Estimating infertility prevalence in low-to-middle-income countries: an application of a current duration approach to Demographic and Health Survey data

Abstract

Study question: Can infertility prevalence be estimated using a current duration (CD) approach when applied to nationally representative Demographic and Health Survey (DHS) data collected routinely in low- or middle-income countries?

Summary answer: Our analysis suggests that a CD approach applied to DHS data from Nigeria provides infertility prevalence estimates comparable to other smaller studies in the same region.

What is known already: Despite associations with serious negative health, social and economic outcomes, infertility in developing countries is a marginalized issue in sexual and reproductive health. Obtaining reliable, nationally representative prevalence estimates is critical to address the issue, but methodological and resource challenges have impeded this goal.

Study design, size, duration: This cross-sectional study was based on standard information available in the DHS core questionnaire and data sets, which are collected routinely among participating low-to-middle-income countries. Our research question was examined among women participating in the 2013 Nigeria DHS (n = 38 948). Among women eligible for the study, 98% were interviewed.

Participants/materials, setting, methods: We applied a CD approach (i.e. current length of time-at-risk of pregnancy) to estimate time-to-pregnancy (TTP) and 12-month infertility prevalence among women 'at risk' of pregnancy at the time of interview (n = 7063). Women who were 18-44 years old, married or cohabitating, sexually active within the past 4 weeks and not currently using contraception (and had not been sterilized) were included in the analysis. Estimates were based on parametric survival methods using bootstrap methods (500 bootstrap replicates) to obtain 95% CIs.

Main results and the role of chance: The estimated median TTP among couples at risk of pregnancy was 5.1 months (95% CI: 4.2-6.3). The estimated percentage of infertile couples was 31.1% (95% CI: 27.9-34.7%)-consistent with other smaller studies from Nigeria. Primary infertility (17.4%, 95% CI: 12.9-23.8%) was substantially lower than secondary infertility (34.1%, 95% CI: 30.3-39.3%) in this population. Overall estimates for TTP >24 or >36 months dropped to 17.7% (95% CI: 15.7-20%) and 11.5% (95% CI: 10.2-13%), respectively. Subgroup analyses showed that estimates varied by age, coital frequency and fertility intentions, while being in a polygynous relationship showed minimal impact.

Limitations, reasons for caution: The CD approach may be limited by assumptions on when exposure to risk of pregnancy began and methodologic assumptions required for estimation, which may be less accurate for particular subgroups or populations. Unrecognized pregnancies may have also biased our findings; however, we attempted to address this in our exclusion criteria. Limiting to married/cohabiting couples may have excluded women who are no longer in a relationship after being blamed for infertility. Although probably rare in this setting, we lack information on couples undergoing infertility treatment. Like other TTP measurement approaches, pregnancies resulting from contraceptive failure are not included, which may bias estimates.

Wider implications of the findings: Nationally representative estimates of TTP and infertility based on a clinical definition of 12 months have been limited within developing countries. This approach represents a pragmatic advance in our ability to measure and monitor infertility in the developing world, with potentially far-reaching implications for policies and programs intended to address reproductive health.

Study funding/competing interests: There are no competing interests and no financial support was provided for this study. Financial support for Open Access publication was provided by the World Health Organization.

Keywords: current duration; developing countries; infertility; survival analysis; time-to-pregnancy.

Figure 1

Eligibility criteria for the CD sample. ^†Excluded if: respondents were not between 18 and 44 years of age; were not married or cohabitating; were not sexually active in the last 4 weeks; were currently using contraception (or had been sterilized); were currently pregnant, had given birth in the past 3 months, or were postpartum amenorrheic; had used depot medroxyprogesterone acetate within the last 10 months; were menopausal or had a hysterectomy; had never menstruated; or were missing information related to the timing of first sexual intercourse with current partner or did not have reproductive calendar data, or had calculated CD values <0. ^£Eligible sample was determined from the minimum duration based on the time from most recent family planning use (or, if depot medroxyprogesterone acetate, most recent use of depot medroxyprogesterone acetate −10 months) (count = 167), most recent live birth minus postpartum abstinence or amenorrhea (count = 4225), most recent pregnancy that did not end in a live birth (count = 498), start of relationship with current partner (count = 716) or no events in the past 5 years (count = 1480) to the time at interview. Counts represent the number of times components of the CD values were equivalent to the final CD value, which may sum to over 7063 due to ‘ties’ between each of the components. CD, current duration.

Figure 2

Survival function for TTP or end of pregnancy attempt estimated using a CD approach. Solid line represents the curves for the estimated TTP; dotted lines represent the 95% CIs around those curves, TTP, time-to-pregnancy.