This month, the first group of babies in Puerto Rico known to have been exposed to the Zika virus in their first trimester are being born. Pediatricians do not know what to expect.

“This is not like any other outbreak or epidemic,” said Dr. Fernando Ysern, a pediatrician in Caguas, Puerto Rico, who is the president of the Puerto Rico chapter of the American Academy of Pediatrics.

In the pediatric field, Zika looms as a kind of developmental doomsday virus, attacking the vulnerability of early brain development, striking at the neurological basis of human potential. While Puerto Rico, a United States territory, will experience the first wave of children affected by Zika, the rest of the United States is bracing for the spread of the virus.

As of Sept. 23, the Puerto Rico Department of Health reported 22,358 cases of Zika exposure, including 1,871 pregnant women. The Centers for Disease Control and Prevention’s latest statistics, as of Sept. 15, list 1,348 pregnant women with “any laboratory evidence of possible Zika virus infection” in United States territories and 749 in the United States.

Exposure to Zika while pregnant does not mean a child definitely will be born with microcephaly, an unusually small brain and head, or have Zika-related health problems. But the risk is real, and pediatricians are trying to figure out how to follow these children, and how to take care of the ones who do have problems. While nobody knows the actual risk of Zika exposure to a fetus, studies have suggested that between 1 percent and 13 percent of pregnant women infected with Zika in the first trimester will have a child with microcephaly, but more could have children with more subtle developmental problems related to in utero exposure to the virus.

Earlier this month, the American Academy of Pediatrics announced a $350,000 grant from the Department of Health and Human Services to create a network of pediatricians prepared to deal with a generation of children with Zika-related health problems. When babies are born with damaged brains because of Zika they will need medical care and their families will need support.

But how do you prepare for a new and evolving and still poorly understood clinical challenge? Pediatric experts got together over the summer to talk about it. The meeting was convened by the Centers for Disease Control and Prevention in collaboration with the American Academy of Pediatrics, and it brought together a range of pediatric subspecialists, from neonatology and neurology, infectious diseases and developmental behavioral pediatrics, rehabilitation medicine, ophthalmology and orthopedics and more.

There’s so much we don’t know. Dr. Peter Jay Hotez, the dean for the National School of Tropical Medicine at Baylor College of Medicine in Houston, said several big questions need to be answered. How does the virus do its damage? What is the full spectrum of damage, from the clearly visible microcephaly to less visible neurological changes? And what happens to babies exposed to Zika after birth, when the brain is still developing?

The meeting yielded interim guidelines, published in the C.D.C. Morbidity and Mortality Weekly Report. “Initially at C.D.C., our biggest goal was to make sure pregnant women didn’t get Zika,” said Dr. Sonja Rasmussen, a pediatrician and clinical geneticist who is the director of the Division of Public Health Information Dissemination at the C.D.C. “This meeting was really trying to make sure those babies have the best chance to reach their fullest potential.”

For the children born with microcephaly, whose fetal brain growth has clearly been disrupted by the virus, the recommendations draw on the very recent and quickly evolving experience of doctors in Brazil. These babies are at risk for seizures, feeding problems, tightly contracted joints, thyroid problems, eye problems, and developmental delays. They need regular neurological examinations, hearing tests, vision tests, hormone tests and lots of medical backup.

“If you see a child who has such significant microcephaly, you know the issues,” said Dr. Fan Tait, a pediatric neurologist who is one of the associate directors at the A.A.P. and took part in the meeting.

To provide decent care for these children, to support their families, requires subspecialists, coordination, and a profound commitment to complex care. That kind of care is not always available, especially for children from less advantaged homes, and there’s a concern that Zika, like so many other diseases, may play out along the lines of privilege, with poor people more likely to be exposed, either because of less protected living situations or jobs that keep them outside.

“No one’s really sure of the magnitude of what we will be dealing with,” said Dr. Tait.

And what about the children with normal sized heads at birth, who are known to have been exposed to this virus, which targets the developing brain? Dr. Rasmussen asked, “Is the microcephaly just the tip of the iceberg or are those kids without microcephaly at birth going to be just fine?” What kind of monitoring is necessary when the babies look normal?

It’s a delicate balance, that watching and waiting, because you don’t want to label children, or create extra parental anxiety. But on the other hand, the less visible developmental problems are exactly where all our experience shows that early watchful diagnosis may make a difference.

“We do know that if children have hearing loss, vision problems, developmental delay, it’s best if it’s identified early,” Dr. Rasmussen said. The interim guidelines recommend “additional monitoring, until further information is available regarding outcomes,” including regularly testing vision, testing hearing, and educating parents about problems to watch for.

In an eloquent essay, on the American Academy of Pediatrics website, Dr. Ysern discussed practicing pediatrics in what he called, “the times of Zika,” with his patients and his community overshadowed by a sinister epidemic which touches many aspects of their lives.

We’re tracking the spread of a virus across the map, followed by a generation of babies born with their nervous systems irrevocably damaged, their lives and potential scripted prenatally by the infection. We know they will need extra care over their whole life spans.