A review of early childhood studies.

The Lifeways Cross-Generation Cohort Study was $ rst established in 2001 and is a unique longitudinal database in Ireland, with currently over three and a half thousand family participants derived from 1124 mothers recruited initially during pregnancy, mainly during 2002. The database comprises a) baseline self-reported health data for all mothers, a third of fathers and at least one grandparent b) clinical hospital data at recruitment, c) three year follow-up data from the families’ General Practitioners, and d) linkage to hospital and vaccination databases. Data collection for the $ ve-year follow-up with parents is underway, continuing through 2007. Because there is at present no single national/regional health information system in Ireland, original data instruments were designed to capture data directly from family members and through their hospitals and healthcare providers. A system of relational databases was designed to coordinate data capture for a complex array of study instruments and to facilitate tracking of family members at di& erent time points. Introduction There is renewed interest world-wide in birth and childhood longitudinal cohort studies as knowledge grows about the importance of early life in# uences on long-term health and well-being and the extent to which children may be in# uenced by the social and biological characteristics of their parents and grandparents. The Lifeways Cross-Generation Cohort Study is a longitudinal study established in 2001-2 as part of the Health Research Board-funded Unit for Health Status and Health Gain work programme. The study is part of an international network of longitudinal studies established around the Millennium period and was developed in the context of the European Science Foundation funded Social Variations in Health Expectancy in Europe international research programme ( http://www.uni-duesseldorf.de/health/ ). The original design has expanded to implement 4 principal data collection phases in the timeframe 2000 to end of 2007. Though much is now known about such early life in# uences from evidence in other countries, very little was known about the impact of social variations on health status in Ireland, particularly important given the extent of economic transition in the country and virtually no longitudinal datasets exist. Few datasets anywhere include more than one generation of the same family. Accordingly, the overall objectives of the Lifeways Cross-Generation Study were: 1. To record the physical and psychological health status and socio-economic circumstances of individuals at birth, during early childhood, early adulthood and early middle age in Ireland, and 2. To follow them prospectively in order to measure their changing health status initially over a $ ve year period and to assess the extent to which health status relates to social circumstances. By collecting data at four phases over a six year period, the study provides multiple facets by which to assess the extent to which health status relates to social circumstances. Methods It was planned to recruit at least 1000 families over a one year period, that is the expectant mother at $ rst maternity hospital booking visit, with a special focus on those general medical services eligible (medical card holders), her infant at birth (the proband), her partner if agreeable, and at least one living grandparent. Two representative regions were chosen, one urban, one rural, and within those regions two major hospitals providing maternity services were selected for sampling and agreed to participate. In the West of Ireland, University College Hospital Galway (UCHG), provides services for both urban and rural populations and in Dublin, on the East coast, the Coombe Women’s Hospital is one of the busiest maternity hospitals in Ireland with over 7,000 babies born annually. Ethical approval was obtained prior to the study’s commencement in both hospitals and from the ethical committee of the Irish College of General Practitioners. The full cooperation of the maternity units in both hospitals was secured with permission granted for research midwives to be present at ante-natal clinics to recruit expectant mothers for the study, and agreement to provide electronic data $ les related to the pregnancy, labour and birth records from the hospital information systems. Sample size estimates were based on anticipated signi$ cant di& erences, according to medical services eligibility or not, of the following outcome measures: uptake of the 3 in 1 vaccine, option to breastfeed, smoking status of adult participants and annual rates of episodes of health care utilisation. While major outcomes such as inter-current illness, death and cause of death were also to be recorded it was not anticipated that any signi$ cant patterns would emerge by the end of the $ rst $ ve years, though it was an aspiration to continue the cohort for a 20 year period ultimately. There are four time points for collection of data (see Figure 1): baseline questionnaire in 2001 (Phase 1) and birth records in 2002 (Phase 2), follow-up of the full cohort in 2005 (Phase 3) and a fourth time point will be added in 2007 (Phase 4). Phase 1 of the study began when consent was obtained from the expectant mothers who were 14 to 16 weeks pregnant and attending their $ rst antenatal visit (booking visit) at the maternity hospital. The research nurses initially explained the study face-to-face with the women at the clinic, and answered questions as to what their participation would entail over the years. The expectant mothers were then given a lea# et to take home explaining the aims and objectives of the study and the self-completion questionnaire. If agreeable to participate they contacted the study team by telephone and returned the completed questionnaire, the written informed consent and contact details for follow-up at the birth of the baby. To enable the cross-generation recruitment, each mother was also asked to provide the names and contact details for the baby’s father, and up to four of the grandparents. A total of 1124 women were recruited in Phase 1. The objective of Lifeways was to recruit as many as possible of consecutively approached women. The cohort was never necessarily intended to be representative of the general obstetric population in Ireland at the time, since the focus was on longitudinal follow-up and within-cohort comparison and the commitment anticipated for the project was high given the number of family members involved. Nor was every pregnant woman approached during the calendar year as sta ng levels, with one part-time nurse midwife in each hospital site, did not permit full coverage of every ante-natal clinic. It was decided at the outset to exclude mothers born outside Ireland as the study was unlikely to be powered to allow for meaningful sub-group analyses of this kind. Data from the annual reports of 3