Estimates of lifetime infertility from three states: the behavioral risk factor surveillance system

Infertility prevalence and the methods of estimation from 1990 to 2021: a systematic review and meta-analysis

STUDY QUESTION

What is the contemporary prevalence of infertility in world populations and how do they differ by methodological and study characteristics?

SUMMARY ANSWER

Pooled estimates of lifetime and period prevalence of 12-month infertility were 17.5% and 12.6%, respectively, but this varied by study population and methodological approach.

WHAT IS KNOWN ALREADY

Infertility affects millions of individuals worldwide. Accurate measures of its magnitude are needed to effectively address and manage the condition. There are distinct challenges and variation in how infertility is defined and measured, limiting comparability of estimates across studies. Further research is needed to understand whether and how differences in methodological approaches and study characteristics account for heterogeneity in estimates.

STUDY DESIGN SIZE DURATION

We conducted a systematic review and meta-analysis. Six electronic databases, websites of relevant organizations, and conference proceedings were systematically searched. Searches were limited to those published between 1 January 1990 and 11 March 2021, with no language restrictions.

PARTICIPANTS/MATERIALS SETTING METHODS

Descriptive and random-effects meta-analysis models were used to examine range of estimates and generate estimates of pooled lifetime and period prevalence of 12-month infertility, respectively, among representative populations. Meta-regression using restricted maximum likelihood was applied to account for definitional and study characteristics and to obtain adjusted estimates. Risk of bias was assessed with a validated tool.

MAIN RESULTS AND THE ROLE OF CHANCE

The search yielded 12 241 unique records of which 133 studies met the criteria for the systematic review. There were 65 and 69 studies that provided data for lifetime and period prevalence of 12-month infertility, respectively. Five methodological approaches were identified: prospective time-to-pregnancy (TTP) design, current duration design, retrospective TTP design, self-reported infertility measure and constructed infertility measure. Ranges for lifetime (3.3-39.7%) and period estimates (1.6-34.0%) were similar and wide even after accounting for methodological and study characteristics. Pooled estimates of lifetime and period prevalence were 17.5% (95% CI: 15.0, 20.3, n = 37 studies, I ² = 99.5%) and 12.6% (95% CI: 10.7, 14.6, n = 43 studies, I ² = 99.8%), respectively, with some variation in magnitude by region and methodological approach, but with most CIs overlapping.

LIMITATIONS REASONS FOR CAUTION

Pooled estimates generated from meta-analysis were derived from 12-month infertility prevalence estimates that were heterogeneous across different domains, even after adjusting for definitional and study characteristics. The number of studies was small for certain strata from which pooled estimates were derived (e.g. there were only two studies for lifetime prevalence in Africa).

WIDER IMPLICATIONS OF THE FINDINGS

While findings show a high prevalence of infertility globally and regionally, it also reveals variation in measures to ascertain and compare infertility prevalence. More systematic and comprehensive collection of data using a consistent definition is needed to improve infertility prevalence estimates at global, regional and country-levels.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the World Health Organization. The authors have no conflicts of interest.

REGISTRATION NUMBER

PROSPERO CRD42020211704.

International Natural Procreative Technology Evaluation and Surveillance of Treatment for Subfertility (iNEST): enrollment and methods

STUDY QUESTION

What is the feasibility of a prospective protocol to follow subfertile couples being treated with natural procreative technology for up to 3 years at multiple clinical sites?

SUMMARY ANSWER

Overall, clinical sites had missing data for about one-third of participants, the proportion of participants responding to follow-up questionnaires during time periods when participant compensation was available (about two-thirds) was double that of time periods when participant compensation was not available (about one-third) and follow-up information was most complete for pregnancies and births (obtained from both clinics and participants).

WHAT IS KNOWN ALREADY

Several retrospective single-clinic studies from Canada, Ireland and the USA, with subfertile couples receiving restorative reproductive medicine, mostly natural procreative technology, have reported adjusted cumulative live birth rates ranging from 29% to 66%, for treatment for up to 2 years, with a mean women’s age of about 35 years.

