Neonatal morbidity and mortality in birth centers in the United States 2018-2021: An observational study of low-risk birthing individuals.

BACKGROUND: Many studies reporting neonatal outcomes in birth centers include births with risk factors not acceptable for birth center care using the evidence-based CABC criteria. Accurate comparisons of outcomes by birth setting for low-risk patients are needed. METHODS: Data from the public Natality Detailed File from 2018 to 2021 were used. Logistic regression, including adjusted and unadjusted odds ratios, compared neonatal outcomes (chorioamnionitis, Apgar scores, resuscitation, intensive care, seizures, and death) between centers and hospitals. Covariates included maternal diabetes, body mass index, age, parity, and demographic characteristics. RESULTS: The sample included 8,738,711 births (8,698,432 (99.53%) in hospitals and 40,279 (0.46%) in birth centers). There were no significant differences in neonatal deaths (aOR 1.037; 95% CI [0.515, 2.088]; p-value 0.918) or seizures (aOR 0.666; 95% CI [0.315, 1.411]; p-value 0.289). Measures of morbidity either not significantly different or less likely to occur in birth centers compared to hospitals included chorioamnionitis (aOR 0.032; 95% CI [0.020, 0.052]; p-value < 0.001), Apgar score < 4 (aOR 0.814, 95% CI [0.638, 1.039], p-value 0.099), Apgar score < 7 (aOR 1.075, 95% CI [0.979, 1.180], p-value 0.130), ventilation >6 h (aOR 0.349; [0.281,0.433], p-value < 0.001), and intensive care admission (aOR 0.356; 95% CI [0.328, 0.386], p-value < 0.001). Birth centers had higher odds of assisted neonatal ventilation for <6 h as compared to hospitals (aOR 1.373; 95% CI [1.293, 1.457], p-value < 0.001). CONCLUSION: Neonatal deaths and seizures were not significantly different between freestanding birth centers and hospitals. Chorioamnionitis, Apgar scores < 4, and intensive care admission were less likely to occur in birth centers.

The evolution of Ericaceae flowers and their pollination syndromes at a global scale.

PREMISE: Floral evolution in large clades is difficult to study not only because of the number of species involved, but also because they often are geographically widespread and include a diversity of outcrossing pollination systems. The cosmopolitan blueberry family (Ericaceae) is one such example, most notably pollinated by bees and multiple clades of nectarivorous birds. METHODS: We combined data on floral traits, pollination ecology, and geography with a comprehensive phylogeny to examine the structuring of floral diversity across pollination systems and continents. We focused on ornithophilous systems to test the hypothesis that some Old World Ericaceae were pollinated by now-extinct hummingbirds. RESULTS: Despite some support for floral differentiation at a continental scale, we found a large amount of variability within and among landmasses, due to both phylogenetic conservatism and parallel evolution. We found support for floral differentiation in anther and corolla traits across pollination systems, including among different ornithophilous systems. Corolla traits show inconclusive evidence that some Old World Ericaceae were pollinated by hummingbirds, while anther traits show stronger evidence. Some major shifts in floral traits are associated with changes in pollination system, but shifts within bee systems are likely also important. CONCLUSIONS: Studying the floral evolution of large, morphologically diverse, and widespread clades is feasible. We demonstrate that continent-specific radiations have led to widespread parallel evolution of floral morphology. We show that traits outside of the perianth may hold important clues to the ecological history of lineages.

Race, ethnicity, and indications for primary cesarean birth: Associations within a national birth center registry.

BACKGROUND: Racial and ethnic disparities in cesarean rates in the United States are well documented. This study investigated whether cesarean inequities persist in midwife-led birth center care, including for individuals with the lowest medical risk. METHODS: National registry records of 174,230 childbearing people enrolled in care in 115 midwifery-led birth center practices between 2007 and 2022 were analyzed for primary cesarean rates and indications by race and ethnicity. The lowest medical risk subsample (n = 70,521) was analyzed for independent drivers of cesarean birth. RESULTS: Primary cesarean rates among nulliparas (15.5%) and multiparas (5.7%) were low for all enrollees. Among nulliparas in the lowest-risk subsample, non-Latinx Black (aOR = 1.37; 95% CI, 1.15-1.63), Latinx (aOR = 1.51; 95% CI, 1.32-1.73), and Asian participants (aOR = 1.48; 95% CI, 1.19-1.85) remained at higher risk for primary cesarean than White participants. Among multiparas, only Black participants experienced a higher primary cesarean risk (aOR = 1.49; 95% CI, 1.02-2.18). Intrapartum transfers from birth centers were equivalent or lower for Black (14.0%, p = 0.345) and Latinx (12.7%, p < 0.001) enrollees. Black participants experienced a higher proportion of primary cesareans attributed to non-reassuring fetal status, regardless of risk factors. Place of admission was a stronger predictor of primary cesarean than race or ethnicity. CONCLUSIONS: Place of first admission in labor was the strongest predictor of cesarean. Racism as a chronic stressor and a determinant of clinical decision-making reduces choice in birth settings and may increase cesarean rates. Research on components of birth settings that drive inequitable outcomes is warranted.

