Published September 2010
The number of premature births is increasing; currently 7-9% of babies are born under 37 weeks. In the 1960s, babies born this early would not have survived. Advances in modern neonatal medicine in the last 15 years have meant that babies born 17 weeks early (at 23 weeks gestation) can survive. Looking after these babies, however, can be very expensive.
Professor Dieter Wolke is currently carrying out three major studies involving large population samples, to get a better idea about the consequences of being born prematurely. For 20 years or so the focus has been on the physical consequences of being born too early, including blindness, deafness and cerebral palsy. Recently psychologists have begun working alongside medics to look at the cognitive and behavioural outcome, as well as the general quality of life for these children as they grow into adults.The neonatal intensive care costs for extremely preterm babies are around £150,000 and up to 70% may require special needs support in school and ongoing intervention into adult life. Premature babies now make up a larger sample of the population due to the increase of preterm births and the rise in survival rates. What are the costs for the children, their families and society? Can we afford to revive all of these very young babies? Compared to the UK, countries like Holland and Switzerland are less likely to offer intensive care to children born 16 weeks early or less.
One of the three research projects is a longitudinal study in Bavaria, which follows very preterm babies from birth up to 26 years of age. The study is due for completion in 2015 but findings already highlight the serious cognitive damages caused by an early birth and support previous studies. Around 25% experience major cognitive deficits. Often these children struggle at school due to attention problems and have lower quality peer relationships. The cause of many of these psychological problems stems from the less developed and sometimes damaged brain. At 24 weeks gestation the brain consists of only white matter. It is during the following 16 weeks, in full term pregnancies, that the grey matter and cortex is formed. The interruption in brain development, and continuation of its formation extra-uterine, causes the neuronal cells of the brain (the axons and dendrites) to form abnormal projections and pathways. MRI scans show that the end result is a different brain to those of normal full term pregnancy and it is this that is causing cognitive problems.
The chance of developing cognitive defects differs according to the stage of prematurity: of those born extremely preterm (under 26 weeks), 45% will have cognitive deficits; of those under 32 weeks, 25% will display cognitive problems; and although babies born moderately preterm (up to 36 weeks) have a lower chance of developing psychological problems, there is still a higher risk than in full term babies. Worryingly, even those born in week 37 or 38, just 2 – 3 weeks early, have a slightly increased chance of cognitive defects.
There are two types of intervention that have been researched and tested. One involves children receiving specialist daycare and advice for parents on optimal social interaction. The other tries to reduce handling and encourages gentle care to reduce and prevent further brain and organ damage that could cause distress and disability. Unfortunately, none of these interventions have shown lasting positive effects into school age and, more shockingly, those born under 32 weeks show little positive response to intervention and no reduction in cognitive deficits. It could be that biologically, up to 32 weeks, the brain is simply not able to benefit from these environmental interventions.
In a health service that has limited resources, Prof Wolke argues, somewhat controversially, that babies born over 32 weeks should be the health service's priority. At the moment, very preterm children only make up 1% of the population, whereas moderate preterms make up 6 – 7 %. More significantly, moderately premature babies are currently discharged from hospital with the belief that they are at low risk of developing problems, and therefore do not receive the support that they and their family need during their development. Despite studies showing that these children are most likely to benefit, public healthcare efforts are mismatched, focusing on very preterm babies who are less able to benefit from these interventions.
Scientific and medical research needs to continue to understand the consequences of being born preterm, and ultimately develop preventative strategies to reduce and avoid premature births and induce healthy, normal, fullterms; possibly benefiting both the economy and society.
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Prof Wolke is a professor in the Department of Psychology and Division of Mental Health & Wellbeing at Warwick Medical School). His main research interests include developmental pathways leading to developmental psychopathology; social and emotional development; especially school and sibling bullying; the development of biological at risk children (very preterm children) and infant regulatory problems (crying, feeding, sleeping) and parenting. His current research projects include 'Managing the Link and Strengthening Transition from Child to Adult Mental Health Care' (01/02/2014 - 31/01/2019) and 'Understanding Society and the UK Longitudinal Study' (01/04/2013 - 31/12/2018).