New mums face many challenges after the birth of their child. A huge and complex decision for many is whether to stay at home or go back to work. Half of British mothers go back to work before their child is a year old. Research has begun to focus on the immediate effects of nursery-centred childcare, highlighting raised levels of the stress hormone, cortisol, in such children. Changes in the neuroendocrine networks may result, with long-term consequences for mental and physical health.
Much research on day care influences – nurseries in particular – centre on the apparent downstream effects, the characteristics of school age children. Childrens’ language skills, academic ability, levels of empathy and aggression and the ability to form friendships are the kind of issues under the spotlight.
Now scientists are using neuroendorinology to study infants and toddlers as they are experiencing childcare. Babies and toddlers cannot verbalise their emotions but salivary cortisol levels can be used as a measure of stress. Raised cortisol levels are part of the flight or fright response. An alarming thought perhaps. How can we relate babies’ and toddlers’ nursery lives to the kind of response that was necessary for early man to escape a charging mammoth?
Cortisol levels fluctuate throught the day as part of our natural circadian rhythms. Cortisol is the end product of the hypothalamic-pituitary-adrenal axis (HPAA) in the brain, the system that is involved in our capacity to respond to fear or uncertainity.
Cortisol peaks in the early morning and declines as the day progresses. Babies are born without this diurnal cycle but acquire it during their first year of life. Raised cortisol levels in adults are associated with an increased risk of health problems such as cardiovascular disease and psychiatric disorders.
Children, up to aged 3, in nurseries have been shown to have an increased level of cortisol in the afternoons compared to the mornings. This only occurs on the days they are in childcare. Research that correlates cortisol levels with stress is now focused on how cortisol can program the brain’s HPAA. The concern is that exposure to elevated stress levels may result in lasting changes in the setting and function of the HPAA.
Researchers need to address how levels of cortisol measured at this stage relate to long-term development. Stress, as measured by cortisol levels, may occur in a home enviroment, just as in a nursery, whether the care is from a parent or a nanny. What are the biological effects of staying at home with a nanny who has not bonded with the child? Stress levels at home may be high relative to a well-run nursery.
There is likely to be a dose-response relationship at work here, both in terms of the ‘quality’ of day care, the number of hours and/or days attended and the age the child first attended. If part-time work is possible, this may be the answer, particularly if the days spent at home outweigh those spent in childcare.
The flight or fright response is part of what drives the human race. Getting that balance right is inherent in raising children. Measuring biological markers of stress is just one element of the process and perhaps not one to get too hung up on.
Early years childcare is a vital step in the rearing process but it is only one step. A constant re-adjustment of perspective is required, refocusing on what matters most at different stages of a child’s development.
The nature versus nurture argument also comes into play here. Some children are inherently more suited to a nursery environment. Many mothers will realise, albeit retrospectively, that one-to-one parental care at home is/was best for that child. The nature versus nurture influence is not simply a matter of measuring cortisol levels.
Deciding on the right form of care for a very young child is a thorny and highly personal issue. Nursery can have many positive benefits ranging from encouraging unfussy eating to learning how to interact with other children.
Gut feeling, family finances and career plans are likely to be the most important driving forces behind any childcare decisions. And perhaps a growing realisation across medical, scientific and parenting experts that the moulding and development of young brains is a subtle process that continues all the way through childhood and adolescence.