Prevalence of infertility and help seeking among 15 000 women and men

1Fertility is a key element of reproductive health and infertility is recognized as a global public health issue by the World Health Organisation (WHO). Infertility is defined by the International Committee for Monitoring Assisted Reproductive Technology (ICMART) and WHO as the ‘failure to achieve a pregnancy after 12 months or more of regular unprotected sexual intercourse’. The National Institute for Health and Care Excellence (NICE) guideline for England and Wales concurs with this time period, advocating that clinical assessment and investigation should be offered when ‘a woman of reproductive age… has not conceived after one year of unprotected vaginal sexual intercourse, in the absence of any known cause of infertility’. The experience of infertility can cause those affected personal distress, significant treatment costs and, in some contexts, ostracism and discrimination.

2Infertility is experienced by an estimated 48.5 million couples worldwide and around 1 in 7 couples in the UK. However, prevalence estimates of lifetime infertility vary widely, in part because there is no agreed or consistent definition of infertility and because study populations vary by age range, unit of measurement and relationship status.

3A marked trend for delaying the timing of first birth has been seen in developed and, more recently, developing countries. A consequence of postponement of parenthood is the potential for impaired fertility and the risk that deferral of parenthood will rule it out.

4Later parenthood, its implications for fertility, and the increased range and availability of fertility treatments are likely to have had an impact on help seeking. There is some evidence of an increase in the reporting of fertility problems to primary care after the introduction of national treatment guidelines, suggesting more awareness of assisted reproductive technology (ART). Studies have found that women in later age cohorts are more likely to seek help than women in earlier ones and that women are seeking help at older ages than was previously the case. There are few population-based data on experience of infertility and its determinants or on the extent of help seeking, particularly for men. This study uses data from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) to estimate the prevalence of infertility, and of seeking medical or professional help among women and men in Britain, and to examine associated factors.

5Natsal-3 is a survey of 15 162 women (8869) and men (6293) aged 16–74 years. Households were selected using stratified probability sampling from which one eligible individual resident in Britain was selected at random and invited to participate. The sample frame was the Postcode Address File (PAF), a regularly updated list of all addresses in the country. As the PAF excludes those who are homeless or living in institutions, our sample is representative of individuals living in private residential households. Data were weighted in two stages to correct for participants' unequal probabilities of selection. The first corrected for the selection of one household in multi-household addresses and for the varying probabilities of selection by number of adults within households. The second adjusted for differential non-response by comparing age, sex and region profile of participants with 2011 census data. Although the Natsal-3 sample closely matched those who responded to the census in terms of ethnicity (86.8% in Natsal-3 and 86.7% in the census were white), there was a slight under-representation of Asian women and men in Natsal-3 (6.4%) compared with the census (7.5%). Participants were interviewed between 2010 and 2012 using computer-assisted personal interviewing (CAPI), which included a computer-assisted self-interview (CASI) component for the more sensitive questions. The response rate was 57.7% and the co-operation rate (i.e. of all eligible addresses contacted) was 65.8%. Further details of the methods are described elsewhere.

6Questions about experience of infertility and help seeking for infertility were asked of all Natsal-3 participants who reported ever having heterosexual intercourse (8315 women and 5742 men). Two discrete questions were asked: ‘Have you ever had a time, lasting 12 months or longer, when you and a partner were trying for a pregnancy but it didn't happen?’ and ‘Have you (or a partner) ever sought medical or professional help about infertility?’. In line with the NICE guideline, we considered a participant to have experienced infertility when she or he responded ‘yes’ to the first question. Participants were also asked questions that comprise the validated Patient Health Questionnaire-2 (PHQ-2), a composite measure of depression experienced in the 2 weeks prior to interview and questions on satisfaction with sex life and relationship in the past year.

7Data are cross-sectional and we did not ask participants for information about when their experience of infertility occurred. Some may have failed to conceive in a 12-month period before becoming parents or between pregnancies while others may never have become parents. Those still of reproductive age could experience a future period of infertility. Natsal-3 data are deposited at the UK Data Service. https://discover.ukdataservice.ac.uk/catalogue/?sn=7799 (11 May 2016, date last accessed).

8We used STATA v13.1 to undertake complex survey analyses to account for the weighting, clustering and stratification of the Natsal-3 data. We estimated the population prevalence of infertility and help seeking, stratified by gender and age group. We used multivariable logistic regression to explore associations (adjusted for age at interview) between experience of (i) infertility and (ii) help seeking, and a number of socio-demographic, relationship, reproductive and health factors, including: age at interview; relationship status at interview; age at first cohabitation; age at first child; academic attainment; employment status measured using National Statistics Socio-Economic Classification (NS-SEC) and area-level deprivation measured using the Index of Multiple Deprivation (IMD). We report results for educational attainment for those aged over 21 years only as younger participants may not have completed full-time education. Finally, using multivariable logistic regression, we present age-adjusted odds ratios to describe associations between experience of infertility and selected health and relationship ‘outcome’ variables for women aged 50 years or younger. We selected this age group for analysis as their experience of infertility will have occurred more recently than that of older participants.