The birth center model of care: Staffing, business characteristics, and core clinical outcomes.

OBJECTIVES: Interest in expanding access to the birth center model is growing. The purpose of this research is to describe birth center staffing models and business characteristics and explore relationships to perinatal outcomes. METHODS: This descriptive analysis includes a convenience sample of all 84 birth center sites that participated in the AABC Site Survey and AABC Perinatal Data Registry between 2012 and 2020. Selected independent variables include staffing model (CNM/CM or CPM/LM), legal entity status, birth volume/year, and hours of midwifery call/week. Perinatal outcomes include rates of induction of labor, cesarean birth, exclusive breastfeeding, birthweight in pounds, low APGAR scores, and neonatal intensive care admission. RESULTS: The birth center model of care is demonstrated to be safe and effective, across a variety of staffing and business models. Outcomes for both CNM/CM and CPM/LM models of care exceed national benchmarks for perinatal quality with low induction, cesarean, NICU admission, and high rates of breastfeeding. Within the sample of medically low-risk multiparas, variations in clinical outcomes were correlated with business characteristics of the birth center, specifically annual birth volume. Increased induction of labor and cesarean birth, with decreased success breastfeeding, were present within practices characterized as high volume (>200 births/year). The research demonstrates decreased access to the birth center model of care for Black and Hispanic populations. CONCLUSIONS FOR PRACTICE: Between 2012 and 2020, 84 birth centers across the United States engaged in 90,580 episodes of perinatal care. Continued policy development is necessary to provide risk-appropriate care for populations of healthy, medically low-risk consumers.

Outcomes of Cannabis Use During Pregnancy Within the American Association of Birth Centers Perinatal Data Registry 2007-2020: Opportunities Within Midwifery-Led Care.

BACKGROUND: Healthcare providers require data on associations between perinatal cannabis use and birth outcomes. METHODS: This observational secondary analysis come from the largest perinatal data registry in the United States related to the midwifery-led birth center model care (American Association of Birth Centers Perinatal Data Registry; N = 19 286). Births are planned across all birth settings (home, birth center, hospital); care is provided by midwives and physicians. RESULTS: Population data show that both early and persistent self-reports of cannabis use were associated with higher rates of preterm birth, low-birth-weight, lower 1-minute Apgar score, gestational weight gain, and postpartum hemorrhage. Once controlled for medical and social risk factors using logistic regression, differences for childbearing people disappeared except that the persistent use group was less likely to experience "no intrapartum complications" (adjusted odds ratio [aOR] = 0.49; 95% confidence interval [CI], 0.32-0.76; P < .01), more likely to experience an indeterminate fetal heart rate in labor (aOR = 3.218; 95% CI, 2.23-4.65; P < .05), chorioamnionitis (aOR = 2.8; 95% CI, 1.58-5.0; P < .01), low-birth-weight (aOR = 1.8; 95% CI, 1.08-3.05; P < .01), and neonatal intensive care unit (NICU) admission (aOR = 2.4; 95% CI, 1.30-4.69; P < .05). CONCLUSIONS: Well-controlled data demonstrate that self-reports of persistent cannabis use through the third trimester are associated with an increased risk of low-birth-weight and NICU admission.

Place of Birth Preferences and Relationship to Maternal and Newborn Outcomes Within the American Association of Birth Centers Perinatal Data Registry, 2007-2020.

PURPOSE: The purpose of this study was to describe sociodemographic variations in client preference for birthplace and relationships to perinatal health outcomes. METHODS: Descriptive data analysis (raw number, percentages, and means) showed that preference for birthplace varied across racial and ethnic categories as well as sociodemographic categories including educational status, body mass index, payer status, marital status, and gravidity. A subsample of medically low-risk childbearing people, qualified for birth center admission in labor, was analyzed to assess variations in maternal and newborn outcomes by site of first admission in labor. RESULTS: While overall clinical outcomes exceeded national benchmarks across all places of admission in the sample, disparities were noted including higher cesarean birth rates among Black and Hispanic people. This variation was larger within the population of people who preferred to be admitted to the hospital in labor in the absence of medical indication. CONCLUSION: This study supports that the birth center model provides safe delivery care across the intersections of US sociodemographics. Findings from this study highlight the importance of increased access and choice in place of birth for improving health equity, including decreasing cesarean birth and increasing breastfeeding initiation.

