Tracking the health, educational and economic impact of gestational age at birth: a longitudinal record linkage study (TIGAR)

Background
A typical pregnancy lasts about 40 weeks and babies born before 37 weeks of pregnancy are classified as premature or preterm. These babies have a higher chance of dying and those that survive are more likely to have health and developmental problems in childhood and adulthood. Children who are born early are also more likely to have special educational needs, or may not perform as well as their classmates in their school tests. Recent research suggests that even those babies who are born a few weeks early may have more problems in childhood compared with those who are born after a full term pregnancy.

Studies of the long term impact of prematurity need to include a large number of children (at least 100,000). There have been studies as large as this, but their findings may not be relevant to children born today. For example, they are based on children born in the 1960s-90s who experienced different newborn care to babies born today. Also, most of the studies are based on Scandinavian or American children, who will have experienced different health and education systems to children in the UK.

There is a need for a large UK study to assess the health and educational outcomes and costs, associated with preterm birth in a population of babies born in the 21st century.

Aims and objectives
Our aim is to carry out a study on children born in England in 2005-6 and use it to investigate differences in health and education outcomes for children born early compared with those born after a full term pregnancy. Our analysis will determine whether being born early has a larger impact on children who are living in poverty or are socially disadvantaged. We will also measure the costs of prematurity to health and education services.

Methods
The study will include all babies born in England during 2005-2006 (about 1 million) and will follow-up the children through linking together different routine information sources. We will try to obtain data on any hospital admissions or outpatient visits that the children experience until the age of 10, and their school results from national tests which are performed when the children are 5, 7 and 11 years. The school results will also indicate whether the child has special educational needs and what support is given. This information will give us a picture of each child's health and school results, and will enable us to see how much this is affected by being born early.

Two groups will be formed to advise on the project. One group will include relevant experts, stakeholders (e.g. the support group 'BLISS for babies born too soon, too small, too sick') and will include representatives of families affected by premature birth. Another group will provide a user's perspective on all aspects of the project. Members will include families affected by premature birth (e.g. parents of preterm children, and young adults who were born early).

Potential applications and benefits
The results of this study will be made available to the relevant professionals. The results will inform teachers and other education professionals about the type of problems that may occur in children who were born early and what kind of special educational needs support is needed. The results will also assist in counselling of parents about the types of problems that may occur, which will enable them to be more prepared about what to expect and when to seek help from professionals. Our results on the costs associated with prematurity will be helpful to organisations who plan or deliver services in hospital, schools or the community. They will also help ensure that the children who need the most help are identified and given appropriate support. Finally, we will create a resource for researchers who are doing similar record linkage studies, which will describe how we accessed, linked and analysed these large datasets.

Background
Preterm birth (PTB) is a major cause of long term loss of human potential. Survivors of PTB, even those born a few weeks early, have an increased risk of health and neurodevelopmental problems in childhood and adulthood. Studies of long term outcomes following PTB need to be based on large numbers. There have been several large studies of the long term effects of PTB, but their findings may not be generalisable to the current UK population. There is a need for a large UK study to assess the health, educational and economic outcomes, across the whole gestational age spectrum, in a population-based cohort of babies born in the 21st century.

Aims and objectives
Our study will create a longitudinal record linkage study and use it to estimate: the effect of gestational age on health and educational outcomes up to 11 years of age; the trajectories of these outcomes in different gestational age-groups; whether these effects vary according to markers of social deprivation; and the costs to health and education services.

Methods
We will create a national population-based cohort of all live births in England during 2005-2006 (~1 million) with follow-up of children through record linkage of several routine datasets (Hospital Episodes Statistics and the National Pupil Database). The study will include a wide range of health (e.g. all-cause and cause-specific hospital episodes) and educational outcomes which are directly relevant to UK health and education systems. The educational data include not only academic performance (which is an important marker of lifelong attainment and future health), but also the presence and type of special educational need, and what support is given, during the child's primary schooling (age 4-5, 6-7 and 10-11).

Our results will inform the parents and health/educational professionals who care for children born before full-term, and the organisations who plan or deliver services in hospital, schools or the community.

Our estimates of the risks, risk trajectories, effect modifiers and costs associated with birth before full-term will benefit:

i) Those who provide obstetric and neonatal care to those affected by birth before full-term. For example, robust estimates of short and long term effects of birth before full-term on both health and educational outcomes will help clinicians weigh up the potential harms and benefits in the scenario of induction of labour for intrauterine fetal growth restriction. The results will also determine whether the group of preterm babies identified for routine follow-up under current practice is appropriate.

ii) Those who provide education to children born before full-term. Our results will inform education professionals about the nature and developmental change in problems associated with birth before full-term and what kind of special educational needs support is needed. A recent survey suggests that ~90% of teachers feel ill-equipped to support preterm children in the classroom highlighting the pressing need for data to inform educational policy and practice.

iii) Other stakeholders who support families affected by birth before full-term. We have already identified some stakeholders such as 'Bliss' (a charity that supports those affected by preterm birth). Bliss has agreed to support our application. If our project is funded, we will use our networks to identify a wider group of stakeholders in health and education, who can provide input to our project (via the two advisory groups) and ensure that they benefit from our research.

iv) Parents of children born before full-term. The results will assist in counselling of parents about the types of problems that may occur, which will enable them to be more prepared about what to expect and when to seek help from professionals.

v) Those involved in resource planning, policy and service provision (such as neonatal and paediatric healthcare services, public health and education services) and the development of interventions in terms of populations targeted and the content and timing of delivery (for example, whether it is important to focus on children born very preterm, or socially deprived preterm children).

Our methodological resource describing the process and methods for accessing and analysing these datasets will benefit researchers:

i) Applying to access our linked dataset or undertake record linkage of similar datasets. We will help facilitate this process by documenting information about the approvals process, linkage methods and results, data validity and statistical methods. The resource will take the form of a short report which will be made available to interested researchers on request and will be disseminated through a workshop towards the end of our study. We will also feedback our experiences to the newly formed ESRC-funded Administrative Data Research Centres.

ii) Undertaking analysis of our linked dataset or similar datasets. For example, we will share our Stata programs ('do' files) with other researchers so that they can reproduce our data checking, cleaning, recoding, derivation of new variables, and analysis. These programs would be useful to researchers analysing the same variables in our linked dataset, or for researchers who had accessed the individual, unlinked datasets (e.g. NN4B, HES, NPD) or similar datasets (birth records, hospital records or school records for children born in different years). These 'do' files would be shared for free, under licence from the University of Oxford (as with other 'do' files generated by NPEU staff). This requires acknowledgement of the research team if they are used in analyses which lead to publication.