Engineered transcription-associated Cas9 targeting in eukaryotic cells.

DNA targeting Class 2 CRISPR-Cas effector nucleases, including the well-studied Cas9 proteins, evolved protospacer-adjacent motif (PAM) and guide RNA interactions that sequentially license their binding and cleavage activities at protospacer target sites. Both interactions are nucleic acid sequence specific but function constitutively; thus, they provide intrinsic spatial control over DNA targeting activities but naturally lack temporal control. Here we show that engineered Cas9 fusion proteins which bind to nascent RNAs near a protospacer can facilitate spatiotemporal coupling between transcription and DNA targeting at that protospacer: Transcription-associated Cas9 Targeting (TraCT). Engineered TraCT is enabled when suboptimal PAM interactions limit basal activity in vivo and when one or more nascent RNA substrates are still tethered to the actively transcribing target DNA in cis. We further show that this phenomenon can be exploited for selective editing at one of two identical targets in distinct gene loci, or, in diploid allelic loci that are differentially transcribed. Our work demonstrates that temporal control over Cas9's targeting activity at specific DNA sites may be engineered without modifying Cas9's core domains and guide RNA components or their expression levels. More broadly, it establishes RNA binding in cis as a mechanism that can conditionally stimulate CRISPR-Cas DNA targeting in eukaryotes.

Single inhalation exposure to polyamide micro and nanoplastic particles impairs vascular dilation without generating pulmonary inflammation in virgin female Sprague Dawley rats.

BACKGROUND: Exposure to micro- and nanoplastic particles (MNPs) in humans is being identified in both the indoor and outdoor environment. Detection of these materials in the air has made inhalation exposure to MNPs a major cause for concern. One type of plastic polymer found in indoor and outdoor settings is polyamide, often referred to as nylon. Inhalation of combustion-derived, metallic, and carbonaceous aerosols generate pulmonary inflammation, cardiovascular dysfunction, and systemic inflammation. Additionally, due to the additives present in plastics, MNPs may act as endocrine disruptors. Currently there is limited knowledge on potential health effects caused by polyamide or general MNP inhalation. OBJECTIVE: The purpose of this study is to assess the toxicological consequences of a single inhalation exposure of female rats to polyamide MNP during estrus by means of aerosolization of MNP. METHODS: Bulk polyamide powder (i.e., nylon) served as a representative MNP. Polyamide aerosolization was characterized using particle sizers, cascade impactors, and aerosol samplers. Multiple-Path Particle Dosimetry (MPPD) modeling was used to evaluate pulmonary deposition of MNPs. Pulmonary inflammation was assessed by bronchoalveolar lavage (BAL) cell content and H&E-stained tissue sections. Mean arterial pressure (MAP), wire myography of the aorta and uterine artery, and pressure myography of the radial artery was used to assess cardiovascular function. Systemic inflammation and endocrine disruption were quantified by measurement of proinflammatory cytokines and reproductive hormones. RESULTS: Our aerosolization exposure platform was found to generate particles within the micro- and nano-size ranges (thereby constituting MNPs). Inhaled particles were predicted to deposit in all regions of the lung; no overt pulmonary inflammation was observed. Conversely, increased blood pressure and impaired dilation in the uterine vasculature was noted while aortic vascular reactivity was unaffected. Inhalation of MNPs resulted in systemic inflammation as measured by increased plasma levels of IL-6. Decreased levels of 17ß-estradiol were also observed suggesting that MNPs have endocrine disrupting activity. CONCLUSIONS: These data demonstrate aerosolization of MNPs in our inhalation exposure platform. Inhaled MNP aerosols were found to alter inflammatory, cardiovascular, and endocrine activity. These novel findings will contribute to a better understanding of inhaled plastic particle toxicity.

A universal deep-learning model for zinc finger design enables transcription factor reprogramming.

