agacinski have joined the cause. In Sweden, it was a social democratic government—one that prided itself on being “the first feminist government in the world”—that banned surrogacy in 2016. Spain’s Feminist Party has also objected to it.

Not all European feminists reject this practice: In Italy, for instance, Se Non Ora Quando—Factory, a group that split from Se Non Ora Quando over this issue, supports surrogacy, arguing that “the desire of becoming a mother and a father has acquired new meanings.” Still, anti-surrogacy stances are quite mainstream in European feminism.

“To me, fighting surrogacy, it’s part of fighting the patriarchy,” Terragni said. “For thousands of years the patriarchy has tried to reduce women to livestock for reproduction, and this is a newer, more extreme form of it.”

Terragni explained that as a feminist activist she supports “the affirmation of feminine difference,” or the idea that women have a more central role in reproduction than men and that this primacy needs to be cherished and protected. “It’s something that the patriarchy has tried to take away from women, from the days of Aristotle, who described women’s wombs just as containers for semen.”

It’s because of this “affirmation of feminine difference” that she supports sperm donation for single women and lesbian couples, but opposes surrogacy.

This focus on “feminine difference,” a concept widespread among European feminists and popularized by the French anthropologist Françoise Héritier and by the Belgian philosopher Luce Irigaray, may help explain why continental brands of feminism have been keen to oppose surrogacy, while the practice seems almost a non-issue in America’s mainstream feminism.

“Traditionally, Anglo-Saxon feminism has been mostly about emancipation—its goal is to make women equal to men,” Terragni said. “In Europe, ‘difference feminism’ is more common.” The result is a “strategic alliance” between conservative Catholics and left-wing feminists, she said.

However, Tamaro, the bestselling novelist who addressed the conference in Rome, emphasized that it would be wrong to portray the anti-surrogacy argument as solely Catholic or feminist. “I was never a feminist and Catholicism isn’t part of my background, as I was brought up in an atheist family with Jewish roots,” she told me in an email. “It’s a much wider and more complex issue, in which the very idea of humanity is at stake.”