Child Development in the Time of COVID

What are you doing each day to support your child’s developing brain? If you want to be sure your actions lead to positive outcomes, start with this: interact with your child.

It sounds so simple and obvious. Of course you interact with your child whenever you’re together! But, are those interactions as effective as they could be?

In recent years, Harvard University’s Center on the Developing Child identified an especially effective way to interact with very young children—even those who are not yet talking. These “serve and return” interactions (as they were later named) are linked directly to healthy brain architecture.

What is “serve and return”?

Think of “serve and return” as a conversation between two people. Each participant takes cues from the other. When a baby babbles, gestures, talks, or cries, those are serves. When a caregiver responds appropriately with eye contact, words, or a hug, those are returns. When a toddler asks a bunch of questions all day every day, those are serves. When the caregiver attempts to answer the questions, those are returns.

Research has shown that serve and return interactions are what form healthy connections in a child’s brain. These connections are called “white matter” by researchers. White matter is what carries information throughout the brain. It is what helps the child develop social skills, communications skills, and trust.

Patience and observation are the keys to creating effective serves and returns. If you ask a child a question, always wait for a response. Even before the child can talk, they will return your serve through babbling, gestures, and facial expressions. Acknowledge those returns, and imagine aloud what the child might be trying to say. “Oh, you don’t like that rice!” Or, “The music makes you happy, doesn’t it?” This models conversational turns, and boosts a child’s language-processing skills, as well.

When serves aren’t returned

if an adult’s returns to a child are unreliable, inappropriate, or simply absent, the child’s developing brain architecture may be disrupted. This may impair the child’s physical, mental, and emotional health.


If the absence of serve and return interactions persists, the brain doesn’t receive the positive stimulation it needs for healthy development. What’s more, the child’s stress response is activated. As a result, the developing brain is flooded with potentially harmful stress hormones. These hormones can weaken brain architecture. And, they could impact the child’s immune system, among other negative effects.


Many things can account for unreturned serves. A caregiver might not think a young child is capable of sending and receiving serves and returns. Or, the caregiver could be stressed because of financial problems, health issues, or just lack of time. Any of these could cause a breakdown in serve and return interactions.

Child development in the time of COVID

In 2004, “talk pedometer” technology was developed by LENA, a nonprofit company based in Boulder, Colorado. LENA is short for Language ENvironment Analysis. The wearable device records and later delivers detailed information on what a child hears throughout a day. It measures the number of words spoken near the child. And, it records the child’s own language-related vocalizations.

Fast forward to early 2022. Sean Deoni, principal investigator at Brown University’s Advanced Baby Imaging Lab, and his team noticed that children who visited the lab after March 2020 took longer to complete cognitive tasks. “They were not as attentive, or at least not performing as well as we normally have seen,” Deoni said. This prompted them to search for an explanation.

Using LENA devices, they studied two groups of children, ages 12-16 months. One group was born before 2019 (well before COVID first appeared in the United States). The second group was made up of children who were born after July 2020 (in the midst of the viral outbreak).

The researchers found a substantial drop in verbal functioning between the two groups. Infants born during the pandemic produced significantly fewer vocalizations and serve and return moments with their caregivers compared to those born before COVID. And, tests showed that these babies experienced a far slower rate of white matter development as compared to the children born before the COVID outbreak. “Reduced white matter development is associated with reduced cognitive development,” said Deoni.

The researchers also found a significant drop in adult words per hour, and in caregiver interactions with the babies.

What explains these results? It’s suspected that the hardships related to COVID—fear, uncertainty, financial insecurity, and so forth—influenced the number of interactions that caregivers had with children.

The good news is that these serious situations can be corrected in many cases. Quality interactive talk can be integrated into regular routines. Caregivers can learn to identify serves, and respond with consistent returns. And, ideally, children can be buffered from the effects of stress caregivers might feel. In doing so, these children can have great future potential.