Cys2His2 zinc finger (ZF) domains engineered to bind specific target sequences in the genome provide an effective strategy for programmable regulation of gene expression, with many potential therapeutic applications. However, the structurally intricate engagement of ZF domains with DNA has made their design challenging. Here we describe the screening of 49 billion protein-DNA interactions and the development of a deep-learning model, ZFDesign, that solves ZF design for any genomic target. ZFDesign is a modern machine learning method that models global and target-specific differences induced by a range of library environments and specifically takes into account compatibility of neighboring fingers using a novel hierarchical transformer architecture. We demonstrate the versatility of designed ZFs as nucleases as well as activators and repressors by seamless reprogramming of human transcription factors. These factors could be used to upregulate an allele of haploinsufficiency, downregulate a gain-of-function mutation or test the consequence of regulation of a single gene as opposed to the many genes that a transcription factor would normally influence.

Towards implementing artificial intelligence post-processing in weather and climate: proposed actions from the Oxford 2019 workshop.

The most mature aspect of applying artificial intelligence (AI)/machine learning (ML) to problems in the atmospheric sciences is likely post-processing of model output. This article provides some history and current state of the science of post-processing with AI for weather and climate models. Deriving from the discussion at the 2019 Oxford workshop on Machine Learning for Weather and Climate, this paper also presents thoughts on medium-term goals to advance such use of AI, which include assuring that algorithms are trustworthy and interpretable, adherence to FAIR data practices to promote usability, and development of techniques that leverage our physical knowledge of the atmosphere. The coauthors propose several actionable items and have initiated one of those: a repository for datasets from various real weather and climate problems that can be addressed using AI. Five such datasets are presented and permanently archived, together with Jupyter notebooks to process them and assess the results in comparison with a baseline technique. The coauthors invite the readers to test their own algorithms in comparison with the baseline and to archive their results. This article is part of the theme issue 'Machine learning for weather and climate modelling'.

Dynamic 3-D Visualization of Climate Model Development and Results.

Climate models play a significant role in the understanding of climate change, and the effective presentation and interpretation of their results is important for both the scientific community and the general public. In the case of the latter audience-which has become increasingly concerned with the implications of climate change for society-there is a requirement for visualizations which are compelling and engaging. We describe the use of ParaView, a well-established visualization application, to produce images and animations of results from a large set of modeling experiments, and their use in the promulgation of climate research results. Visualization can also make useful contributions to development, particularly for complex large-scale applications such as climate models. We present early results from the construction of a next-generation climate model which has been designed for use on exascale compute platforms, and show how visualization has helped in the development process, particularly with regard to higher model resolutions and novel data representations.

Right Ventricular Strain, Brain Natriuretic Peptide, and Mortality in Congenital Diaphragmatic Hernia.

Rationale: Brain-type natriuretic peptide (BNP) correlates with pulmonary hypertension as demonstrated by echocardiogram in congenital diaphragmatic hernia (CDH); however, its association with right ventricular (RV) function and mortality is unknown.Objectives: To characterize the relationships between echocardiogram-derived RV strain, BNP, and mortality in diaphragmatic hernia.Methods: We performed a single-center retrospective cohort study of infants with CDH and at least one BNP-echocardiogram pair within a 24-hour period. RV global longitudinal strain (GLS) and free-wall strain (FWS) were measured on existing echocardiograms. Associations among strain, BNP, and mortality were tested using mixed-effect linear and logistic regression models. Survival analysis was stratified by BNP and strain abnormalities.Results: There were 220 infants with 460 BNP-echocardiogram pairs obtained preoperatively (n = 237), ≤1 week postoperatively (n = 35), and >1 week postoperatively ("recovery"; n = 188). Strain improved after repair (P < 0.0001 for all periods). Higher BNP level was associated with worse strain in recovery but not before or immediately after operation (estimate [95% confidence interval] for recovery: GLS, 1.03 [0.50-1.57]; P = 0.0003; FWS, 0.62 [0.01-1.22]; P = 0.047). BNP and strain abnormalities were associated with an extracorporeal-membrane oxygenation requirement. Higher BNP level in recovery was associated with greater mortality (odds ratio, 11.2 [1.2-571.3]; P = 0.02). Abnormal strain in recovery had high sensitivity for detection of mortality (100% for GLS; 100% for FWS) but had low specificity for detection of mortality (28% for GLS; 48% for FWS).Conclusions: Persistent RV dysfunction after CDH repair may be detected by a high BNP level and abnormal RV strain.

