Human Reproduction

Hum. Reprod. Advance Access originally published online on June 23, 2007
Human Reproduction 2007 22(9):2471-2475; doi:10.1093/humrep/dem181

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Can assisted reproductive technologies help to offset population ageing? An assessment of the demographic and economic impact of ART in Denmark and UK

S. Hoorens^1,*, F. Gallo^*, J.A.K. Cave^* and J.C. Grant^*

RAND Europe, Westbrook Centre, Milton Road, Cambridge CB4 1YG, UK

¹ Correspondence address. Tel: +44 1223 353329; Fax: +44 1223 358845; E-mail: hoorens{at}rand.org

	Abstract

Top Abstract Introduction Materials and Method Results Discussion Supplementary Data Acknowledgements References

 
Governments worldwide are searching for ways to cope with ageing populations as the demographic shift towards fewer and later births takes hold. The potential contribution of assisted reproductive technologies (ART) to increasing fertility rates has not yet been explored. This paper describes a preliminary study into the impact ART policies might have on population ageing. A deterministic model is developed to quantify the effects of ART policies on total fertility rate (TFR), and tested using data from the UK and Denmark. The population structure for 2050 is modelled to translate fertility rates into time-dependent population dynamics, and the costs of potential ART policies are investigated. If access to ART in the UK were increased to the level of Denmark, the TFR would increase by 0.04, from 1.64 to 1.68. The cumulative effect on the population structure would be a 1.7% decrease in old-age dependency ratio in 2050. Although the empirical models do not include behavioural components, the results demonstrate that ART does have potential to contribute to TFR and influence population structure, and that the direct costs associated with adopting ART as a population policy are comparable with those of existing policies commonly used by governments to influence fertility.

Key words: ART/infertility/demographic ageing/total fertility rate/population policy

	Introduction

Top Abstract Introduction Materials and Method Results Discussion Supplementary Data Acknowledgements References

 
The total fertility rate (TFR) in every nation in the European Union is now below replacement level, usually taken as 2.1 children per woman (Eurostat, 2006). Italy (TFR 1.26), Greece (1.27) and Spain (1.27) have the lowest TFRs in Europe. Between 1992 and 2004, a number of countries, including Austria, Germany, Greece, Italy and Slovenia, experienced a TFR continuously below 1.5 children per woman.

The consequences associated with declining birthrates are manifold. Changes in fertility rate have a significant influence on population age structures. By 2050, one in three Europeans will be over 65 years old, up from one in six in 2000 (Grant and Hoorens, 2006). As the proportion of the working-age population declines relative to the non-working population, the economic and social effects of the demographic shift begin to affect the economic wellbeing of the country. Contributions from the working population to health, pension and welfare funding will decline just as the need is increasing. Fewer younger people mean not only lower tax income, but also fewer people available to provide the care and other services that older people need. Countries with an ageing population may also see a decline in their relative economic importance, which could alter their political standing on the world stage.

As a result, governments are implementing population policies, implicitly or explicitly, aimed at offsetting the consequences of further population ageing. Some of these are as exotic as the Japanese government paying for speed dating parties (Bartlett, 2006). Various other policies are in place across Europe (Grant et al., 2004; Dixon and Margo, 2006; Grant and Hoorens, 2006); the three main options being immigration, reform of the welfare state and raising fertility rates.

Increasing immigration will not provide a long-term solution, not least because the sheer numbers of immigrants needed to compensate for population ageing would be politically debatable. The immigrants themselves would eventually reach retirement age and become part of the problem rather than part of the solution. Welfare state reform, such as raising the retirement age, is high on the agenda for many governments. However, it will only go a part of the way towards solving the financial dilemma of an ageing population, because it only alleviates the negative consequences of ageing and does not affect its causes. Increasing fertility rates by encouraging child-bearing is the aim of a number of European governments that have introduced policies to make it easier to have and raise children. Countries which have implemented such policies tend to have higher fertility rates than those that do not, nonetheless, even these countries have TFRs below replacement level.

One possible option for governments hoping to halt declining fertility rates is to widen the availability of assisted reproductive technologies (ARTs), such as in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), to subfertile couples. To date, the potential impact on fertility rates of helping subfertile couples has not been assessed, perhaps due to its immense complexity and sensitivity. This study starts the process by developing a model to examine the contribution of ART to TFR and population structure over time. The model is tested using empirical data from the UK and Denmark and used to explore a number of fertility scenarios.

