Gestational age and birth before 40 weeks of gestation

Abstract

The relationship between gestational age at birth and later cognitive, educational and behavioural problems is well described but trying to work out relevant influences on these important outcomes is so important. Parents struggle to make wise choices for their children and, particularly over the key milestone of going to school and supporting their child in education. To this we should perhaps add the planning of birth near term. The data presented from the Millennium Cohort Study add to the information we have on special educational needs (SEN) in relation to gestational age. Births were grouped into very preterm (<32 weeks), moderate preterm (32–33 weeks), late preterm (34–36 weeks), early term (37–38 weeks) and by week thereafter. The data show nicely the increased risk of SEN, of need for educational statement and of SEN in multiple areas for births <32 weeks. The relationship between gestational age and SEN risk in larger samples has been shown to be exponential, rising rapidly with increasing immaturity to reach 40%–50% for births at 24 weeks of gestation. Thus, the use of broad groups—necessary here because of the reduced numbers at each week—probably hides the true picture at extremely low gestational ages as we and others have shown. Given the complexity of neurocognitive morbidity among this vulnerable group, it is unsurprising that there is increased risk of having an educational statement (a legal description of needs in the UK) and of having SEN in multiple domains. So far so good. The finding of increased risk (although at a much lower rate) of SEN among those born at early term age may at first sight seem worrying. These findings confirm those of the study from Scotland of whole population risk, where a similar increase in risk of SEN was shown with a nadir at 41 weeks. Such is the difference in numbers born at each gestational week, however, that the attributable fraction of SEN contributed by birth at 24–27 weeks was only 0.005 compared with 0.016–0.020 for each week between 37 and 39. Thus, in population terms this small risk increase for early term births is much greater than that contributed by extremely preterm children. The ability of the present study to separate out planned and unplanned delivery could shed light on the potential of prevention but the relative risk of having any SEN or multiple SEN was actually elevated after spontaneous labour, suggesting that prevention simply on the grounds of reducing planned delivery rates was unlikely to improve this risk. This is reassuring. One of the challenges for paediatric medicine is that we look after developing children who are at educational risk because of their underlying conditions. Thus, it is so important that we look beyond disability when we describe the outcomes for our patients. The excellent reappraisal of the definition of cerebral palsy to align with the International Classification of Functioning, Disability and Health: Children and Youth Version developed by the WHO in 2007 teaches us to look more widely than simple function outcomes and points to the complexity of understanding outcomes in their own context. Sullivan and colleagues have recently described such outcomes in relation to prematurity. Educational outcomes provide a facet of understanding how children cope in our society and national data are a key aspect of assessing this. Health and educational data need to be combined to provide an important resource for clinical and education planning and for research.