Sex- and age-dependent effects of maternal organophosphate flame-retardant exposure on neonatal hypothalamic and hepatic gene expression.

After the phase-out of polybrominated diphenyl ethers, their replacement compounds, organophosphate flame retardants (OPFRs) became ubiquitous in home and work environments. OPFRs, which may act as endocrine disruptors, are detectable in human urine, breast milk, and blood samples collected from pregnant women. However, the effects of perinatal OPFR exposure on offspring homeostasis and gene expression remain largely underexplored. To address this knowledge gap, virgin female mice were mated and dosed with either a sesame oil vehicle or an OPFR mixture (tris(1,3-dichloro-2-propyl)phosphate, tricresyl phosphate, and triphenyl phosphate, 1 mg/kg each) from gestational day (GD) 7 to postnatal day (PND) 14. Hypothalamic and hepatic tissues were collected from one female and one male pup per litter on PND 0 and PND 14. Expression of genes involved in energy homeostasis, reproduction, glucose metabolism, and xenobiotic metabolism were analyzed using quantitative real-time PCR. In the mediobasal hypothalamus, OPFR increased Pdyn, Tac2, Esr1, and Pparg in PND 14 females. In the liver, OPFR increased Pparg and suppressed Insr, G6pc, and Fasn in PND 14 males and increased Esr1, Foxo1, Dgat2, Fasn, and Cyb2b10 in PND 14 females. We also observed striking sex differences in gene expression that were dependent on the age of the pup. Collectively, these data suggest that maternal OPFR exposure alters hypothalamic and hepatic development by influencing neonatal gene expression in a sex-dependent manner. The long-lasting consequences of these changes in expression may disrupt puberty, hormone sensitivity, and metabolism of glucose, fatty acids, and triglycerides in the maturing juvenile.

Inhaled Nitric Oxide Is Associated with Improved Oxygenation in a Subpopulation of Infants with Congenital Diaphragmatic Hernia and Pulmonary Hypertension.

OBJECTIVES: To determine which patients with congenital diaphragmatic hernia (CDH) and pulmonary hypertension (PH) benefit from inhaled nitric oxide (iNO) treatment by comparing characteristics and outcomes of iNO responders to nonresponders. STUDY DESIGN: We performed a retrospective chart review of infants with CDH treated at our center between 2011 and 2016. In a subset of patients, iNO was initiated for hypoxemia or echocardiographic evidence of extrapulmonary right to left shunting. Initial post-treatment blood gases were reviewed, and patients were classified as responders (increased PaO2 >20 mm Hg) or nonresponders. Baseline characteristics, echocardiograms and outcomes were compared between groups with Fisher exact tests and Mann-Whitney t tests, as appropriate. RESULTS: During the study period, 95 of 131 patients with CDH (73%) were treated with iNO. All patients with pretreatment echocardiograms (n = 90) had echocardiographic evidence of PH. Thirty-eight (40%) patients met treatment response criteria. Responders had significant improvements in PaO2 (51 ± 3 vs 123 ± 7 mm Hg, P < .01), alveolar-arterial gradient (422 ± 30 vs 327 ± 27 mm Hg, P < .01), and PaO2 to FiO2 ratio (82 ± 10 vs 199 ± 15 mm Hg, P < .01). Nonresponders were more likely to have left ventricular systolic dysfunction (27% vs 8%, P = .03) on echocardiogram. Responders were less likely to require extracorporeal membrane support (50 vs 24%, P = .02). CONCLUSIONS: iNO treatment is associated with improved oxygenation and reduced need for ECMO in a subpopulation of patients with CDH with PH and normal left ventricular systolic function.

