European Birth Cohorts for Environmental Health Research

Article excerpt

BACKGROUND: Many pregnancy and birth cohort studies investigate the health effects of early-life environmental contaminant exposure. An overview of existing studies and their data is needed to improve collaboration, harmonization, and future project planning.

OBJECTIVES: Our goal was to create a comprehensive overview of European birth cohorts with environmental exposure data.

METHODS: Birth cohort studies were included if they a) collected data on at least one environmental exposure, b) started enrollment during pregnancy or at birth, c) included at least one follow-up point after birth, d) included at least 200 mother-child pairs, and e) were based in a European country. A questionnaire collected information on basic protocol details and exposure and health outcome assessments, including specific contaminants, methods and samples, timing, and number of subjects. A full inventory can be searched on www.birthcohortsenrieco.net.

RESULTS: Questionnaires were completed by 37 cohort studies of > 350,000 mother-child pairs in 19 European countries. Only three cohorts did not participate. All cohorts collected biological specimens of children or parents. Many cohorts collected information on passive smoking (n = 36), maternal occupation (w = 33), outdoor air pollution (n = 27)> and allergens/biological organisms (n = 27). Fewer cohorts (n = 12--19) collected information on water contamination, ionizing or nonionizing radiation exposures, noise, metals, persistent organic pollutants, or other pollutants. All cohorts have information on birth outcomes; nearly all on asthma, allergies, childhood growth and obesity; and 26 collected information on child neurodevelopment.

CONCLUSION: Combining forces in this field will yield more efficient and conclusive studies and ultimately improve causal inference. This impressive resource of existing birth cohort data could form the basis for longer-term and worldwide coordination of research on environment and child health.

Key WORDS: birth cohorts, child health, environmental exposures, Europe, review. Environ Health Perspect 120:29-37 (2012). http://dx.doi.org/10.1289/ehp.1103823 [Online 29 August 2011]

It is well recognized that the fetus and infant are especially vulnerable to the effects of environmental risk factors that disrupt developmental processes, due to a) critical windows of vulnerability that occur during the rapid growth and development of organs and systems, b) immaturities in metabolism, and c) greater intake and absorption of noxious agents in children relative to their body weight (Grandjean et al. 2008). Chemical, physical, and biological hazards in the environment may lead to serious health problems at birth and during childhood, ranging from premature birth, low birth weight, and congenital anomalies to respiratory diseases, childhood cancer, learning disabilities, behavioral problems, and possibly even obesity (Trasande et al, 2009; Wigle et al. 2007). The economic and societal costs associated with nonoptimal child health and development are substantial. Furthermore, the effects of exposure to environmental risk factors may manifest themselves throughout a lifetime and even over generations. Common physical and mental diseases in adult life appear to have part of their origin in early life (Gillman et al. 2007; Kuh et al. 2003).

Epidemiological studies worldwide have investigated the role of early environmental contaminant exposures on pregnancy outcomes and child health (Wigle et al. 2007). Many have suffered from biases due to retrospective study designs, surrogate exposure and outcome measures, and incomplete confounder data. Pregnancy and birth cohort studies are ideally suited to improve causal inference in this field, because they are designed to study the impacts of ( early exposures prospectively and at multiple time points during development of the child. Furthermore, birth cohort studies usually collect biological material from mothers and children, enabling the measurement of biomarkers of exposure, early effect, or susceptibility. …