The following is an extract from the cohort profile, published in the International Journal of Epidemiology in 2013:

What has been measured?

The development and health of the children is assessed both from the mother's opinion and from health records.

Information has been collected from the following sources:

Questionnaires to parents and study children

Mothers were personally recruited to the study in the ante-natal clinics soon after the confirmation of their pregnancy. Their partners were also encouraged to participate and both were asked to fill in a series of questionnaires before their baby's birth. When the baby was 6 weeks old three more questionnaires were sent by post, repeated again when the child was 6 months, 18 months, 3 years and 5 years of age. Questionnaires were completed at home and returned to the study headquarters in prepaid envelopes.

Identical questions, designed by an international team of experts, were asked in each study centre, to seek information about the parents' environmental conditions, health, beliefs, attitudes, experiences, lifestyles and upbringing. Questionnaires in infancy asked about the baby's birth, the parents' experiences during that time, their attitudes to the health services, how their babies developed, how they were caring for them and bringing them up. As the children grew older, the questions were more focussed on behaviour and development including aspects of school achievement.

Health records

Details of the clinical course of pregnancy and childbirth were abstracted (with the mothers' permission) from case notes onto detailed proformae. Data concerning the children's development, illnesses, accidents, hospital admissions, consultations and treatment have been obtained from hospital records, updated until the children were 16. Separate questionnaires were completed by health visitors from their own records.

Teacher questionnaires

The primary and secondary school teachers completed questionnaires at ages 7 and 16 concerning the child's ability, and behaviour.

Biological samples

Parents had been asked, when the children were 7, to send samples of their children's hair, nail clippings and milk teeth so that these may be analysed for evidence of exposure to environmental pollutants. Blood samples were collected for analysis of marker substances important in the early identification of disease and for DNA extraction and storage.

Hands-on interviews and examinations

At seven years of age the children underwent a comprehensive series of examinations, which involved detailed testing of their vision, hearing, physical growth, levels of activity and motor co-ordination, blood pressure, lung function, cognitive development, including tests of IQ, reading and non-verbal recognition. Parents were asked to complete a dietary diary recording all food eaten by the study child for three days prior to the date of the clinic appointment; they were then interviewed in regard to details by a trained dietician.

Sub-studies

Studies of a selection of the participants have included:

• Temperature and humidity
• Radon
• Dental examination
• mobile phone effect on children's reaction time.

What are the main strengths and weaknesses?

The study has a number of strengths:

• It covers all eligible women on the Island
• The questions asked are similar/identical to many asked in the ALSPAC study
• It provides unique information concerning an island community
• The island includes two different communities which can be contrasted – the native Manx and the 'incomers' (the population who migrated into the island often for social, political or financial advantage)
• The response rate for particular aspects of the cohort approaches 100%.

The difficulties include:

• Although the response rate has been remarkably good in certain respects, there is a fairly high migration rate off and onto the island
• Overall the numbers are small compared with other major studies, although they are comparable with some cohorts that have shown important results such as the pre-pregnancy cohorts in the Seychelles (n=700) and the Faroe Islands (n≤1000)
• Lack of funding has meant that the data, although collected and keyed are not all edited and documented and ready for universal analysis. This, however, is remediable given appropriate finances.

Can I get hold of the data? Where can I find out more?

A study manual containing details of all data collected, as well as some background to the study has been created, and can be accessed via the downloads section on the right.

Selected data sets are available. Unfortunately, a lack of core funding has dogged this study, and although almost all the data have been keyed, finances are likely to be required to produce a clean documented anonymised file for specific use. Further information is available from the Data Governance Committee at elspac-iom@bristol.ac.uk.