Autism spectrum disorder and neurodevelopmental delays in children with giant omphalocele.

OBJECTIVE: To determine the prevalence and identify risk factors of autism spectrum disorders (ASDs) and neurodevelopmental delays in giant omphalocele (GO) survivors. MATERIALS AND METHODS: The study cohort consists of 47 GO survivors enrolled in our follow-up program between 07/2004 and 12/2015. All patients underwent assessments at 2 years of age or older. Outcomes were assessed by either the Bayley Scales of Infant Development II (prior 2006) or III (after 2006), or the Wechsler Preschool and Primary Scale of Intelligence (children older than 4 years). ASD diagnosis was made based on the Diagnostic and Statistical Manual of Mental Disorders IV (prior to 2014) or 5 criteria. RESULTS: The prevalence of ASD in GO children is 16 times higher than the general population (P = 0.0002). ASD patients were more likely to be diagnosed with neurodevelopmental and neurofunctional delays, language disorders, and genetic abnormalities (P < 0.01). While 53.2% of GO children scored within the average range for all developmental domains, 19.1% scored within the mildly delayed and 27.7% in the severe delayed range in at least one domain. Prolonged respiratory support, pulmonary hypertension, gastroesophageal reflux disease, feeding problems, prolonged hospitalization, abnormal BAER hearing screen, presence of delayed motor coordination, and hypotonicity were associated with delayed scores (P < 0.05). CONCLUSIONS: There is a significant rate of ASD in GO survivors. Neurodevelopmental delays, language delays, and genetic abnormalities were strongly associated with ASD. Neurological impairments were present in nearly half of GO children. Surrogate markers of disease severity were associated with below average neurodevelopmental scores. Level of evidence Level IV.

Congenital diaphragmatic hernia sacs: prenatal imaging and associated postnatal outcomes.

BACKGROUND: The presence of a hernia sac in congenital diaphragmatic hernia (CDH) has been reported to be associated with higher lung volumes and better postnatal outcomes. OBJECTIVE: To compare prenatal imaging (ultrasound and MRI) prognostic measurements and postnatal outcomes of CDH with and without hernia sac. MATERIALS AND METHODS: We performed database searches from January 2008 to March 2017 for surgically proven cases of CDH with and without hernia sac. All children had a detailed ultrasound (US) examination and most had an MRI examination. We reviewed the medical records of children enrolled in our Pulmonary Hypoplasia Program. RESULTS: Of 200 cases of unilateral CDH, 46 (23%) had hernia sacs. Cases of CDH with hernia sac had a higher mean lung-to-head ratio (LHR; 1.61 vs. 1.17; P<0.01), a higher mean observed/expected LHR (0.49 vs. 0.37; P<0.01), and on MRI a higher mean observed/expected total lung volume (0.53 vs. 0.41; P<0.01). Based on a smooth interface between lung and herniated contents, hernia sac or eventration was prospectively questioned by US and MRI in 45.7% and 38.6% of cases, respectively. Postnatally, hernia sac is associated with shorter median periods of admission to the neonatal intensive care unit (45.0 days vs. 61.5 days, P=0.03); mechanical ventilation (15.5 days vs. 23.5 days, P=0.04); extracorporeal membrane oxygenation (251 h vs. 434 h, P=0.04); decreased rates of patch repair (39.0% vs. 69.2%, P<0.01); and pulmonary hypertension (56.1% vs. 75.4%, P=0.03). CONCLUSION: Hernia sac is associated with statistically higher prenatal prognostic measurements and improved postnatal outcomes. Recognition of a sharp interface between lung and herniated contents may allow for improved prenatal diagnosis; however, delivery and management should still occur at experienced quaternary neonatal centers.

