US climate policy yields water quality cobenefits in the Mississippi Basin and Gulf of Mexico.

We utilize a coupled economy-agroecology-hydrology modeling framework to capture the cascading impacts of climate change mitigation policy on agriculture and the resulting water quality cobenefits. We analyze a policy that assigns a range of United States government's social cost of carbon estimates ($51, $76, and $152/ton of CO2-equivalents) to fossil fuel-based CO2 emissions. This policy raises energy costs and, importantly for agriculture, boosts the price of nitrogen fertilizer production. At the highest carbon price, US carbon emissions are reduced by about 50%, and nitrogen fertilizer prices rise by about 90%, leading to an approximate 15% reduction in fertilizer applications for corn production across the Mississippi River Basin. Corn and soybean production declines by about 7%, increasing crop prices by 6%, while nitrate leaching declines by about 10%. Simulated nitrate export to the Gulf of Mexico decreases by 8%, ultimately shrinking the average midsummer area of the Gulf of Mexico hypoxic area by 3% and hypoxic volume by 4%. We also consider the additional benefits of restored wetlands to mitigate nitrogen loading to reduce hypoxia in the Gulf of Mexico and find a targeted wetland restoration scenario approximately doubles the effect of a low to moderate social cost of carbon. Wetland restoration alone exhibited spillover effects that increased nitrate leaching in other parts of the basin which were mitigated with the inclusion of the carbon policy. We conclude that a national climate policy aimed at reducing greenhouse gas emissions in the United States would have important water quality cobenefits.

Incorporating learning into direct policy search for flood risk management.

Direct policy search (DPS) is a method for identifying optimal policies (i.e., rules) for managing a system in response to changing conditions. In this article, we introduce a new adaptive way to incorporate learning into DPS. The standard DPS approach identifies "robust" policies by optimizing their average performance over a large ensemble of future states of the world (SOW). Our approach exploits information gained over time, updating prior beliefs about the kind of SOW being experienced. We first run the standard DPS approach multiple times, but with varying sets of weights applied to the SOWs when calculating average performance. Adaptive "metapolicies" then further improve performance by specifying how control of the system should switch between policies identified using different weight sets, depending on our updated beliefs about the relative likelihood of being in certain SOWs. We outline the general method and illustrate it using a case study of efficient dike heightening that simultaneously minimizes protection system costs and flood damage resulting from rising sea levels and storm surge. The solutions identified by our adaptive algorithm dominate the standard DPS on these two objectives, with an average marginal damage reduction of 35.1% for policies with similar costs; improvements are largest in SOWs with relatively lower sea level rise. We also evaluate how performance varies under different ways of implementing the algorithm, such as changing the frequency with which beliefs are updated.

DNA Methylation Near DLGAP2 May Mediate the Relationship between Family History of Type 1 Diabetes and Type 1 Diabetes Risk.

Given the differential risk of type 1 diabetes (T1D) in offspring of affected fathers versus affected mothers and our observation that T1D cases have differential DNA methylation near the imprinted DLGAP2 gene compared to controls, we examined whether methylation near DLGAP2 mediates the association between T1D family history and T1D risk. In a nested case-control study of 87 T1D cases and 87 controls from the Diabetes Autoimmunity Study in the Young, we conducted causal mediation analyses at 12 DLGAP2 region CpGs to decompose the effect of family history on T1D risk into indirect and direct effects. These effects were estimated from two regression models adjusted for the human leukocyte antigen DR3/4 genotype: a linear regression of family history on methylation (mediator model) and a logistic regression of family history and methylation on T1D (outcome model). For 8 of the 12 CpGs, we identified a significant interaction between T1D family history and methylation on T1D risk. Accounting for this interaction, we found that the increased risk of T1D for children with affected mothers compared to those with no family history was mediated through differences in methylation at two CpGs (cg27351978, cg00565786) in the DLGAP2 region, as demonstrated by a significant pure natural indirect effect (odds ratio (OR) = 1.98, 95% confidence interval (CI): 1.06-3.71) and nonsignificant total natural direct effect (OR = 1.65, 95% CI: 0.16-16.62) (for cg00565786). In contrast, the increased risk of T1D for children with an affected father or sibling was not explained by DNA methylation changes at these CpGs. Results were similar for cg27351978 and robust in sensitivity analyses. Lastly, we found that DNA methylation in the DLGAP2 region was associated (P<0:05) with gene expression of nearby protein-coding genes DLGAP2, ARHGEF10, ZNF596, and ERICH1. Results indicate that the maternal protective effect conferred through exposure to T1D in utero may operate through changes to DNA methylation that have functional downstream consequences.