Progesterone and Preterm Birth: Using Empirical Research to Explore Structural Racism Within Midwifery-Led Care.

BACKGROUND: Progesterone has been the standard of practice for the prevention of preterm birth for decades. The drug received expedited Food and Drug Administration approval, prior to the robust demonstration of scientific efficacy. METHODS: Prospective research from the American Association of Birth Centers Perinatal Data Registry, 2007-2020. Two-tailed t tests, logistic regression, and propensity score matching were used. RESULTS: Midwifery-led care was underutilized by groups most at risk for preterm birth and was shown to be effective at maintaining low preterm birth rates. The model did not demonstrate reliable access to progesterone. People of color are most at risk of preterm birth, yet were least likely to receiving progesterone treatment. Progesterone was not demonstrated to be effective at decreasing preterm birth when comparing the childbearing people with a history of preterm birth who used the medication and those who did not within this sample. CONCLUSIONS: This study adds to the body of research that demonstrates midwifery-led care and low preterm birth rates. The ineffectiveness of progesterone in the prevention of preterm birth among people at risk was demonstrated.

Breastfeeding as a Quality Measure: Demonstrating Levers of the National Quality Strategy.

The purpose of this study is to explore the National Quality Strategy (NQS) levers (measurement and feedback, public reporting, learning and technical assistance, and certification) on state and national breastfeeding performance. The research evaluates the NQS levers of measurement and feedback and public reporting using secondary data analysis of publicly reported data from the National Immunization Survey and the Centers for Disease Control and Prevention Breastfeeding Report Cards between 2008 and 2018, the latest years available. Linear regression explores the association between the prevalence of state-level Baby-Friendly hospitals and state-level breastfeeding rates. Subsequent analyses use event study to test whether state-level Baby-Friendly hospital adoption is associated with higher breastfeeding rates. A 10% increase in Baby-Friendly hospitals at the state level is associated with increased population breastfeeding rates by nearly 5% and a decrease in early formula use (before 2 days of life) by 2% to 9%. Breastfeeding increased by 2% to 5% in the first 2 years following state-level Baby-Friendly initiatives, with subsequent increases up to 10% in the next 4 years. The National Quality Strategy levers of measurement and public reporting combined with certification and learning and technical assistance are associated with increases in exclusive breastfeeding, a national quality metric.

The American College of Nurse-Midwives' Benchmarking Project: A Demonstration of Professional Preservation and Improvement.

Maternal and newborn outcomes in the United States are suboptimal. Care provided by certified nurse-midwives and certified midwives is associated with improved health outcomes for mothers and newborns. Benchmarking is a process of continuous quality assurance providing opportunities for internal and external improvement. Continuous quality improvement is a professional standard and expectation for the profession of midwifery. The American College of Nurse-Midwives Benchmarking Project is an example of a long-standing, midwifery-led quality improvement program. The project demonstrates a program for midwifery practices to display and compare their midwifery processes and outcomes of care. Quality metrics in the project reflect national quality measures in maternal child health while intentionally showcasing the contributions of midwives. The origins of the project and the outcomes for data submitted for 2019 are described and compared with national rates. The American College of Nurse-Midwives Benchmarking Project provides participating midwifery practices with information for continuous improvement and documents the high quality of care provided by a sample of midwifery practices.

Subspecies differentiation in an enigmatic chaparral shrub species.

PREMISE: Delimiting biodiversity units is difficult in organisms in which differentiation is obscured by hybridization, plasticity, and other factors that blur phenotypic boundaries. Such work is more complicated when the focal units are subspecies, the definition of which has not been broadly explored in the era of modern genetic methods. Eastwood manzanita (Arctostaphylos glandulosa Eastw.) is a widely distributed and morphologically complex chaparral shrub species with much subspecific variation, which has proven challenging to categorize. Currently 10 subspecies are recognized, however, many of them are not geographically segregated, and morphological intermediates are common. Subspecies delimitation is of particular importance in this species because two of the subspecies are rare. The goal of this study was to apply an evolutionary definition of "subspecies" to characterize structure within Eastwood manzanita. METHODS: We used publicly available geospatial environmental data and reduced-representation genome sequencing to characterize environmental and genetic differentiation among subspecies. In addition, we tested whether subspecies could be differentiated by environmentally associated genetic variation. RESULTS: Our analyses do not show genetic differentiation among subspecies of Eastwood manzanita, with the exception of one of the two rare subspecies. In addition, our environmental analyses did not show ecological differentiation, though limitations of the analysis prevent strong conclusions. CONCLUSIONS: Genetic structure within Eastwood manzanita does not correspond to current subspecies circumscriptions, but rather reflects geographic distribution. Our study suggests that subspecies concepts need to be reconsidered in long-lived plant species, especially in the age of next-generation sequencing.

