When Kevin Gruenberg’s wife was pregnant, he was anxious, irritable, and preoccupied with the thought that his stomach was growing. He kept thinking of a family story, from when his mother was pregnant with him, and his father gained weight in parallel. In 2014, three decades later, Gruenberg was having a similar experience, though it went beyond overeating. And although he is a psychologist in Los Angeles, he didn’t know where to turn for help.

Gruenberg, who today leads an organization that runs support programs for fathers called Love, Dad, felt brushed off by his friends. Discouraged and alone, he began to research couvade syndrome, in which men experience pregnancy symptoms. It was, he said, something that he “definitely felt psychologically and physiologically.”

The term couvade first appeared in a book by a British anthropologist, Edward Burnett Tylor, in 1865. It comes from the French word couver, to brood or hatch. In its earliest documentation in the scientific literature, male pregnancy symptoms were seen as purely psychosomatic. Today, the syndrome’s loose definition means its prevalence is hard to track. But couvade, as it is commonly referred to, has appeared in the United States, China, Thailand, and other countries, according to Arthur Brennan, a British labor-and-delivery nurse turned lecturer at Kingston University, in the United Kingdom.

Some researchers are now hypothesizing that the more involved in child-rearing a father is, the more his mind and body might change. Lee Gettler, an anthropologist at the University of Notre Dame, has studied fathers across the world. He told me he suspects that changes in men’s testosterone levels as they become dads depends in part on cultural norms of fatherhood. Robin Edelstein, a psychologist at the University of Michigan who has studied hormones and fatherhood, has also wondered whether these hormonal changes occur on a feedback loop. In her research, the fathers who were most involved with child care had the lowest testosterone levels, and she theorized to me that the more time dads participate in child care, the lower their testosterone levels might go.

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