Maximizing Well-Being in the Context of Long-Term Services and Supports: A Q Methodological Approach.

OBJECTIVES: The goal of this study was to investigate diversity in stakeholders' perspectives on how best to maximize older adults' well-being when they use long-term services and supports (LTSS). METHODS: We used Q methodology, an exploratory method, to investigate preference patterns among a purposive sample of older adults, family members, and leadership professionals (n = 57). Participants categorized 52 items related to 9 domains of LTSS quality relevant to well-being into categories of importance. We used factors analysis and qualitative methods to identify groups of individuals who identified similar priorities. RESULTS: The analysis identified four shared viewpoints, each prioritizing different aspects of well-being: 1) physical health and safety; 2) independence; 3) emotional well-being; and 4) social engagement. Individual and contextual factors, including stakeholder role, care needs, and expectations for LTSS, appeared to influence participants' perspectives. CONCLUSIONS: Distinct viewpoints on how to maximize well-being when older adults use LTSS exist. Our results affirm the importance of person-centered care yet demonstrate that shared preference patterns LTSS exist. CLINICAL IMPLICATIONS: Engaging with older adults' values and preferences is critical to improving their experiences with LTSS. Better understanding common preference patterns could help providers deliver person-centered care more efficiently and effectively.

Integrated Risk Assessment and Management Methods Are Necessary for Effective Implementation of Natural Hazards Policy.

A transdisciplinary, integrated risk assessment and risk management process is particularly beneficial to the development of policies addressing risk from natural hazards. Strategies based on isolated risk assessment and management processes, guided by traditional "predict, then act" methods for decision making, may induce major regret if future conditions diverge from predictions. Analytic methods designed to identify robust solutions-those that perform satisfactorily over a broader range of future conditions-are more suitable for management of natural hazards risks, for at least three major reasons discussed within. Such approaches benefit from co-production of knowledge to collaboratively produce adaptive, robust policies through an iterative process of dialogue between analysts, decisionmakers, and other stakeholders: exploring tradeoffs, searching for futures in which current plans are likely to fail, and developing adaptive management strategies responsive to evolving future conditions. The process leads to more effective adoption of risk management policies by ensuring greater feasibility of solutions, exploring a wide range of plausible future conditions, generating buy-in, and giving a voice to actors with a diversity of perspectives. The second half of the article presents Louisiana's coastal master planning process as an exemplary model of participatory planning and integrated risk assessment and management. Louisiana planners have adopted a decision framework that incorporates insights from modern methods for decision making under deep uncertainty to effectively address the deep uncertainties and complexities characteristic of a variety of natural hazards and long-range planning problems.

Prioritizing LTSS Quality: Exploring the Views of Older Adults, Families, and Professionals.

We conducted a cross-sectional survey involving 349 older adults, family members, and long-term services and supports (LTSS) professionals in Minnesota to assess their views on priorities for residential LTSS quality. We found considerable agreement among the three groups on the highest priorities to ensure the wellbeing of older adults who use LTSS: safety, dignity, and staffing. Relationships were also viewed as a high priority. However, older adults prioritized the physical environment over professionals, and they expressed more varied opinions on priorities overall. Older adults also consistently rated autonomy/choice as less important than other quality domains, a finding worth further exploration.

A brief guide for the measurement and interpretation of microbial functional diversity.

The importance of functional diversity for the functioning and behaviour of microbial communities is clear, yet the widespread incorporation of functional diversity measurements into environmental microbiology study designs remains surprisingly limited. This may, at least to some extent, be a consequence of the unique conceptual and methodological challenges to measuring functional diversity in microbial communities. To facilitate the increased incorporation of functional diversity measurements into environmental microbiology study designs, we review here the process and some key caveats for measuring functional diversity and provide specific examples. We highlight three main decision points and provide guidance to making these decisions based on the underlying mechanisms for how functional diversity relates to an ecosystem process or property of interest. We discuss the selection of an appropriate type of functional trait, selection of the specificity at which functional diversity will be measured, and selection of an appropriate metric for estimating functional diversity from quantitative measures of those traits. We further discuss decisions regarding the use of one- or multi-dimensional measures of functional diversity and how advances in the field of trait-based community ecology could be applied or adapted to address questions in environmental microbiology.

