The biology of early health and development illustrates how complex interactions among genes, environmental conditions, and experiences produce either positive adaptations or negative disruptions in basic biological systems—with lifelong consequences for both physical and mental health. There is much that society can do to ensure that children’s environments provide the conditions that their biological systems need to produce positive health outcomes.
Three critically important foundations invite careful scrutiny:
- a child’s environment of relationships;
- the physical, chemical, and built environments; and
- sound and appropriate nutrition.
Creating a Stable and Responsive Environment of Relationships
Human infants are unique among all species in their prolonged period of extreme dependence on adult care and protection for their survival and healthy development.
The care that infants receive, whether from parents, extended family members, neighbors, or child care professionals, lays the groundwork for the development of a wide range of basic biological processes that support emotion regulation, sleep-wake patterns, attention, and ultimately all psycho-social functioning.
Stable, responsive, and nurturing care-giving early in life is also associated with better physical and mental health, fewer behavior problems, higher educational achievement, more productive employment, and less involvement with social services and the criminal justice system in adulthood.
In biological terms, a child’s environment of relationships can affect lifelong outcomes in emotional health, regulation of stress response systems, immune system competence, and the early establishment of health-related behaviors.
A child’s environment of relationships can affect lifelong outcomes in emotional health, regulation of stress response systems, immune system competence, and the early establishment of health-related behaviors.
Thus, supports for families and appropriate training for providers of early care and education across all types of care, including informal arrangements as well as established centers, can improve health outcomes throughout the life course as well as enhance the current quality of life for young children and the adults who care for them.
One important way in which responsive care-giving has long-lasting effects on physical and mental well-being is through the formation of strong, positive bonds between young children and the important adults in their lives.
Securely attached infants show more positive emotion and less anxiety in early childhood and have an easier time establishing relationships with teachers and peers at school.
Attachment patterns develop over the first few years of life and can influence mental health and psychological functioning throughout childhood and the adult years.
Caregivers struggling with overwhelming problems such as depression may be unable to be sufficiently responsive to a young child during that early period when the foundations of attachment relationships are developing.
This lack of consistent responsiveness disrupts what has been called the “serve and return” interaction between infants and adults that is fundamental to the development of healthy brain architecture.
When appropriate responses are missing, this can lead to a range of poor outcomes, including physical and mental health problems later in life.
Effective self-regulation and sleep cycles.
Another way in which the care-giving environment affects the health of young children is the extent to which the consistency, quality, and timing of daily routines shape their developing regulatory systems.
Beginning in the earliest weeks of life, the predictability and quality of these experiences influence the most basic biological rhythms related to waking, eating, eliminating, and sleeping.
For example, infants who are exclusively breast-fed through about 3 months of age ingest levels of nutrients and hormones that reflect the mother’s circadian rhythm (i.e., her 24-hour sleep-wake cycle) and appear to assist in establishing better sleep patterns and sleep efficiency.
Early experiences stimulate a wide variety of nerve transmissions that activate different parts of the brain and other body systems.
When positive experiences are repeated regularly in a predictable fashion, the complex sequences of neural stimulations create pathways that become more efficient (i.e., “neurons that fire together wire together.”)
For example, infants who learn that being soothed and comforted occurs shortly after they experience distress are more likely to establish more effective physiological mechanisms for calming down when they are aroused and are better able to learn to self-soothe after being put down to sleep.
In contrast, when eating and being put to bed occur at different times each day and when comforting occurs unpredictably, the organization and consolidation of sleep-wake patterns and self-soothing responses do not develop well, and biological systems do not “learn” healthy routines and self-regulation.
This finding highlights the importance of secure, stable housing with quiet and predictable sleeping areas for babies. Although children differ in how much sleep they require, inadequate amounts lead to disruptive behavior problems, diminished cognitive performance, and greater risk for unintentional injuries.
Growing evidence also suggests that poor sleep is associated with obesity in later childhood and early adulthood.
Given that babies’ internal clocks do not initially differentiate day from night, how and when they are put to sleep shapes their development of sleep-wake rhythms.
Healthy stress response systems
Just as early experiences affect the architecture of the developing brain, they also shape the development of other biological systems that are important for health. For example, responsive care-giving plays a key role in the normal maturation of the neuro-endocrine system.
A wealth of animal research that is now being replicated in humans demonstrates that care-giving behavior also shapes the development of circuits that regulate how individuals respond to stressful situations.
Specifically, variations in the quality and quantity of maternal care that a mother received in her own early life can affect how genes are turned on or off in her own offspring.
Genes involved in regulating the body’s stress response are particularly sensitive to care-giving, as early maternal care leaves a signature on the genes of her offspring that carry the instructions for the development of physiological and behavioral responses to adversity.
That signature (known as an epigenetic marker) is a lasting imprint that affects whether the offspring will be more or less likely to be fearful and anxious later in life.
Consequently, early overloading of the stress response system can have a range of adverse, lifelong effects on learning, behavior, and both physical and mental health.
That said, effective programs are available that prevent specific types of stress-inducing events, such as physical or sexual abuse, and that provide successful treatments for children experiencing high levels of anxiety or chronic fear.
Regulatory mechanisms that manage stress also influence the body’s immune and inflammatory responses, which are essential for defending against disease.
Young children cared for by individuals who are available and responsive to their emotional and material needs develop well-functioning immune systems that are better equipped to deal with initial exposures to infections and to keep dormant infections in check over time.
Some protections, such as maternal antibodies, are passed directly from mother to fetus through the placenta or from mother to infant through breast milk. These protections confer important passive immunity until the infant’s own antibody response is developed.
Thus, care-giving practices such as breastfeeding not only provide important opportunities for social bonding but also help the baby develop a more competent immune system.
Conversely, inadequate care-giving and limited nurturance very early in life can have long-term (and sometimes permanent) effects on immune and inflammatory responses, which increase the risk of chronic impairments such as asthma, respiratory infections, and cardiovascular disease.
Learned health-promoting behaviors
Another way in which early care-giving practices matter is the extent to which young children develop behavioral routines and patterns that influence long-term health trajectories.
These early behaviors include a wide variety of domains:
tooth brushing, television viewing, routine levels of physical activity, and risk-taking behaviors, among many others. One example is the type, amount, and frequency of foods offered to infants and toddlers, which together shape the processes that affect their taste and texture preferences and their developing dietary likes and dislikes. Increasingly persuasive scientific evidence shows that early learning of both food preferences and routine levels of physical activity affect the risk for obesity.
Center on the Developing Child (2010). The Foundations of Lifelong Health Are Built in Early Childhood. Retrieved from