	Materials and Method

Top Abstract Introduction Materials and Method Results Discussion Supplementary Data Acknowledgements References

 
The UK and Denmark were chosen for this exploratory study because their population structure is similar, as well as several other demographic indicators (Table 1). At 1.64, the TFR of the UK in 2002 was slightly lower than that of Denmark at 1.72 (Eurostat, 2006). Other demographic indicators are comparable, such as relatively high mean age of women at childbirth (28.7 years and 29.9 years, respectively), arguably one of the main drivers of low fertility, and the differences in life expectancy between the two countries is relatively small. In 2002, a total of 38 083 ART cycles were carried out on women in the UK (equivalent to 625 cycles per million women) and ART births accounted for 1.4% of all live births (Nyboe Andersen et al., 2006). In Denmark, 11 081 ART cycles were carried out in 2002, equivalent to 2106 cycles per million women, and ART births accounted for 4.2% of all live births in the same year (Nyboe Andersen et al., 2006).

View this table: [in this window] [in a new window]   Table 1: Summary of key indicators

 
A deterministic fertility model was developed to quantify the potential impact of ART on TFR. A number of assumptions were made for simplicity and with the acknowledgement that future work should address these assumptions, including that the model considers infertility as a function of female age only; this assumption and others are considered in the ‘Discussion’ section. The full derivation of the model is available from the corresponding author on request, but some aspects are detailed below.

The fertility component of the framework describes the relationship between fertility rates and ART, and assisted and unassisted age-specific fertility rates were derived, given by:

(1)

where ASFR is the age-specific fertility rate, ASFR_F the age-specific fertility rate for fertile women, ASFR_SF that for subfertile women, f is the fraction of fertile women and sf the fraction of subfertile women. This equation assumes that if a couple undergoes ART, the probability of conceiving naturally is zero. The model is described in detail (Supplementary data). When f, ASFR_F and sf are determined empirically, the observed age-specific fertility rate can be reproduced using Equation (1), thus validating the model. Equation (1) was also used to generate a maximum fertility rate, which assumes that all subfertile women achieve the fertility rate of fertile women.

As a first approximation, ASFR_F was taken as a constant. In future, numerical estimations can be obtained from datasets with projections in different future scenarios, as published periodically by Eurostat for instance. Given that ASFR_SF can be varied by the use of ART, changes in TFR for the subfertile population under different ART scenarios were explored. Age-specific fertility rates were derived for the UK and Denmark, and using these and TFRs for both countries, the number of ART cycles were related to the number of births. There were intrinsic problems with the data due to differences of definition and measurement, e.g. sub-fecundity is defined differently by different sources, and relevant data is rare for ages beyond 40 years. For this study, the fraction of subfertile women by age band was taken as an average of values provided by Van Balen (1997), Bongaarts (1982) and Dunson et al. (2004).

Population structures were modelled in order to translate fertility rates into time-dependent population dynamics. The population structure model incorporated population growth rate, population age structure, number of births, probability of survival and age dependency ratios. A number of considerations were made while developing the model, as it was intended to be simple to manipulate and the data requirements reduced to a minimum, but the model can be readily adapted and extended if greater accuracy is required. The effects that different fertility scenarios may have on future population age structures were modelled and used to explore the socio-economic impacts of different ART-affected fertility rates. The old-age dependency ratio, the old-age population (aged 65 and above) as a fraction of the working-age population (aged between 16 and 64), was calculated as an indicator of the extent of population ageing.

Using the results from the fertility model, a cost-benefit analysis of potential ART policies was carried out, using £2771 as the cost of one IVF cycle in the UK (National Collaborating Centre for Women's and Children's Health, 2003). The cost of an ART birth increases as the mother's age increases, due to the lower success rate for older women, particularly women over the age of 40 years. Three cost-benefit scenarios were modelled, where ART was provided to all women, provided only to women below the age of 45 and provided only to women below the age of 40.

	Results

Top Abstract Introduction Materials and Method Results Discussion Supplementary Data Acknowledgements References

 
Total fertility rates
Calculating ASFR and TFR for the UK and Denmark under three scenarios of assisted reproduction uptake indicates that, since the success rates in the UK and Denmark are similar, if access to ART in the UK were increased from the current 625 cycles per million women to the 2106 cycles per million women in Denmark, the TFR would increase by 0.04, from 1.64 to 1.68. The results for the ASFR are shown in Fig. 1 and the TFR results are summarized in Table 2. Conversely, if Denmark ceased to use ART, then the TFR in that country would decrease by 0.07, from 1.72 to 1.65. The maximum impact of ART—the difference between unassisted TFR and maximum TFR—would be 0.22 in the UK and 0.24 in Denmark, which provides an upper-bound estimate for the fertility impact of ART.