Relating Metatranscriptomic Profiles to the Micropollutant Biotransformation Potential of Complex Microbial Communities.

Biotransformation of chemical contaminants is of importance in various natural and engineered systems. However, in complex microbial communities and with chemical contaminants at low concentrations, our current understanding of biotransformation at the level of enzyme-chemical interactions is limited. Here, we explored an approach to identify associations between micropollutant biotransformation and specific gene products in complex microbial communities, using association mining between chemical and metatranscriptomic data obtained from experiments with activated sludge grown at different solid retention times. We successfully demonstrate proportional relationships between the measured rate constants and associated gene transcripts for nitrification as a major community function, but also for the biotransformation of two nitrile-containing micropollutants (bromoxynil and acetamiprid) and transcripts of nitrile hydratases, a class of enzymes that we experimentally confirmed to produce the detected amide transformation products. As these results suggest that metatranscriptomic information can indeed be quantitatively correlated with low abundant community functions such as micropollutant biotransformation in complex microbial communities, we proceeded to explore the potential of association mining to highlight enzymes likely involved in catalyzing less well-understood micropollutant biotransformation reactions. Specifically, we use the cases of nitrile hydration and oxidative biotransformation reactions to show that the consideration of additional experimental evidence (such as information on biotransformation pathways) increases the likelihood of detecting plausible novel enzyme-chemical relationships. Finally, we identify a cluster of mono- and dioxygenase fourth-level enzyme classes that most strongly correlate with oxidative micropollutant biotransformation reactions in activated sludge.

Achieving presence in film and psychotherapy.

Film-makers have had to learn how to manipulate static images in both time and space to create an illusion of presence for their audiences. Film editors have discovered the importance of shot length in keeping audiences' attention and evoking various emotions of suspense, confusion, and excitement. Cinematographers shape the experience of witnessing through subjective and objective camera angles, positioning the audience in empty space or inside a character. For psychotherapists who attempt to "be present" for their clients, without the tools of the film editor or cinematographer, achieving presence can be quite an undertaking. Psychotherapists continuously mark their presence with "mm-hmms" or nods, and they depart the moment to think about and prepare what they will say, without appearing as if they have done so. Unlike film, which stabilizes the relationship between subject and object, psychotherapy embraces the unstable dance of the interpersonal encounter. Nevertheless, in the end, a good film and a good psychotherapy session are able to overcome the barriers to presence and bring us together in a colocated state of consciousness.

Substrate cross-feeding affects the speed and trajectory of molecular evolution within a synthetic microbial assemblage.

BACKGROUND: Substrate cross-feeding occurs when one organism partially consumes a primary substrate into one or more metabolites while other organisms then consume the metabolites. While pervasive within microbial communities, our knowledge about the effects of substrate cross-feeding on microbial evolution remains limited. To address this knowledge gap, we experimentally evolved isogenic nitrite (NO2-) cross-feeding microbial strains together for 700 generations, identified genetic changes that were acquired over the evolution experiment, and compared the results with an isogenic completely denitrifying strain that was evolved alone for 700 generations. We further investigated how the magnitude of interdependence between the nitrite cross-feeding strains affects the main outcomes. Our main objective was to quantify how substrate cross-feeding and the magnitude of interdependence affect the speed and trajectory of molecular evolution. RESULTS: We found that each nitrite (NO2-) cross-feeding strain acquired fewer genetic changes than did the completely denitrifying strain. In contrast, pairs of nitrite cross-feeding strains together acquired more genetic changes than did the completely denitrifying strain. Moreover, nitrite cross-feeding promoted population diversification, as pairs of nitrite cross-feeding strains acquired a more varied set of genetic changes than did the completely denitrifying strain. These outcomes likely occurred because nitrite cross-feeding enabled the co-existence of two distinct microbial strains, thus increasing the amount of genetic variation for selection to act upon. Finally, the nitrite cross-feeding strains acquired different types of genetic changes than did the completely denitrifying strain, indicating that nitrite cross-feeding modulates the trajectory of molecular evolution. CONCLUSIONS: Our results demonstrate that substrate cross-feeding can affect both the speed and trajectory of molecular evolution within microbial populations. Substrate cross-feeding can therefore have potentially important effects on the life histories of microorganisms.

