1 Research Centre for Reproductive Health, Department of Obstetrics and Gynaecology, University of Adelaide, Adelaide, Australia
1 To whom correspondence should be addressed. michael.davies{at}adelaide.edu.au
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Abstract |
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Key words: terminology/fecundability/fertility
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Introduction |
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Given extensive literature in the social sciences that discusses the use of language in constructing commonsense and expert understandings, the issue of ambiguity in definitions of infertility needs to be considered in broader perspective.
The use of the terms infertility and subfertility create a medically and socially liminal state in which patients hover between reproductive capacity and incapacity (Sandelowski and de Lacey, 2002). One view is that this linguistic grey zone is confusing and unhelpful in the clinical application of medical knowledge where predictive values would enhance advice that maximizes the chance for spontaneous pregnancy and thereby minimizes the use of invasive and expensive procedures (Habbema et al., 2004
). To achieve this, Habbema suggests a strategy of summarizing statements from fertility investigation reports into one of three types: (i) descriptive or observational statement; (ii) diagnostic or causal statement; (ii) prognostic or predictive statement.
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The social context of fertility |
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Further, the problem of ambiguity of terms is added to by infertility being culturally located not in individuals as is presupposed in the model offered by Habbema, but between them (Sandelowski and de Lacey, 2002). In other words, infertility as we understand it in the context of assisted conceptive technologies is related more to sexual or reproductive partnership (involving several participants possibly) than it is to predictive individual biology.
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Unteasing existing distinctions |
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It is necessary to commence with some definitions.
Broadly speaking, fecundity is the biological capacity for reproduction, while fertility is the actual production of offspring (Wood, 1989). In addition to reproductive capacity, a further element required for reproductive success is exposure to the semen. Hence, we can use the term fecundability to define the monthly or cycle-wise probability of conception for a couple that is sexually active, not using contraception and capable of achieving pregnancy. This definition adopted by Wood was developed 80 years ago (Gini, 1924)
. For the purpose of explaining this concept to patients, fecundability can be operationalized as the likely waiting time to pregnancy.
Wood then forms the further distinctions. Total fecundability is defined as the maximal underlying monthly or cycle-wise probability of conception, and which cannot be ascertained in a free-living population due to limitations in detecting very early pregnancy loss that distort calculations of conception rates. Hence, it is common in fertility research and clinical practice to employ the concepts (if not the terms) of apparent fecundability, which is the monthly or cycle-wise probability of conception using a particular technology to detect a pregnancy. Finally, effective fecundability is the monthly or cycle-wise probability of conception that actually results in a live birth. As noted, we cannot observe total fecundability, as we do not have the technology for continuously monitoring pregnancy. However, in frequently observed clinical populations, apparent fecundability may serve as a reasonable approximation of total fecundability.
Within this broad framework, fertility is the actual production of live offspring (Last, 1988). Fertility is a categorical outcome that is contingent on a series of biological and social preconditions. It can be expressed as a ratio or a rate where the denominator is the number in the population within a normal child-bearing age. Infertility is simply the absence of offspring among that reference group. Infertility is not a disease state and alone conveys nothing of aetiology. Infertility defined as the simple absence of offspring is commonly the product of active decision-making and contraceptive practices. It is a state that is increasingly both desired and managed, as reflected in the rising maternal age at first birth and smaller family size in the Western world.
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Relocating infertility with regard to social roles |
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For the purposes of developing terms that are of broad applicability to demographers, biologists, clinicians and patients, it is important to maintain the understanding that an infertile population in clinical care is unrepresentative of the entire population with regard to the significance of infertility. It is illustrative to consider fertility within an existing disability framework. The World Health Organization (1980) has a model that expresses aspects of health from the individuals point of view. The model uses three categories to describe disturbances in health:
Hence, impaired fecundability can have the disabling consequence of infertility. However, infertility is not necessarily a handicap as it may convey no disadvantage or perceived adverse consequences, depending upon cultural expectations. Returning to particular examples, we can now see that infertility contains a compression of meaning within a language group characterized by a common interest. For the couple who are managing their fecundability through contraception, and thereby their fertility, there may be no handicap associated with infertility. Similarly, for a child, the status of infertility is normal and within the biological and social development of the child. By extension, the post-menopausal woman may not necessarily associate infertility with disability. Whether infertility becomes problematic depends upon the perceptions of those affected and their role expectations. The role expectations of others also plays a part in debates over the appropriateness of treatment, for example, among women who may be near the age at which fecundity declines to zero, as there can be a conflict between the disabling consequences for the infertile patient compared to established age-specific social roles regarding the age of parents. Hence, the infertility may have been arrived at by quite different paths, or conversely, the meaning of a status of infertility is contingent on a range of contextual features that reflect our role expectations and intentions. A simple schematic (Figure 1) can demonstrate that not all infertility is the product of diseaseindeed the majority of paths exclude a disease entity. Clinical concerns deal with the subpopulation of individuals where there is impaired fecundability combined with unintentional infertility, or in the event of sterilization, where it is no longer desired.
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Summary |
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References |
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Habbema J, Collins J, Leridon H, Evers J, Lunenfeld B and te Velde E (2004) Towards less confusing terminology in reproductive medicine. A proposal. Hum Reprod 19,1497501.
Last JM (1988) A Dictionary of Epidemiology. 2nd edn, Oxford University Press, New York, USA, pp 1141.
Sandelowski M and de Lacey S (2002) The uses of a disease: infertility as rhetorical vehicle. In Inhorn M and Van Balen F (eds) Interpreting Infertility: Childlessness, Gender, and the New Reproductive Technologies in Global Perspective. University of California Press, Berkeley.
Wood J (1989) Fecundity and natural fertility in humans. In Milligan SR (ed) Oxf Rev Hum Reprod. Oxford University Press, Oxford, UK.
World Health Organization (1980) International Classification of Impairments, Disabilities, and Handicaps: A Manual of Classification Relating to the Consequences of Disease. World Health Organization, Geneva.
Submitted on August 4, 2005; accepted on June 16, 2005.
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