View larger version (16K): [in this window] [in a new window] [Download PowerPoint slide]   Figure 1: The empirical and potential impact of ART on ASFR

 

View this table: [in this window] [in a new window]   Table 2: Results for TFRs

 
Population structures
Figure 2 illustrates the consequences of an increase in the number of ART births for the population structure. As the additional men and women born through ART begin to enter the labour force (population between ages 15 and 65), they will contribute to reducing the ratio of old-age dependents to the working population. If access to ART in the UK were increased from the current 625 cycles per million women to the 2106 cycles per million women in Denmark, the cumulative effect on the old-age dependency ratio in 2050 would be a 1.7% decrease.

View larger version (21K): [in this window] [in a new window] [Download PowerPoint slide]   Figure 2: The projected impact of ART on age-structure in the UK, 2050

 
Cost-benefit analysis
As shown in Table 3, when the UK TFR was allowed to increase up to the Danish level and ART was provided to women of all ages, TFR increased by 0.0423, and the estimated cost was £429M. This estimation is based on the ART success rates for the UK published in the NICE Fertility guideline (National Collaborating Centre for Women's and Children's Health, 2003). When women aged 45 and above were excluded, the total cost went down to £387M and the increase in TFR went down to 0.0419. When ART is only provided to women below 40 years of age, the increase in TFR is 0.0364 and the total costs are £259M. The cost per birth was found to be £55K and £277K for women aged 40–44 and 45–49, respectively. In comparison, the average costs per successful IVF birth for women younger than 30 are £13K (ibid).

View this table: [in this window] [in a new window]   Table 3: Cost-benefit analysis of ART provision for women in different age groups

 

	Discussion

Top Abstract Introduction Materials and Method Results Discussion Supplementary Data Acknowledgements References

 
As noted in the introduction, this is a preliminary study that sets out to test the hypothesis of whether ART should be considered alongside existing population policies aimed at increasing fertility rates in Europe (and elsewhere), and thereby offsetting population ageing in these societies. The results demonstrate that ART does have potential to contribute to TFR in the UK. If ART utilization rates in the UK were similar to 2002 utilization rates in Denmark, the TFR would have increased by 0.04. Taking into consideration the existing TFR contribution of ART born children of 0.02, the absolute TFR contribution would have been 0.06.

Gauthier and Hatzius modelled the relationship between policies and fertility for 22 OECD countries between 1970 and 1990 and concluded that a 25% increase in child benefits expenditure would increase TFR by 0.07 in the long term (Gauthier and Hatzius, 1997). Therefore, the 0.04 additional contribution of ART to TFR would be in the same order of magnitude as that of other policies normally considered in the population ageing debate.

The costs of increased utilization of ART, however, are likely to be lower than those of other population policies. In the UK, a 25% increase in child benefit would correspond to between £1.5 and £2.5 billion per annum, or £50k and £100k per additional birth. We estimate the costs associated with the TFR increase due to ART births to be between £250 and £430 x 10⁶ per annum, based on an average cost per IVF cycle of £2771. These costs depend on the criteria for inclusion of different age groups, due to varying success rates with age. Across ages, the success rates of IVF used in the model vary from 21% for women below 30 to 1% for women between 45 and 49. Depending on different inclusion criteria for women's ages (all women, only those younger than 45 or only those younger than 40), the costs per ART birth range between £15K and £25K.

We made a number of assumptions, which need to be addressed in future work. We have assumed that children born through assisted reproduction procedure would not have been conceived naturally, whereas the probability of spontaneous pregnancy for subfertile couples is not negligible; particularly not for women younger than 35. Evers et al. (1998), for example, report that the 12 months cumulative pregnancy rate for patients on the waiting list was between 2.4% and 6.6% depending on the infertility diagnosis. Also, the age distribution of women undergoing ART is assumed to remain constant, whereas in reality, it depends on various aspects related to human reproductive and socio-economic behaviour.

