Circumcision has been shown reduce the risk of some sexually transmitted infections, including herpes, syphilis and H.I.V. However, the H.I.V. studies were done in Africa, where overall H.I.V. rates are much higher, and where, unlike in the United States, heterosexual sex is the main mode of transmission. (Studies investigating whether circumcision helps protect against H.I.V. in men who have sex with men have been inconclusive.) Researchers don’t yet fully understand the mechanism by which circumcision reduces H.I.V. transmission; some have suggested that tiny abrasions in the delicate foreskin, combined with a warm, moist environment, may leave uncircumcised men more vulnerable to infection. Circumcising to prevent H.I.V. in the United States doesn’t make sense from a cost and risk standpoint, said Dr. Timothy Johnson, M.D., a professor of obstetrics and gynecology at the University of Michigan Von Voigtlander Women’s Hospital. Dr. Laurie Schulwolf, M.D., a pediatrician at Tribeca Pediatrics in New York City, put it even more bluntly. “For H.I.V. and S.T.D.s,” Dr. Schulwolf said, “a condom goes so much further than a circumcision.”

Understand that the risks of circumcision are low.

Only about 1.5 percent of circumcised infants experience complications during the five years after the surgery. Bleeding and infection are the most common complications, and must be addressed by a doctor right away, Dr. Freedman said. Adhesions, which occur when skin from the shaft of the penis sticks to the tip, are also common; these often resolve on their own, but may require treatment with a steroid cream, such as betamethasone, Dr. Shapiro said. An untreated adhesion can go on to form a thickened band of skin called a skin bridge, which may need to be surgically removed. Another less common complication of circumcision, meatal stenosis, occurs when inflammation and scarring compress the urethra, making urination difficult.

Overall, circumcision is a safe, low-risk procedure for newborns, said Dr. George Mussalli, M.D., an obstetrician at Village Obstetrics in Manhattan and an associate professor of clinical obstetrics and gynecology and women’s health at Albert Einstein College of Medicine.

Consider the non-medical aspects of circumcision.

Globally, circumcision rates vary widely. Since both Jewish and Islamic religious traditions promote the procedure, circumcision rates are over 95 percent in parts of the Middle East. In Western Europe, where non-medical infant circumcision has become increasingly controversial, and children’s rights groups have proposed banning the circumcision of minors, rates are under 20 percent. “In much of the world, newborn circumcision is not primarily a medical decision,” wrote Dr. Freedman, in a 2016 paper on the circumcision debate. Even in the United States, he noted, where “parents may use the conflicting medical literature to buttress their own beliefs and desires,” most parents ultimately decide whether or not to circumcise for non-medical reasons. “There can be no doubt that religion, culture, aesthetic preference, familial identity and personal experience all factor into their decision,” Dr. Freedman wrote.

It may be helpful for parents to consider their cultural context, said Dr. Allan Jacobs, M.D., director of gynecological oncology at Coney Island Hospital and a professor of obstetrics, gynecology and reproductive medicine at Stony Brook University School of Medicine. “Someone might think, ‘If I’m living in Sweden, maybe I won’t circumcise, but if I’m living in Israel, I will.’”

“I try to get parents to say why they are doing it,” said Dr. Freedman, who advises parents to weigh the cultural, medical and other aspects of the decision and then to do what they believe is in the best interests of their child. “If it is important for you to do it for non-medical reasons, you should be allowed to do it,” Dr. Freedman continued. “You shouldn’t feel pressured either way.”

If you decide to circumcise, take steps to minimize complications.

Before being circumcised, an infant must be cleared by a doctor; he should not be underweight, and should not have a bleeding disorder or other serious medical issues. To reduce complications, the circumcision should be done by a trained practitioner — typically an obstetrician, sometimes a pediatrician — who uses sterile techniques. The procedure is quick, lasting only 10 to 15 minutes, and parents may be present if they wish. In the past, babies were often circumcised without anesthesia, but most providers now use some form of pain relief. Your doctor may apply a topical anesthetic cream, or inject a local anesthetic, to numb the penis before the procedure. If you plan to circumcise your son, it is best to do it before 6 weeks of age; afterward, circumcision must be done with general anesthesia in an operating room. In addition, the risk of complications increases with the age of the baby.