Improved Methods for Estimating Flood Depth Exceedances Within Storm Surge Protection Systems.

Contemporary studies conducted by the U.S. Army Corps of Engineers estimate probability distributions of flooding on the interior of ring levee systems by estimating surge exceedances at points along levee system boundaries, calculating overtopping volumes generated by this surface, then passing the resulting volumes of water through a drainage model to calculate interior flood depths. This approach may not accurately represent the exceedance probability of flood depths within the system interior; a storm producing 100-year surge at one point is unlikely to simultaneously produce 100-year surge levels everywhere around the system exterior. A conceptually preferred approach estimates surge and waves associated with a large set of storms. Each storm is run through the interior model separately, and the resulting flood depths are weighted by a parameterized likelihood of each synthetic storm. This results in an empirical distribution of flood depths accounting for geospatial variation in any individual storm's characteristics. This method can also better account for the probability of levee breaches or other system failures. The two methods can produce different estimates of flood depth exceedances and damage when applied to storm surge flooding in coastal Louisiana. Even differences in flood depth exceedances of less than 0.2 m can still produce large differences in projected damage. This article identifies and discusses differences in estimated flood depths and damage produced by each method within multiple Louisiana protection systems. The novel coupled dynamics approach represents a step toward enabling risk-based design standards.

Analysis of diagnostic data for sexually transmissible infections in South Australian Aboriginal Community Controlled Health Services (2008-16).

Australian Aboriginal communities experience a high burden of sexually transmissible infections (STIs). Since 2009, a comprehensive sexual health program has been implemented at nine Aboriginal Community Controlled Health Services in South Australia. This study assessed trends in STI testing and positivity using deidentified diagnostic data from this period (2008-16). METHODS: Testing data for Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and Trichomonas vaginalis (TV) from one urban, three regional and five remote Aboriginal health services were analysed using logistic regression. RESULTS: From 2008 to 2016, testing increased for CT (twofold), NG (threefold) and TV (sixfold). On average, 30% of testing occurred during an annual 6-week screen. Fewer males were tested (range 27-38% annually). Mean annual STI testing coverage was 28% for 16- to 30-year-old clients attending regional or remote services (2013-16). Positivity at first testing episode for all three infections declined during the study period. From 2013 to 2016, when testing was stable and changes in positivity were more likely to indicate changes in prevalence, there were significant reductions in CT positivity (adjusted odds ratio (aOR) 0.4; 95% confidence interval (CI) 0.2-0.5) and TV positivity (aOR 0.6, 95% CI 0.4-0.9), although declines were statistically significant for females only. There was no significant decrease in NG positivity (aOR 0.9; 95% CI 0.5-1.5). CONCLUSIONS: Since the sexual health program began, STI testing increased and STI positivity declined, but significant reductions observed in CT and TV positivity were confined to females. These findings suggest evidence of benefit from sustained, comprehensive sexual health programs in Aboriginal communities with a high STI prevalence, but highlight the need to increase STI testing among men in these communities.

Generality of associations between biological richness and the rates of metabolic processes across microbial communities.

Biological richness is positively associated with the rates of some metabolic processes performed by microbial communities. It remains unclear, however, whether these positive associations are a general feature of the metabolic processes performed by microbial communities or whether they are specific to certain types of metabolic processes. For example, it was hypothesized that the strength of any particular positive association depends on how many different genotypes within a microbial community perform the metabolic process of interest (i.e. the 'rarity hypothesis'). We tested the generality of these positive associations by measuring the taxonomic richness, functional gene richness and rate constants for 71 different metabolic processes across 30 independent microbial communities. We found that both taxonomic and functional gene richness do indeed tend to positively associate with the rates of metabolic processes. In addition, we found that positive associations occur across a wide range of different environmental conditions. Counter to the 'rarity hypothesis', however, we did not detect a relationship between the strengths of the positive associations and the rarity of each metabolic process. Together, our data provide empirical evidence that positive associations with biological richness may indeed be a general feature of the metabolic processes performed by microbial communities.

Metabolite toxicity determines the pace of molecular evolution within microbial populations.