Behavioral Learning in a Cognitive Neuromorphic Robot: An Integrative Approach.

We present here a learning system using the iCub humanoid robot and the SpiNNaker neuromorphic chip to solve the real-world task of object-specific attention. Integrating spiking neural networks with robots introduces considerable complexity for questionable benefit if the objective is simply task performance. But, we suggest, in a cognitive robotics context, where the goal is understanding how to compute, such an approach may yield useful insights to neural architecture as well as learned behavior, especially if dedicated neural hardware is available. Recent advances in cognitive robotics and neuromorphic processing now make such systems possible. Using a scalable, structured, modular approach, we build a spiking neural network where the effects and impact of learning can be predicted and tested, and the network can be scaled or extended to new tasks automatically. We introduce several enhancements to a basic network and show how they can be used to direct performance toward behaviorally relevant goals. Results show that using a simple classical spike-timing-dependent plasticity (STDP) rule on selected connections, we can get the robot (and network) to progress from poor task-specific performance to good performance. Behaviorally relevant STDP appears to contribute strongly to positive learning: "do this" but less to negative learning: "don't do that." In addition, we observe that the effect of structural enhancements tends to be cumulative. The overall system suggests that it is by being able to exploit combinations of effects, rather than any one effect or property in isolation, that spiking networks can achieve compelling, task-relevant behavior.

Measures to assess the performance of an Australian non-government charitable non-acute health service: A Delphi Survey of Organisational Stakeholders.

Organisation performance measurement is relevant for non-profit charitable organisations as they strive for security in an increasingly competitive funding environment. This study aimed to identify the priority measures and indicators of organisational performance of an Australian non-government charitable organisation that delivers non-acute health services. Seventy-seven and 59 participants across nine stakeholder groups responded to a two-staged Delphi technique study of a case study organisation. The stage one questionnaire was developed using information garnered through a detailed review of literature. Data from the first round were aggregated and analysed for the stage two survey. The final data represented a group consensus. Quality of care was ranked the most important of six organisational performance measures. Service user satisfaction was ranked second followed by financial performance, internal processes, employee learning and growth and community engagement. Thirteen priority indicators were determined across the six measures. Consensus was reached on the priority organisational performance measures and indicators. Stakeholders of the case study organisation value evidence-based practice, technical strength of services and service user satisfaction over more commercially orientated indicators.

Co-constructed health narratives during a 'media event': The case of the first Dutch Twitter heart operation.

OBJECTIVE: This article examines the relationship between microblogging and the development of health narrative through the lens of an institution-initiated media event, the first live-tweeted heart operation in the Netherlands. It specifically addresses the question, how does health narrative take shape on a microblog and other (social) media, through the combination of self-initiated status updates, reactions to questions and short conversations with followers? METHODS: A combination of qualitative and quantitative data analysis was used to identify prominent themes in the tweets and trace the complex process by which the narrative took shape. The results presented here are derived from the qualitative analysis. RESULTS: There are four recurring health narrative themes in the tweets: (a) new challenges to professionalism; (b) mutual exchanges of information, support and advice; (c) increasingly personal (and public) details; and (d) questions about 'resuming normalcy'. The special nature of this case also reveals interesting features, such as the multiple narrative starting points and the phenomenon of 'tweeting by proxy', and raises a number of critical questions regarding this type of use of social media in healthcare. CONCLUSIONS: In the discussion we reflect on whether/how microblogged health narratives are really 'new' and on the implications of this single case for understanding the relationship between social media, health narrative and the changing relationships between information technologies, actors and institutions. We further examine this case as an example of what Lupton has deemed the 'digital patient experience economy', in reference to patients increasingly being encouraged to post experiences of their illness and encounters with the healthcare system to online platforms, where these shared experiences become valorised and monetised.

Impact of Medicare Part D on Racial and Ethnic Minorities.