9The Natsal-3 study was approved by the Oxfordshire Research Ethics Committee A (ref.: 10/H0604/27).

10The proportion of participants aged 16–74 who reported ever having tried unsuccessfully for a year or longer to become pregnant was 12.5% among women and 10.1% among men (Table I). Unsurprisingly, the prevalence of ever experience of infertility was lowest in the youngest women and peaked among those aged 35–44 years (17.7%). A similar pattern was seen for men but the age range in which the prevalence of ever experience of infertility was highest was wider than for women, extending from age 35 to 54 years at interview.

11The experience of infertility was associated with relationship factors. It was highest among those who were married or cohabiting at interview and lowest among those in a non-cohabiting partnership. Among women, a positive association was found between older age at first cohabitation and the experience of infertility. Age-adjusted odds of experiencing infertility were significantly higher among women who first gave birth at age 35 or older (AOR 5.57 (3.97–7.83)) compared with those who did so before age 25. A similar, though slightly weaker, association was observed among men (AOR 3.27 (2.16–4.96)).

12We found evidence of associations between infertility and indicators of socio-economic status. Experience of infertility was most common among women with a degree and lowest among those with no academic qualifications while no statistically significant association was observed among men. Prevalence was also higher among those in managerial, professional and technical employment compared with those in routine occupations. No association was found between infertility and area-related deprivation at interview among women or men.

13Among women, the only health indicator found to be meaningfully associated with infertility was treatment for depression in the previous 12 months and the association was of only borderline significance (Supplementary data, Table SI). Among men, we found associations with ever having been diagnosed with a sexually transmitted infection (men: AOR 1.39 (1.02–1.88)) and, specifically, with chlamydia (AOR 1.81 (1.15–2.84)).

14A total of 57.3% of women and 53.2% of men who had ever experience of infertility had sought medical or professional help as a result (Table II). Figure 1 shows the proportion of women and men with experience of infertility who sought help for the problem by age group at interview.

15Less than one-third (32.6%) of the youngest women (16–24 years) and only 14.1% of the youngest men with experience of infertility reported seeking help. Among both women and men, similar proportions of those aged 35–74 had sought help (women: 58.0–64.9%; men: 53.1–58.1%).

16Age-adjusted odds ratios showed help seeking to be higher among those who were currently married or cohabiting compared with those in non-cohabiting or not in ‘steady’ partnerships. Prevalence of seeking help was highest in women who first cohabited in their twenties while, among men, it was highest in those who first cohabited aged 30 or older.

17For women, having had a child and older age at first birth were both associated with seeking help for fertility; help seeking was highest among women who became mothers at 35 or older (74.6% (62.8–83.7)). The association between age at first child and help seeking was less marked among men. Of those who had never had a child, 58.7% (95% CI 51.5–65.4) of women and 54.9% (95% CI 46.6–62.9) of men reported having sought help.

18Help seeking was significantly associated with indicators of socio-economic position. Women and men with lower levels of education and lower occupational classifications (as indicated by the NS-SEC) were less likely to have sought help. Associations between help seeking and area-level deprivation at interview were of borderline significance among women only.

19Health indicators were not associated with likelihood of having sought help for infertility although there was a borderline association suggesting that men who reported regular heavy drinking were slightly less likely to have sought help (Supplementary data, Table SII).

20Table III presents the associations between experience of infertility and three variables which we have treated as ‘outcomes’ for the purposes of this analysis. We found a positive and significant association between ever experience of infertility and symptoms of depression in the 2 weeks before interview and dissatisfaction with sex life in the past year among women aged 50 and under. These associations remained after controlling for potential confounding factors including age at interview, educational qualification, relationship status at interview, duration of relationship, age at first cohabitation and parental status. We examined whether having children or not moderated the association between experience of infertility and depression and identified no evidence of an interaction (P = 0.698). Given the limitations of the data, we do not know whether depression or sexual dissatisfaction was related to the use of fertility treatments. We found no significant association between women's experience of infertility and whether they were happy with their current relationship. Among men, no significant association was observed between the experience of infertility and depression, dissatisfaction with sex life, or happiness with relationship (analysis not shown).

21In this study, we provide population prevalence estimates of infertility and help seeking among women and men in Britain using national probability survey data. One in eight women and one in ten men experienced infertility defined by unsuccessfully attempting pregnancy for a year or more. Women and men who settled later with a partner, had higher educational attainment and occupational status and, among those who did have a child, became parents at older ages were more likely to have experienced infertility.