BACKGROUND: The production of toxic metabolites has shaped the spatial and temporal arrangement of metabolic processes within microbial cells. While diverse solutions to mitigate metabolite toxicity have evolved, less is known about how evolution itself is affected by metabolite toxicity. We hypothesized that the pace of molecular evolution should increase as metabolite toxicity increases. At least two mechanisms could cause this. First, metabolite toxicity could increase the mutation rate. Second, metabolite toxicity could increase the number of available mutations with large beneficial effects that selection could act upon (e.g., mutations that provide tolerance to toxicity), which consequently would increase the rate at which those mutations increase in frequency. RESULTS: We tested this hypothesis by experimentally evolving the bacterium Pseudomonas stutzeri under denitrifying conditions. The metabolite nitrite accumulates during denitrification and has pH-dependent toxic effects, which allowed us to evolve P. stutzeri at different magnitudes of nitrite toxicity. We demonstrate that increased nitrite toxicity results in an increased pace of molecular evolution. We further demonstrate that this increase is generally due to an increased number of available mutations with large beneficial effects and not to an increased mutation rate. CONCLUSIONS: Our results demonstrate that the production of toxic metabolites can have important impacts on the evolutionary processes of microbial cells. Given the ubiquity of toxic metabolites, they could also have implications for understanding the evolutionary histories of biological organisms.

A passive mutualistic interaction promotes the evolution of spatial structure within microbial populations.

BACKGROUND: While mutualistic interactions between different genotypes are pervasive in nature, their evolutionary origin is not clear. The dilemma is that, for mutualistic interactions to emerge and persist, an investment into the partner genotype must pay off: individuals of a first genotype that invest resources to promote the growth of a second genotype must receive a benefit that is not equally accessible to individuals that do not invest. One way for exclusive benefits to emerge is through spatial structure (i.e., physical barriers to the movement of individuals and resources). RESULTS: Here we propose that organisms can evolve their own spatial structure based on physical attachment between individuals, and we hypothesize that attachment evolves when spatial proximity to members of another species is advantageous. We tested this hypothesis using experimental evolution with combinations of E. coli strains that depend on each other to grow. We found that attachment between cells repeatedly evolved within 8 weeks of evolution and observed that many different types of mutations potentially contributed to increased attachment. CONCLUSIONS: We postulate a general principle by which passive beneficial interactions between organisms select for attachment, and attachment then provides spatial structure that could be conducive for the evolution of active mutualistic interactions.

Uptake Kinetics and Trophic Transfer of Tungsten from Cabbage to a Herbivorous Animal Model.

This investigation builds on previous studies on military-relevant tungsten (W) to more thoroughly explore environmental pathways and bioaccumulation kinetics during direct soil exposure versus trophic transfer and elucidate its relative accumulation and speciation in different snail organs. The modeled steady-state concentration and bioaccumulation factor (BAF) of W from soil into cabbage were 302 mg/kg and 0.55, respectively. Steady-state concentrations (34 mg/kg) and BAF values (0.05) obtained for the snail directly exposed to contaminated soil were lower than trophic transfer by consumption of W-contaminated cabbage (tissue concentration of 86 mg/kg; BAF of 0.36). Thus, consumption of contaminated food is the most important pathway for W mobility in this food chain. The highest concentrations of W compartmentalization were in the snail's hepatopancreas based on wet chemistry and synchrotron-based investigations. Chemical speciation via inductively couple plasma mass spectrometry showed a higher degree of polytungstate partitioning in the hepatopancreas relative to the rest of the body. Based on synchrotron analysis, W was incorporated into the shell matrix during exposure, particularly during the regeneration of damaged shell. This offers the potential for application of the shell as a longer-term biomonitoring and forensics tool for historic exposure.

Social Cognition, Child Neglect, and Child Injury Risk: The Contribution of Maternal Social Information Processing to Maladaptive Injury Prevention Beliefs Within a High-Risk Sample.

Objective: Inadequate supervision has been linked to children's injuries. Parental injury prevention beliefs may play a role in supervision, yet little theory has examined the origins of such beliefs. This study examined whether mothers who perpetrated child neglect, who as a group provide inadequate supervision, have more maladaptive beliefs. Then, it tested a social information processing (SIP) model for explaining these beliefs. Methods: SIP and injury prevention beliefs were assessed in disadvantaged mothers of preschoolers (N = 145), half with child neglect histories. Results: The neglect group exhibited significantly more maladaptive injury prevention beliefs than comparisons. As predicted, SIP was linked to beliefs that may increase injury risk, even after accounting for relevant sociodemographic variables. Conclusions: Findings support the link of beliefs to injury risk and suggest that specific cognitive problems may underlie these beliefs. Future work should further validate this model, which may inform enhancements to prevention efforts.

