Negative results should have a venue for publication, and an unbiased collection of all results will have considerable value when meta-analyses are conducted (Romero et al., 2002). There has been considerable concern about the lack of ability to replicate the findings of gene-disease association studies. “The literature is full of reports of genetic linkage or association that do not hold up under scientific scrutiny.” “Replication of findings remains a critical step to confirming the presence of such effects” (Vogler and Kozlowski, 2002).

Nevertheless, progress is being made in defining quality standards for genetic-epidemiological research. On the basis of the findings presented at the Human Genome Epidemiology workshop, a checklist for the reporting and appraisal of studies of the prevalence of genotypes and studies of genedisease associations was developed (Little et al., 2002). This checklist focuses on the selection of study subjects, the analytical validity of genotyping, population stratification, and statistical issues. Use of the checklist should facilitate the integration of evidence from genetic and epidemiological studies of preterm birth (Little et al., 2002). Ongoing evaluation is needed to make sure that such guidelines are refined and are suitable for research on the genetics of preterm birth.

For many years, research on the etiology of preterm birth has primarily focused on demographic, social-behavioral, and environmental risk factors. Until recently, the roles of genetic susceptibility and gene-environment interactions in preterm birth have largely been unexplored. The use of molecular genetic epidemiology represents a promising approach to understanding the role and biological mechanisms of the genetic and environmental factors involved in preterm birth and their interactions in the pathogenesis of preterm birth. New tools for high-throughput genotyping, coupled with very-large-scale population-based studies that use sensitive biomarkers, comprehensive exposure assessment, and advanced biotechnology and analytical strategies, are needed to unravel the complex multiple gene-environment interactions responsible for preterm birth. Understanding these factors and their interactions could lead to major improvements in the diagnosis, prevention, and treatment of preterm birth.