STUDY DESIGN, SIZE, DURATION

The international Natural Procreative Technology Evaluation and Surveillance of Treatment for Subfertility (iNEST) was designed as a multicenter, prospective cohort study, to enroll subfertile couples seeking treatment for live birth, assess baseline characteristics and follow them up for up to 3 years to report diagnoses, treatments and outcomes of pregnancy and live birth. In addition to obtaining data from medical record abstraction, we sent follow-up questionnaires to participants (both women and men) to obtain information about treatments and pregnancy outcomes, including whether they obtained treatment elsewhere. The study was conducted from 2006 to 2016, with a total of 10 clinics participating for at least some of the study period across four countries (Canada, Poland, UK and USA).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The 834 participants were subfertile couples with the woman’s age 18 years or more, not pregnant and seeking a live birth, with at least one clinic visit. Couples with known absolute infertility were excluded (i.e. bilateral tubal blockage, azoospermia). Most women were trained to use a standardized protocol for daily vulvar observation, description and recording of cervical mucus and vaginal bleeding (the Creighton Model FertilityCare System). Couples received medical and sometimes surgical evaluation and treatments aimed to restore and optimize female and male reproductive function, to facilitate in vivo conception.

MAIN RESULTS AND THE ROLE OF CHANCE

The mean age of women starting treatment was 34.0 years; among those with additional demographic data, 382/478 (80%) had 16 or more years of education, and 199/659 (30%) had a prior live birth. Across 10 clinical sites in four countries (mostly private clinical practices) with family physicians or obstetrician–gynecologists, data about clinic visits were submitted for 60% of participants, and diagnostic data for 77%. For data obtained directly from the couple, 59% of couples had at least one follow-up questionnaire, and the proportion of women and men responding to fill out the follow-up questionnaires was 69% and 67%, respectively, when participant financial compensation was available, compared to 38% and 33% when compensation was not available. Among all couples, 57% had at least one pregnancy and 44% at least one live birth during the follow-up time period, based on data obtained from clinic and/or participant questionnaires. All sites reported on female pelvic surgical procedures, and among all participants, 22% of females underwent a pelvic diagnostic and/or therapeutic procedure, predominantly laparoscopy and hysterosalpingography. Among the 643 (77%) of participants with diagnostic information, ovulation-related disorders were diagnosed in 87%, endometriosis in 31%, nutritional disorders in 47% and abnormalities of semen analysis in 24%. The mean number of diagnoses per couple was 4.7.

LIMITATIONS, REASONS FOR CAUTION

The level of missing data was higher than anticipated, which limits both generalizability and the ability to study different components of treatment and prognosis. Loss to follow-up may also be differential and introduce bias for outcomes. Most of the participating clinicians were not surgeons, which limits the opportunity to study the impact of surgical interventions. Participants were geographically dispersed but relatively homogeneous with regard to socioeconomic status, which may limit the generalizability of current and future findings.

WIDER IMPLICATIONS OF THE FINDINGS

Multicenter studies are key to understanding the outcomes of subfertility treatments beyond IVF or IUI in broader populations, and the association of different prognostic factors with outcomes. We anticipate that the iNEST study will provide insight for clinical and treatment factors associated with outcomes of pregnancy and live birth, with appropriate attention to potential biases (including adjustment for potential confounders, multiple imputation for missing data, sensitivity analysis and inverse probability weighting for potential differential loss to follow-up, and assessments for clinical site heterogeneity). Future studies will need to either have: adequate funding to compensate clinics and participants for robust data collection, including targeted randomized trials; or a scaled-down, registry-based approach with targeted data points, similar to the multiple national and regional ART registries.

STUDY FUNDING/COMPETING INTEREST(S)

Funding for the study came from the International Institute for Restorative Reproductive Medicine, the University of Utah, Department of Family and Preventive Medicine, Health Studies Fund, the Primary Children’s Medical Foundation, the Mary Cross Tippmann Foundation, the Atlas Foundation, the St. Augustine Foundation and the Women’s Reproductive Health Foundation. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

The iNEST study is registered at clinicaltrials.gov, NCT01363596.

Fertility and Birth Outcomes in Women With Epilepsy Seeking Pregnancy

Importance

Prior studies report lower birth rates for women with epilepsy (WWE) but have been unable to differentiate between biological and social contributions. To our knowledge, we do not have data to inform WWE seeking pregnancy if their likelihood of achieving pregnancy is biologically reduced compared with their peers.

Objective

To determine if WWE without a prior diagnosis of infertility or related disorders are as likely to achieve pregnancy within 12 months as their peers without epilepsy.

Design, Setting, and Participants

The Women With Epilepsy: Pregnancy Outcomes and Deliveries study is an observational cohort study comparing fertility in WWE with fertility in control women (CW) without epilepsy. Participants were enrolled at 4 academic medical centers and observed up to 21 months from November 2010 to May 2015. Women seeking pregnancy aged 18 to 40 years were enrolled within 6 months of discontinuing contraception. Exclusion criteria included tobacco use and a prior diagnosis of infertility or disorders that lower fertility. Eighteen WWE and 47 CW declined the study, and 40 WWE and 170 CW did not meet study criteria. The Women With Epilepsy: Pregnancy Outcomes and Deliveries electronic diary app was used to capture data on medications, seizures, sexual activity, and menses. Data were analyzed from November 2015 to June 2017.

