Prevalence of infertility: international data and problems of measurement.

This paper discusses the various research options open for measuring the prevalence of infertility. National and regional surveys are both population-based studies but with different methodological approaches. National surveys give information on the various parameters of a couple's reproductive life and indicate the main trends concerning infertility. They give an approximate estimate of the prevalence of infertility, depending on the validity of the collected data. Regional studies can measure the prevalence, incidence, causes and distribution of primary and secondary infertility. When properly carried out, i.e., when the census of infertile couples can be considered as almost exhaustive and when the population studied is representative of the general population, their results can then be inferred on a national scale. Epidemiologists working in infertility have a duty to design appropriate methodologies, thus making public health policymakers aware of the aspects and implications of different types of infertility surveys.