In her fifth month of pregnancy, Dana Edell learned that she was carrying a boy. Her parents, who are Conservative Jews, asked about the ritual circumcision.

“Well, what if I’m considering not circumcising?” Ms. Edell recalled saying. “My parents looked at me like I had just said, ‘Well, what if I’m considering sacrificing him to Satan?’”

For thousands of years, Jewish families have marked the beginning of a boy’s life with a bris ceremony on the eighth day after birth. A bris includes a circumcision performed by a mohel, or a ritual circumciser, and a baby naming. The practice is rooted in Genesis, when God instructs Abraham to circumcise himself and all of his descendants as a sign of their contract with God.

But some Jewish parents, aghast at what they see as unnecessary infliction of pain or even mutilation, are retreating from the ancient ritual. Some are choosing to forgo the bris in favor of a medical circumcision. Others are opting out of circumcision altogether.