Predicting chemical bioavailability using microarray gene expression data and regression modeling: A tale of three explosive compounds.

BACKGROUND: Chemical bioavailability is an important dose metric in environmental risk assessment. Although many approaches have been used to evaluate bioavailability, not a single approach is free from limitations. Previously, we developed a new genomics-based approach that integrated microarray technology and regression modeling for predicting bioavailability (tissue residue) of explosives compounds in exposed earthworms. In the present study, we further compared 18 different regression models and performed variable selection simultaneously with parameter estimation. RESULTS: This refined approach was applied to both previously collected and newly acquired earthworm microarray gene expression datasets for three explosive compounds. Our results demonstrate that a prediction accuracy of R(2) = 0.71-0.82 was achievable at a relatively low model complexity with as few as 3-10 predictor genes per model. These results are much more encouraging than our previous ones. CONCLUSION: This study has demonstrated that our approach is promising for bioavailability measurement, which warrants further studies of mixed contamination scenarios in field settings.

Biotransformation of Two Pharmaceuticals by the Ammonia-Oxidizing Archaeon Nitrososphaera gargensis.

The biotransformation of some micropollutants has previously been observed to be positively associated with ammonia oxidation activities and the transcript abundance of the archaeal ammonia monooxygenase gene (amoA) in nitrifying activated sludge. Given the increasing interest in and potential importance of ammonia-oxidizing archaea (AOA), we investigated the capabilities of an AOA pure culture, Nitrososphaera gargensis, to biotransform ten micropollutants belonging to three structurally similar groups (i.e., phenylureas, tertiary amides, and tertiary amines). N. gargensis was able to biotransform two of the tertiary amines, mianserin (MIA) and ranitidine (RAN), exhibiting similar compound specificity as two ammonia-oxidizing bacteria (AOB) strains that were tested for comparison. The same MIA and RAN biotransformation reactions were carried out by both the AOA and AOB strains. The major transformation product (TP) of MIA, α-oxo MIA was likely formed via a two-step oxidation reaction. The first hydroxylation step is typically catalyzed by monooxygenases. Three RAN TP candidates were identified from nontarget analysis. Their tentative structures and possible biotransformation pathways were proposed. The biotransformation of MIA and RAN only occurred when ammonia oxidation was active, suggesting cometabolic transformations. Consistently, a comparative proteomic analysis revealed no significant differential expression of any protein-encoding gene in N. gargensis grown on ammonium with MIA or RAN compared with standard cultivation on ammonium only. Taken together, this study provides first important insights regarding the roles played by AOA in micropollutant biotransformation.

IMPAIRED FERTILITY AND PERCEIVED DIFFICULTIES CONCEIVING IN GHANA: MEASUREMENT PROBLEMS AND PROSPECTS.

What is the most appropriate measure of impaired fertility for understanding its social consequences in sub-Saharan Africa? The dearth of subjective measures in surveys in the region has prevented comparisons of subjective and objective measures. Perceived difficulties conceiving may have a greater impact than objective measures for social outcomes such as divorce, stigmatization and distress. This study compares 12- (clinical) and 24- (epidemiological) month measures from biomedicine and 5- and 7-year measures from demography with a subjective measure of impaired fertility using correlations, random effects models and test-retest models to assess relationships between measures, their association with sociodemographic characteristics and the stability of measures across time. Secondary panel data (1998-2004) from 1350 Ghanaian women aged 15-49 of all marital statuses are used. Longer waiting times to identification of impaired fertility required by demographic measures result in more stable measures, but perceived difficulties conceiving are most closely aligned with clinical infertility (r=0.61; p<0.05). Epidemiological infertility is also closely aligned with the subjective measure. A large proportion of those identified as having impaired fertility based purely on waiting times are successful contraceptors. Where subjective measures are not available, epidemiological (24-month) measures may be most appropriate for studies of the social consequences of impaired fertility. Accounting for contraceptive use is important in order to avoid false positives. Future research should consider a variety of measures of perceived difficulties conceiving and self-identified infertility to assess which is most valid; in order to accomplish this, it is imperative that subjective measures of infertility be included in social surveys in sub-Saharan Africa.