22Little more than half of women and men who had experienced infertility had sought medical or professional help for the problem. Those who did so were better educated and in higher status occupations and, if they were parents, were more likely to have had children at older ages. These characteristics were more marked among women than men. Women aged 50 or younger who had experience of infertility were more likely to report recent symptoms of depression and dissatisfaction with their sex life. We found that ever experience of infertility and of help seeking were associated with few current health factors for women or men.

23A strength of this study is the size of the sample and the fact that it is population-based. Natsal-3 includes data on sexual and reproductive health as well as behavioural and relationship variables less common in health surveys. A limitation is that, although we measure ever experience of infertility, some explanatory variables refer to recent time frames. As data are cross-sectional, it is not possible to establish temporality or infer causality and we cannot establish the age of participants when they experienced infertility or sought help, or the timing of these experiences relative to having children for those who did. Self-reported data may be subject to recall bias. It was not possible to explore associations between infertility and participant ethnicity as numbers were too small.

24Our estimates of infertility are broadly in line with those found by previous studies although prevalence estimates differ as a result of diverse definitions and study populations. Earlier estimates of women experiencing infertility range from around 1 in 5 to around 1 in 10 with the National Women's Health Study reporting about 1 in 6. Estimates of couples' experience of infertility also vary. estimated it to be around one in six while NICE cites estimates of one in seven.

25A large body of literature describes the trend among women in developed countries to delay having children and it is proposed that this changing fertility tempo is becoming a global phenomenon.

26Our finding that infertility was more commonly experienced by married or cohabiting participants probably reflects the fact that those in stable relationships are more likely to have attempted pregnancy and therefore become aware of fertility problems. The much lower prevalence among young people reflects in part that they may never have tried to get pregnant. Previous studies have noted the extended period of transition to adulthood and the widening intervals between the key reproductive events of first sex, first cohabitation and first birth. Researchers taking a life course perspective have observed discrepancies between individuals' fertility intentions and their subsequent family size, highlighting the complex interaction of childhood socialization with personal and structural factors. Influences on postponement for women include the increase in women's participation in further education and in career development, the absence of a ‘suitable’ partner, partner's expectations and perceptions of how parenthood will reduce individual autonomy.

27Our estimate that 57% of women sought medical help for infertility is close to that reported by an international review which estimated that 56% of women in more developed countries sought help, and by a Finnish study which found that 57% of all subfertile women did so. Other studies have reported higher and lower estimates but, because of differences in study groups and outcome measures, comparison is not possible.

28Our analyses show that women aged 50 or under who experienced infertility were more likely to report recent symptoms of depression and dissatisfaction with their sex life. Infertility is associated with psychological distress and patients find the process of undergoing infertility treatment and its uncertain outcome stressful. The longer term impact of infertility on mental health and sexual well-being is less well known. A Danish study shows a relationship between unsuccessful ART and severe depressive symptoms a year after initiating treatment and another, also Danish, found women who did not have a child after fertility treatment were more likely to commit suicide than those who did. Previous research has found associations between undergoing treatment for infertility and sexual dissatisfaction, particularly among women.

29The large minority of research participants who experienced infertility but did not seek medical help is of concern, as are the marked inequalities in help seeking between those who are well qualified and in high status employment and those who are not. These findings are in line with other studies from Europe, North America and Australia. Several explanations for not seeking (or pursuing) help for infertility have been suggested, including not understanding or acknowledging that a problem exists, fear of being labelled infertile, concerns about the cost of treatment, lack of intent to conceive and the physical and psychological burden of treatment. These do not provide a clear rationale for why there should be a distinction between indicators of social status and the likelihood of seeking help, although it has been suggested that acknowledging lack of conception as a problem to be solved is a motivation for seeking treatment and that highly educated women may be better informed about how long conception might typically take.

30Interventions to encourage help seeking include raising public awareness about reproductive risks and strategies to minimise them, general practitioners taking opportunities to discuss fertility with patients, greater access to fertility treatments and an acknowledgement of the psychosocial impacts of infertility, including the long-term effects, by health practitioners and the availability of appropriate support.

31Supplementary data are available at http://humrep.oxfordjournals.org/.

32J.D., K.W., C.T. and M.P. conceived the paper; all authors contributed to data acquisition and interpretation; M.P., L.J.G. and K.G.J. conducted the statistical analysis; J.D. wrote the first draft with contributions from all other authors. All authors approved the final draft.

33The study was funded by grants from the Medical Research Council and the Wellcome Trust with contributions from the Economic and Social Research Council and Department of Health. K.G.J. was supported by a National Institute for Health Research Methods Fellowship. Funding to pay the Open Access publication charges for this article was provided by MRC and Wellcome Trust.

34AMJ is a Governor of the Wellcome Trust. Other authors declare no conflicts of interest.