As the Zika virus bears down on the United States, federal health officials are divided over a politically and ethically charged question: Should they advise American women to delay pregnancy in areas where the virus is circulating?

Some infectious disease experts are arguing that avoiding conception is the only sure way to prevent the births of deformed babies, according to outside researchers who serve on various advisory panels.

Women’s health specialists, on the other hand, counter that the government should not tell women what to do with their bodies. Indeed, federal health officials have never advised all the women in a region of the country to stop having children. Moreover, they say, most babies conceived during Zika epidemics in Latin America have been born healthy.

Several federal experts central to the discussion declined to be interviewed for this article. Dr. Thomas R. Frieden, director of the Centers for Disease Control and Prevention, described the internal debate as “a very long conversation.”

For now, “we do not have a recommendation to not become pregnant,” Frieden said at a “Zika summit” held recently at the CDC’s headquarters in Atlanta. “We do recommend access to contraception.”

On Wednesday, the agency confirmed what many experts already believed: that the mosquito-borne virus, which is usually mild in adults, can cause severe brain damage in infants.

In view of the gathering evidence, health officials in some countries struck by Zika epidemics, including El Salvador and Colombia, have urged women to avoid pregnancy.

Dr. Marcos Espinal, who directs the Zika response of the Pan American Health Organization, an arm of the World Health Organization, said in an interview that he thought advising women to avoid conception during an epidemic’s relatively brief peak months, as Colombia did, “is sound advice.”

Yet the WHO does not follow that policy. Dr. Bruce Aylward, the agency’s head of emergency response, called avoiding pregnancy “a complicated decision that is different for each individual woman.”

Currently, the question affects Americans only in Puerto Rico, the U.S. Virgin Islands and American Samoa, where the Zika virus is circulating locally. But if the virus spreads as expected this summer, women in Hawaii and many Gulf Coast states may also be faced with tough choices.

Despite the CDC’s stance, Puerto Rico’s health secretary, Dr. Ana Rius, has been advising women to avoid pregnancy, although she has done so in public interviews, not in a large health campaign. Women on the island may be following her advice, she said; preliminary figures indicate that there are 8 percent fewer pregnancies than there were at this time last year.

For women living on those islands, the disease agency’s current guidelines do not advocate delaying pregnancy, instead calling the timing of conception a “deeply personal and very complex decision” and suggesting that women consult their doctors for “pregnancy planning.”

But tourists visiting the islands receive specific advice to avoid pregnancy for eight weeks after a visit, and for six months if male partners have had symptoms of Zika infection.

One expert familiar with the debate, Michael T. Osterholm, director of the University of Minnesota’s Center for Infectious Disease Research and Policy, described it as “two groups describing an elephant, one looking at the head and the other at the tail.”

Dr. William Schaffner, chairman of department of preventive medicine at Vanderbilt University Medical School, who also described the outlines of the split, said that withholding conception advice might leave couples adrift.

“They have to think it through by themselves,” he said. “They may hear it from their doctors or mothers or friends at the beauty parlor, but not from the CDC.”

Advocates of delaying pregnancy give several reasons.

First, they do not believe that even the most aggressive mosquito-control efforts can protect pregnant women 24 hours a day for nine months.

No country yet has stopped dengue or chikungunya, which, like Zika, are spread by the Aedes aegypti mosquito, and the disease agency itself has warned that reductions of 80 to 90 percent in those mosquito populations sometimes does not reduce disease transmission.

Second, no vaccine is expected to be ready for at least two years.

Third, evidence is mounting that Zika outbreaks are intense but brief. In French Polynesia in 2013, the virus infected 66 percent of the population within seven months and then disappeared.

Because women who recover from Zika appear to be permanently immune, experts argue that delaying conception spares them the risk of having a child with severe birth defects, along with the agonizing worry — and lets them conceive safely a year later.

“It’s a no-brainer,” said Dr. Peter J. Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine. “They should say, ‘Don’t get pregnant — watch TV for six months and you won’t have a badly hurt baby.’”

In framing the language of the guidelines, Frieden said he was “guided by the perspective” of Dr. Denise J. Jamieson, a medical officer in the CDC’s division of reproductive health.

In an interview, Jamieson described birth defects as a rare complication of Zika infection. Even during an epidemic, she said, “most women will have healthy babies.”

Further, Jamieson said, delays “would also prevent wanted pregnancies,” especially in older women struggling with fertility, for example.

Advice from government doctors on such personal decisions, she added, “is not likely to be effective.”

Asked what advice she would have given during the last American rubella epidemic — which killed or severely handicapped an estimated 20,000 babies — she answered: “I would have said, ‘This is an extraordinarily risky time to get pregnant.’”

But she does not endorse giving the same advice this time, she said, because rubella was unavoidable in those prevaccine days, whereas now, “highly motivated women can take measures to avoid mosquito bites.”

Local health officials have offered a variety of perspectives.

In the U.S. Virgin Islands, Michelle S. Davis, the territory’s new health secretary, said she had not advocated pregnancy delay, although individual doctors may be doing so.

The story has played out differently in Puerto Rico, where the CDC has said there could be thousands of pregnant women infected by late summer.

Rius, the health secretary, suggested in several public interviews that women delay conception until more is known about the virus. She also instructed public clinics to distribute condoms.

She was accused of alarmism, and the island’s Roman Catholic archbishop criticized her condom plan.

But in an interview at the Atlanta summit meeting, she said that a new pregnancy surveillance network created by the disease agency for the epidemic suggested that women there may be heeding her advice. Births are expected to number 28,000 this year, below last year’s total of 30,323.

Prominent gynecologists in Puerto Rico also are advising patients to avoid pregnancy.

Dr. Jose Alvarez Romagosa, a fertility specialist at the Auxilio Mutuo Hospital in San Juan and star of a popular TV show, “Latin Doctors,” said he had dissuaded three patients from conceiving in a single day.

Dr. Manuel Navas, a fertility specialist and medical director of HIMA-San Pablo Hospital in Fajardo, a town where some of the island’s earliest Zika infections were detected, said he, too, was discouraging most patients from conceiving unless they were desperate for a child and he was sure they understood the risks.

That was the advice he would give his daughter, he added.

Asked how his patients reacted, he said, “They appreciate it.”

© 2016 The New York Times Company