OBJECTIVES: Prior to the implementation of Medicare Part D in the United States, inequalities were found to exist in the use of medications between minority and white beneficiaries. Despite improvements in medication affordability after Medicare Part D implementation, it is still not clear whether the characteristics of the program have improved drug utilization patterns among minorities to the same degree as whites. This review aims to determine whether there were barriers for Medicare Part D to realize its potential to improve prescription drug utilization patterns among minorities. METHODS: Google Scholar, PubMed, Sciencedirect and Scopus were used to conduct a comprehensive search of the literature published since 2003 when the Medicare Prescription Drug, Improvement, and Modernization Act (MMA) was passed, which authorized the establishment of the Part D program. All studies and documents related to the effects of Medicare Part D on minorities were included to present a relatively comprehensive review on the topic. RESULTS: Evidence indicated that minorities are not equally benefiting from Medicare Part D prescription drug coverage compared to whites. Examples of characteristics of Medicare Part D that caused significant racial differences in drug utilization include the donut hole, the complexity and number of drug plans, and drug utilization management strategies. CONCLUSION: Medicare Part D has increased access to prescription medications for the elderly. However, continued analysis and research of drug utilization patterns among minorities should be conducted to ensure that all enrollees regardless of race are benefiting equally from Medicare Part D. Identification of these barriers can provide insights on how to improve the program to allow minorities to benefit equally from the Medicare Part D program and remove health inequalities.

Precision medicine: opportunities, possibilities, and challenges for patients and providers.

Precision medicine approaches disease treatment and prevention by taking patients' individual variability in genes, environment, and lifestyle into account. Although the ideas underlying precision medicine are not new, opportunities for its more widespread use in practice have been enhanced by the development of large-scale databases, new methods for categorizing and representing patients, and computational tools for analyzing large datasets. New research methods may create uncertainty for both healthcare professionals and patients. In such situations, frameworks that address ethical, legal, and social challenges can be instrumental for facilitating trust between patients and providers, but must protect patients while not stifling progress or overburdening healthcare professionals. In this perspective, we outline several ethical, legal, and social issues related to the Precision Medicine Initiative's proposed changes to current institutions, values, and frameworks. This piece is not an exhaustive overview, but is intended to highlight areas meriting further study and action, so that precision medicine's goal of facilitating systematic learning and research at the point of care does not overshadow healthcare's goal of providing care to patients.

Proud2Bme: Exploratory research on care and control in young women's online eating disorder narratives.

Illness narratives have been studied to understand the patient's point of view. These narratives are becoming more prolific, accessible, and specialized, thanks to the improved Internet access and the growth of health-specific online communities. This article analyses illness narratives posted on a Dutch eating disorder website hosted by a treatment centre. Specifically, we look at 'care of the self' and 'control'. The young women wrote about controlling situations with disordered eating as a self-care tool, about being controlled by the disorder and about regaining control over the disorder. The website, with the opportunity for constant, unseen supervision, coercion through comments, and steering through edits and comments, revealed various modalities of control. While issues of control and eating disorders have been explored by others, little work has been done on how the control experienced by the young women (coercion on the individual, the body as the object of control, and the modality of pressure and supervision) interact, how control is presented in stories for a recovery-focused, monitored website, and how the website directs the content. As recovery-focused, therapist-led website is likely to continue growing, understanding how and why young women talk about care and control in the context of such websites is an important topic.

Seasonally adjusted birth frequencies follow the Poisson distribution.