Main Outcomes and Measures

The primary outcome was proportion of women who achieved pregnancy within 12 months after enrollment. Secondary outcomes were time to pregnancy using a proportional hazard model, pregnancy outcomes, sexual activity, ovulatory rates, and analysis of epilepsy factors in WWE. All outcomes were planned prior to data collection except for time to pregnancy.

Results

Of the 197 women included in the study, 142 (72.1%) were white, and the mean (SD) age was 31.9 (3.5) years among the 89 WWE and 31.1 (4.2) among the 108 CW. Among 89 WWE, 54 (60.7%) achieved pregnancy vs 65 (60.2%) among 108 CW. Median time to pregnancy was no different between the groups after controlling for key covariates (WWE: median, 6.0 months; 95% CI, 3.8-10.1; CW: median, 9.0 months; 95% CI, 6.5-11.2; P = .30). Sexual activity and ovulatory rates were similar in WWE and CW. Forty-four of 54 pregnancies (81.5%) in WWE and 53 of 65 pregnancies (81.5%) in CW resulted in live births. No epilepsy factors were significant.

Conclusions and Relevance

Women with epilepsy seeking pregnancy without prior known infertility or related disorders have similar likelihood of achieving pregnancy, time to pregnancy, and live birth rates compared with their peers without epilepsy.

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

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.

Risks Factors and Treatment Use Related to Infertility and Impaired Fecundity Among Reproductive-Aged Women

INTRODUCTION

Population-level data on infertility and impaired fecundity are sparse. We explored the use of self-reported information provided by reproductive-aged women participating in the Centers for Disease Control and Prevention's Behavioral Risk Factor Surveillance System (BRFSS).

MATERIALS AND METHODS

Three out of 12 questions on reproductive history, family planning, and infertility that seven states included in the 2013 BRFSS were used for this study. In addition to descriptive statistics, we used multinomial logistic regression to identify factors associated with ever experiencing infertility only, difficulty staying pregnant only, and neither infertility nor difficulty staying pregnant. We also explored the association between healthcare coverage and type of treatment received among women ever experiencing infertility only or difficulty staying pregnant only.

RESULTS

Compared with women reporting having never experienced either infertility or difficulty staying pregnant, women who reported ever experiencing difficulty staying pregnant only were significantly more likely to report a history of depressive disorders and smoking (adjusted odds ratio [aOR] = 1.69, 95% confidence interval [CI] = 1.07-2.68 and aOR = 1.98, 95% CI = 1.22-3.20, respectively). Women who ever experienced infertility only were also more likely to report a history of depressive disorders (aOR = 2.02, 95% CI = 1.14-3.59), but less likely to report healthcare coverage (aOR = 0.26, 95% CI = 0.14-0.46). Only 18.9% (95% CI = 11.4-29.9) of women who ever experienced difficulty staying pregnant only reported seeking infertility treatment compared with 49.6% (95% CI = 34.9-64.4) of women who ever experienced infertility only.

CONCLUSIONS

Ongoing public health surveillance systems of state-specific self-reported data, such as BRFSS, provide the opportunity to explore preventable risk factors and treatment use related to infertility and impaired fecundity.

Behavioral Risk Factor Surveillance System State-Added Questions: Leveraging an Existing Surveillance System to Improve Knowledge of Women's Reproductive Health

As the prevalence of chronic conditions among women of reproductive age continues to rise, studies assessing the intersection of chronic disease and women's reproductive health status are increasingly needed. However, many data systems collect only limited information on women's reproductive health, thereby hampering the appraisal of risk and protective factors across the life span. One way to expand the study of women's health with minimal investment in time and resources is to integrate questions on reproductive health into existing surveillance systems. In 2013, previously validated questions on women's self-reported reproductive history, use of contraception, and infertility were added to the Behavioral Risk Factor Surveillance System (BRFSS) by seven states (Connecticut, Kentucky, Massachusetts, Mississippi, Ohio, Texas, and Utah); all female respondents aged 18-50 years were included in the pool of respondents for these state-added questions. Of 8691 women who completed the questions, 13.2% reported ever experiencing infertility and 59.8% of those at risk for unintended pregnancy reported using contraception at last intercourse. The information garnered from the state-added reproductive health questions can be augmented with the BRFSS core questions on health-related risk behaviors, chronic conditions, and use of preventive services. Expanding existing data collection systems with supplemental questions on women's reproductive health can provide important information on risk factors and outcomes that may not be available from other sources.