A nanny doesn't just "keep an eye" on your child while you're away. She spends many of the hours that matter most in a child's life with them. To understand why, it's worth looking at what science tells us about the early years.

The early years build the foundation

According to the Center on the Developing Child at Harvard University, more than one million new neural connections form every second in the first years of life, and the brain is built gradually, from the ground up. The World Health Organization describes the period from pregnancy to age 3 as the most critical, because this is when the brain grows faster than at any other time.

The "serve and return" that builds the brain

Harvard researchers describe a simple mechanism called serve and return: the baby babbles, points or cries, and the adult responds with a look, words or a hug. Each such exchange builds and strengthens connections in the brain that are essential for communication and social skills. The human brain, they write, expects this back and forth game.

The opposite also matters. When an adult's responses are inconsistent or absent, development can be disrupted and the body activates a toxic stress response. Supportive relationships with caring adults act as a buffer against this stress.

The five components of care

The Nurturing Care framework, developed by WHO, UNICEF and the World Bank, describes five interconnected components that every child needs:

  • good health
  • adequate nutrition
  • safety and security
  • responsive caregiving
  • opportunities for learning

Responsive caregiving, meaning the caregiver's ability to notice, understand and respond to a child's cues promptly and appropriately, is considered the foundational component, because anyone who has it can better support the other four. The same framework stresses that every interaction, or the lack of one, contributes to brain development, and suggests making the most of daily routines for talking, playing and reading.

All areas of development

The US CDC tracks developmental milestones in four areas: social and emotional, language and communication, cognitive (learning, thinking, problem solving), and movement and physical development. A good nanny works on all four within the same day: at the playground, at the table, during storytime, while handling a squabble with a sibling.

Play and reading

The American Academy of Pediatrics describes play as "brain building" and key to what are known as executive functions, as well as a buffer against the negative effects of stress. For reading, the AAP recommends shared reading from birth and at least through kindergarten, because it builds the foundation for social-emotional, cognitive and language development. It also notes that digital books don't offer the same kind of interaction.

Why stability matters

A review in the journal Biological Psychiatry: Global Open Science (Luby and colleagues, 2022) concludes that the consistent availability of at least one primary caregiver is of central importance, and that sensitive, responsive care is critical for behavioral, emotional and cognitive development. The organization ZERO TO THREE, writing about childcare settings, puts it simply: people are not interchangeable, and when a caregiver changes, relationships have to be built from scratch.

That's why, when choosing a nanny, it's worth looking not only at qualifications, but also at whether this person can stay, become a stable part of the child's life, and respond to them in the same way every day.

Sources