Rural resilience: The role of birth centers in the United States.

PURPOSE: To explore the role of the birth center model of care in rural health and maternity care delivery in the United States. METHODS: All childbearing families enrolled in care at an American Association of Birth Centers Perinatal Data RegistryTM user sites between 2012 and 2020 are included in this descriptive analysis. FINDINGS: Between 2012 and 2020, 88 574 childbearing families enrolled in care with 82 American Association of Birth Centers Perinatal Data RegistryTM user sites. Quality outcomes exceeded national benchmarks across all geographic regions in both rural and urban settings. A stable and predictable rate of transfer to a higher level of care was demonstrated across geographic regions, with over half of the population remaining appropriate for birth center level of care throughout the perinatal episode of care. Controlling for socio demographic and medical risk factors, outcomes were as favorable for clients in rural areas compared with urban and suburban communities. CONCLUSIONS: Rural populations cared for within the birth center model of care experienced high-quality outcomes. HEALTH POLICY IMPLICATIONS: A major focus of the United States maternity care reform should be the expansion of access to birth center models of care, especially in underserved areas such as rural communities.

Improving the Experience of Care: Results of the American Association of Birth Centers Strong Start Client Experience of Care Registry Pilot Program, 2015-2016.

In 2018, the Center for Medicare and Medicaid Innovation in the United States (US) released report demonstrating birth centers as the appropriate level of care for most Medicaid beneficiaries. A pilot project conducted at 34 American Association of Birth Centers (AABC) Strong Start sites included 553 beneficiaries between 2015 and 2016 to explore client perceptions of high impact components of care. Participants used the AABC client experience of care registry to report knowledge, values, and experiences of care. Data were linked to more than 300 process and outcome measures within the AABC Perinatal Data Registry™. Descriptive statistics, t tests, χ analysis, and analysis of variance were conducted. Participants demonstrated high engagement with care and trust in pregnancy, birth, and parenting. Beneficiaries achieved their preference for vaginal birth (89.9%) and breastfeeding at discharge through 6 weeks postpartum (91.7% and 87.6%). Beneficiaries reported having time for questions, felt listened to, spoken to in a way they understood, being involved in decision making, and treated with respect. There were no variations in experience of care, cesarean birth, or breastfeeding by race. Medicaid beneficiaries receiving prenatal care at AABC Strong Start sites demonstrated high levels of desired engagement and reported receiving respectful, accessible care and high-quality outcomes. More investment and research using client-reported data registries are warranted as the US works to improve the experience of perinatal care nationwide.

The Experience of Land and Water Birth Within the American Association of Birth Centers Perinatal Data Registry, 2012-2017.

Consumer demand for water birth has grown within an environment of professional controversy. Access to nonpharmacologic pain relief through water immersion is limited within hospital settings across the United States due to concerns over safety. The study is a secondary analysis of prospective observational Perinatal Data Registry (PDR) used by American Association of Birth Center members (AABC PDR). All births occurring between 2012 and 2017 in the community setting (home and birth center) were included in the analysis. Descriptive, correlational, and relative risk statistics were used to compare maternal and neonatal outcomes. Of 26 684 women, those giving birth in water had more favorable outcomes including fewer prolonged first- or second-stage labors, fetal heart rate abnormalities, shoulder dystocias, genital lacerations, episiotomies, hemorrhage, or postpartum transfers. Cord avulsion occurred rarely, but it was more common among water births. Newborns born in water were less likely to require transfer to a higher level of care, be admitted to a neonatal intensive care unit, or experience respiratory complication. Among childbearing women of low medical risk, personal preference should drive utilization of nonpharmacologic care practices including water birth. Both land and water births have similar good outcomes within the community setting.

Strong Start in birth centers: Socio-demographic characteristics, care processes, and outcomes for mothers and newborns.

