We talk often in pediatrics about the importance of early identification and early treatment of autism spectrum disorder, with its hallmark issues of social communication problems and restricted repetitive behavior patterns. “Early” means paying particularly close attention to the behavior and development of children between ages 1 and 3, and checking in with their parents about any concerns.

But what does that mean for young children who have now spent half their lives — or more — in the special circumstances of the pandemic?

Dr. Heidi Feldman, a professor of developmental and behavioral pediatrics at Stanford University School of Medicine, said, “We don’t know what the impact of one year of very restricted social interaction is going to be on children.” Some of the behavior patterns that children are showing now may be the result of these strange living conditions, or they may reflect stress, trauma and the social isolation that many families have experienced, she said.

Dr. Feldman said that first-time parents who have been operating in the increased isolation of the pandemic may have very limited context for appreciating where their child’s behavior falls. They’re missing the input they might usually get from teachers and child care providers.

Dr. Eileen Costello, a clinical professor of pediatrics at Boston University School of Medicine and chief of ambulatory pediatrics at Boston Medical Center, said, “Especially for the really little ones, the only eyes that are on them are their parents’. They’re not seeing uncles and aunts and cousins, not in preschool.”

Dr. Costello and I are co-authors of the book “Quirky Kids: Understanding and Supporting Your Child With Developmental Differences.” We use the word “quirky” to encompass children whose development does not follow standard patterns, whether or not they fit the criteria for a specific diagnosis. Some of these children will accumulate several different diagnoses as they grow and change — and as different demands are made on them in terms of academic performance and social life — and others will never fit the criteria for any specific formal diagnosis.

Dr. Adiaha Spinks-Franklin, a developmental behavioral pediatrician at Texas Children’s Hospital and an associate professor at Baylor College of Medicine, said that because parents right now are at home more, sometimes they are more likely to notice unusual or concerning patterns — repetitive behaviors, or communications problems like echolalia, in which a child repeats words. This can be completely normal, and is in fact part of how children learn to talk, but it can be concerning if it’s the major part of a child’s language as the child grows. By the age of 2, children should be saying lots of their own words.

When parents — or teachers or doctors — do have concerns, getting a developmental assessment done has its own complexity in the pandemic.

Catherine Lord, a professor of psychiatry and education at the University of California, Los Angeles, said, “I’m doing diagnoses right now in my back yard, which is insane.” But with the protective gear that would have to be worn at the hospital, she said, “we look like we’re from outer space,” and could be too intimidating to small children.

Dr. Lord said. “We do remote interviews with parents, we try to see videos of the kid, then have them come — we have a big back yard.” And they continue to use the Zoom technology, even across the yard.

The standardized assessment for autism spectrum disorder can’t be done masked, because it depends on interpreting the child’s expressions and observing reactions to the examiner’s facial expressions. Dr. Lord said there is a shorter version that children can do with their parents — everyone unmasked — while the clinicians watch without being in the room. This may not be as accurate — researchers are still analyzing the data — but they are hopeful that it will be helpful in many cases.

“When we see kids in clinic, we have to be masked, and if they’re over 2, they have to be masked,” Dr. Feldman said. Earlier in the pandemic, a family that was convinced that their child had autism came to the clinic. “This kid had not seen anybody other than his parents and had not been anyplace other than his home — he was so terrified — the in-person visit was very, very hard.” They used a room with a one-way mirror, so the parents could be alone with the child, and could take their masks off, but “even with that, he had such a hard time settling down.”

Dr. Lord was the lead author on a review paper on autism spectrum disorder published in Nature Reviews in 2020. She emphasized the importance of early diagnosis so that children can get early help with communication: “Kids who are going to become fluent speakers, their language starts to change between 2 and 3, and 3 and 4, and 4 and 5,” Dr. Lord said. “We want to be sure we optimize what happens in those years and that’s very hard to do if people are stuck at home.”

She recommended that parents request the free assessments that can be done through early intervention, in many cases now being done remotely.

Developmental assessments can include remote visits. “We have gotten quite good at doing telehealth evaluations,” Dr. Feldman said. “We get the kids in their own environments and their own toys, we get to see what they do at home.”

“Sometimes making the diagnosis of autism over telehealth in a very young child is incredibly challenging,” Dr. Spinks-Franklin said. “Families that don’t have access to consistent reliable high-speed internet are also impacted — a video visit may not be possible or may be interrupted.”

Even before the pandemic, many families faced long waits to get those developmental assessments. “Those who are vulnerable already are always going to be more severely affected — families who already had more limited access to primary care providers or are underinsured or uninsured already had a harder time,” Dr. Spinks-Franklin said.

Now, she said, the pandemic is placing those families even more at risk, because of the likelihood of economic hardship from jobs loss, underemployment or lost health care benefits. The disparities are exacerbated, and the chance of getting to the right clinic and the right health care professional go down.

Right now, because families are isolated or may not have good access to medical care, neurodevelopmental problems may be being missed in these critical early years, when getting diagnosed would help children get therapy. On the other hand, some children who don’t have these underlying problems and are just reacting to the strange and often anxiety-provoking circumstances of pandemic life may mistakenly be thought to be showing signs of autism.

Parents and even doctors may worry about autism spectrum disorder in children who have attention deficit hyperactivity disorder or anxiety, and who are being seen in unusual situations — in a parking lot, for example. “I’ve been undoing diagnoses,” Dr. Lord said. “It’s not surprising that a kid is looking a bit less relaxed.”

Dr. Spinks-Franklin said that the pressures of the pandemic may act on children as other stresses do, and show up as more extreme behavior, such as more frequent tantrums or increased irritability.

“All that bounces is not A.D.H.D.; all that flaps is not autism,” Dr. Spinks-Franklin said.

What Parents Can Do

To understand whether a child’s extreme behavior represents chronic stress and increased frustration related to the hardships that families are living through, or is a sign of a neurodevelopmental disorder, it’s important to figure out whether these behaviors were present before the pandemic, Dr. Spinks-Franklin said.

If parents have concerns about a child’s development or behavior, a good place to start is to talk the question through with the child’s primary care provider, who can also review the record with the parents and talk about the child’s early developmental course.

If parents still have concerns, it’s reasonable to request a referral for a full developmental assessment. Early intervention, a federally mandated program, offers help and therapy if a child seems to be significantly delayed in any developmental domain, but does not make diagnoses.

Some developmental markers reflect a child’s early progress with speech and language, and with social interactions. The following are adapted from “Quirky Kids.”

• A baby babbles by 6 months, and the babble increases in complexity

• By 9 months, a baby responds to his or her name

• By 15 to 18 months, a child can say some words and follow simple directions

• By 18 months, a child can put two words together

• By 2 ½ to 3, a child can speak in simple sentences with some fluency and inflection — a question sounds like a question

• By 4 months, babies make eye contact and respond with social smiles

• By 1 year, they can point to show interest, and wave goodbye

• From about 2, they respond to other children and can interact in games with some back-and-forth