We have also assumed that a couple's ability to conceive is largely dependent on the woman's age and we have not accounted for male infertility. And, despite the health effects associated with the higher probability of multiple births due to multiple embryo transfers (e.g. De Sutter et al., 2002; Schieve et al., 2004), we have assumed that ART babies are identical (biologically and from a socio-economic point of view) to non-ART babies.

In the population dynamics model, fertility and mortality are assumed to be constant over time based on 2002 data. To simplify the model, the influence of migration on population dynamics has been omitted.

Although ART includes multiple techniques, we have only included data on births through IVF and ICSI, as these methods constitute the majority of births through ART. In some settings, artificial insemination using husband's (AIH) or donor (AID) semen is also considered ART and from several countries a large number of such treatment cycles are reported (Nyboe Andersen et al., 2006). Additionally, new technologies may be developed to deal with infertility and subfertility over the coming years, but within the scope of this study, we have assumed that this will not be the case.

The quality of the data underlying the models could be improved in a number of ways. In particular, the data on the age-specific proportion of subfertile couples varies across different sources, and there seem to be no universally accepted figures. This is due to inconsistent definitions and measurement difficulties.

The assumption that only the age-specific fertility rates of subfertile couples are affected by the availability of ART may be inaccurate. In particular, the results of this study have assumed that increased availability of ART services does not impact on birth timing (i.e. age at giving birth). In reality, this relationship would need to be tested to ensure that improved access to ART services does not unintentionally influence couples to delay childbearing with the presumption that they can rely on ART treatment if required in the future (Gillan, 2006). If such a temporal effect were to occur, this could impact natural fecundity rates and potentially increase demand for ART services among older women, where treatment success rates are known to diminish.

While such a temporal effect could result from future policy changes, available data suggest this may not be the case. In Denmark, where ART receives generous public funding compared with funding in the UK, the average age of women treated with ART in Denmark is lower than the average age of those treated in the UK (Fig. 3). These figures may suggest the contrary in that the availability of ART encourages couples to seek help sooner rather than later. However, on average, the age of mothers at the birth of their first child is overall lower in Denmark (27.5 years) than in the UK (29.1 years). This could also explain the age-profile difference between women undergoing ART treatment in the two countries. Future work is needed to establish the relationship between publicly available ART and utilization decisions.

View larger version (39K): [in this window] [in a new window] [Download PowerPoint slide]   Figure 3: Percentage of women treated with IVF by age band, 2002 (Nyboe Andersen et al., 2006)

 
The empirical models do not include behavioural components. For this reason, the potential effects related to the timing of childbirth are presently unresolved. Behaviour relates not only to marriage, sexual activity and contraceptive use, but also the willingness to pay for IVF cycles, government policies that influence individual behaviour and external factors. An initial theoretical behavioural model has been developed to begin to address this issue, and represents a solid base for further research.

	Supplementary Data

Top Abstract Introduction Materials and Method Results Discussion Supplementary Data Acknowledgements References

 
Supplementary data are available at http://humrep.oxfordjournals.org/.

	Acknowledgements

Top Abstract Introduction Materials and Method Results Discussion Supplementary Data Acknowledgements References

 
The authors wish to acknowledge Ferring Pharmaceuticals, who provided the unrestricted grant enabling this research. We would also like to thank the following persons for their critical comments: the peer reviewers, Professor William L. Ledger (University of Sheffield), Julius Op De Beke (European Commission DG Employment and Social Affairs), Dr Julie DaVanzo and Dr Eric Petersen (RAND). We would also like to thank Kate Kirk and Lynne Saylor for their support.

	Footnotes

 
^* All authors work for RAND Europe, an independent, not-for-profit, research institution that helps improve policy and decision-making through objective research and analysis. RAND Europe, based in Cambridge, UK, is part of the globally operating think tank RAND Corporation. The authors have experience and expertise in policy analysis, population studies, health policy and economics.

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Submitted on January 10, 2007; resubmitted on May 2, 2007; accepted on May 24, 2007.

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This Article Abstract FREE Full Text (PDF ) Supplementary Data All Versions of this Article: 22/9/2471    most recent dem181v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Add to My Personal Archive Download to citation manager Search for citing articles in: ISI Web of Science (13) Request Permissions Google Scholar Articles by Hoorens, S. Articles by Grant, J.C. Search for Related Content PubMed PubMed Citation Articles by Hoorens, S. Articles by Grant, J.C. Social Bookmarking          What's this?

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