BACKGROUND: Variations in birth frequencies have an impact on activity planning in maternity wards. Previous studies of this phenomenon have commonly included elective births. A Danish study of spontaneous births found that birth frequencies were well modelled by a Poisson process. Somewhat unexpectedly, there were also weekly variations in the frequency of spontaneous births. Another study claimed that birth frequencies follow the Benford distribution. Our objective was to test these results. MATERIAL AND METHOD: We analysed 50,017 spontaneous births at Akershus University Hospital in the period 1999-2014. To investigate the Poisson distribution of these births, we plotted their variance over a sliding average. We specified various Poisson regression models, with the number of births on a given day as the outcome variable. The explanatory variables included various combinations of years, months, days of the week and the digit sum of the date. RESULTS: The relationship between the variance and the average fits well with an underlying Poisson process. A Benford distribution was disproved by a goodness-of-fit test (p < 0.01). The fundamental model with year and month as explanatory variables is significantly improved (p < 0.001) by adding day of the week as an explanatory variable. Altogether 7.5% more children are born on Tuesdays than on Sundays. The digit sum of the date is non-significant as an explanatory variable (p = 0.23), nor does it increase the explained variance. INERPRETATION: Spontaneous births are well modelled by a time-dependent Poisson process when monthly and day-of-the-week variation is included. The frequency is highest in summer towards June and July, Friday and Tuesday stand out as particularly busy days, and the activity level is at its lowest during weekends.

Perspectives of Clinicians Involved in the RESTART-Study: Outcomes of a Focus Group.

PURPOSE: The purpose of this study was to explore the attitudes and beliefs of speech-language pathologists (SLPs) with regard to the Lidcombe Program and Demands and Capacities-based treatment and to examine how these attitudes and beliefs might have changed as a result of participating in the RESTART-study. METHOD: A focus group meeting with 13 SLPs was organized. The discussion was structured using questions on therapy preference, attitudes about and explicit comparison of both treatments and treatment manuals, and learnings of trial participation. RESULTS: Four main themes were identified. First, a change in attitude toward treatment choice was observed. Second, this change was related to a change in beliefs about the potential of both treatments. Third, aspects of the treatments regarded as success factors were considered. Last, learning outcomes and increased professionalism as a result of participating in the RESTART-trial were discussed. CONCLUSIONS: This study showed how attitudes and beliefs of SLPs with regard to the Lidcombe Program and Demands and Capacities-based treatment evolved during a randomized trial. This work increases our understanding of the role of attitudes and beliefs in the uptake and utilization of therapies and demonstrates the importance of collecting qualitative data. Results and recommendations should prove of value in implementing the RESTART-trial results and in training SLPs.

Fear of childbirth and elective caesarean section: a population-based study.

BACKGROUND: This population-based cohort study aimed to investigate the demographic and psychosocial characteristics associated with fear of childbirth and the relative importance of such fear as a predictor of elective caesarean section. METHODS: A sample of 1789 women from the Akershus Birth Cohort in Norway provided data collected by three self-administered questionnaires at 17 and 32 weeks of pregnancy and 8 weeks postpartum. Information about the participants' childbirths was obtained from the hospital records. RESULTS: Eight percent of the women reported fear of delivery, defined as a score of ≥85 on the Wijma Delivery Expectancy Questionnaire. Using multivariable logistic regression models, a previous negative overall birth experience exerted the strongest impact on fear of childbirth, followed by impaired mental health and poor social support. Fear of childbirth was strongly associated with a preference for elective caesarean section (aOR 4.6, 95% CI 2.9-7.3) whereas the association of fear with performance of caesarean delivery was weaker (aOR 2.4, 95% CI 1.2-4.9). The vast majority (87%) of women with fear of childbirth did not, however, receive a caesarean section. By contrast, a previous negative overall birth experience was highly predictive of elective caesarean section (aOR 8.1, 95% CI 3.9-16.7) and few women without such experiences did request caesarean section. CONCLUSIONS: Results suggest that women with fear of childbirth may have identifiable vulnerability characteristics, such as poor mental health and poor social support. Results also emphasize the need to focus on the subjective experience of the birth to prevent fear of childbirth and elective caesarean sections on maternal request. Regarding the relationship with social support, causality has to be interpreted cautiously, as social support was measured at 8 weeks postpartum only.