BACKGROUND: A recent Center for Medicare and Medicaid Innovation report evaluated the four-year Strong Start for Mothers and Newborns Initiative, which sought to improve maternal and newborn outcomes through exploration of three enhanced, evidence-based care models. This paper reports the socio-demographic characteristics, care processes, and outcomes for mothers and newborns engaged in care with American Association of Birth Centers (AABC) sites. METHODS: The authors examined data for 6424 Medicaid or Children's Health Insurance Program (CHIP) beneficiaries in birth center care who gave birth between 2013 and 2017. Using data from the AABC Perinatal Data Registry™, descriptive statistics were used to evaluate socio-behavioral and medical risks, and core perinatal quality outcomes. Comparisons are made between outcomes in the AABC sample and national data during the study period. RESULTS: Childbearing mothers enrolled at AABC sites had diverse socio-behavioral risk factors similar to the national profile. The AABC sites exceeded national quality benchmarks for low birthweight (3.28%), preterm birth (4.42%), and primary cesarean birth (8.56%). Racial disparities in perinatal indicators were present within the Strong Start sample; however, they were at narrower margins than in national data. The enhanced model of care was notable for use of midwifery-led prenatal, labor, and birth care and decreased hospital admission. CONCLUSIONS: Birth center care improves population health, patient experience, and value. The model demonstrates the potential to decrease racial disparity and improve population health. Reduction of regulatory barriers and implementation of sustainable reimbursement are warranted to move the model to scale for Medicaid beneficiaries nationwide.

Not Missing the Opportunity: Improving Depression Screening and Follow-Up in a Multicultural Community.

BACKGROUND: Screening for depression and documenting follow-up is a National Quality Forum-endorsed measure. Yet only seven states report depression screening and follow-up, making it the fourth-least-reported measure on the Medicaid Adult Core Set. In 2016 a multicultural health center found that only 9.1% of clients were screened and followed up for depression. This quality improvement project was conducted to increase the efficacy of Screening, Brief Intervention, and Referral to Treatment (SBIRT) for depression to 75% for screen-positive clients. METHODS: Four Plan-Do-Study-Act (PDSA) cycles in a 90-day period focused on depression screening, patient engagement, population health management, and team building were used. The package of interventions-use of written standardized Patient Health Questionnaire (PHQ) screening tools in six languages, the Option Grid™ for clients with positive PHQ screens, a "right care" tracking log for those clients, and team meetings and in-services to support capacity building-were operationalized using a point-of-care notebook that created a physical reminder and trigger for the use of the intervention tools. Surveys, charts, and registry data were analyzed to evaluate the population health impact of the interventions. RESULTS: Provision of evidence-based care increased to 71.4%, and adherence to follow-up increased from 33.3% to 60.0%. Screening in the client's preferred language increased the rate to 85.2%, identifying a positive PHQ incidence of 45.5%. CONCLUSION: Rapid-cycle improvement with a population health focus demonstrated improved depression screening and follow-up within a multicultural community health center. Outcomes were attributed to team engagement and the use of standardized tools. These processes can be applied to other primary care settings.

Next-generation lineage discovery: A case study of tuberous Claytonia L.

PREMISE OF THE STUDY: Species formation is an intuitive endpoint of reproductive isolation, but circumscribing taxa that arise during speciation can be difficult because of gene flow, morphological continuity, hybridization or polyploidization, and low sequence variation among newly diverged lineages. Nonetheless, species complexes are ubiquitous, and their classification is essential for understanding how diversity influences ecosystem function. METHODS: We used modern sequencing technology to identify lineages of perennial Claytonia L. and assessed correspondence between genetic lineages and morphological/ecological variation. Subsets of 18 taxa from 63 populations were used for (a) lineage discovery using network and coalescent analyses, (b) leaf shape analyses using elliptical Fourier analysis and ordination, and (c) ecological analyses (soil chemistry, climate) using ANOVA and ordination. KEY RESULTS: Samples mainly aggregated into groups representing each of the previously recognized species in each of the genetic data sets. Compared to the double-digest restriction-site-associated DNA sequencing data set, genome skimming data provided more resolution and further opportunity to probe into patterns of nuclear and chloroplast genome diversity. Morphological and ecological associations are significantly different (albeit intergrading) among the taxa investigated. A new species, Claytonia crawfordii, is described based on morphological data presented here. CONCLUSIONS: Genetic data presented in this study provide some of the first insights into phylogenetic relationships among recently diverged perennial Claytonia and are suggestive of past hybridization among caudicose and tuberous species. Given prior difficulties in understanding species boundaries among newly diverged plant lineages, this case study demonstrates the revolutionary breakthrough for systematics research that high throughput sequencing represents.

Outcomes of childbearing Medicaid beneficiaries engaged in care at Strong Start birth center sites between 2012 and 2014.

BACKGROUND: Variations in care for pregnant women have been reported to affect pregnancy outcomes. METHODS: This study examined data for all 3136 Medicaid beneficiaries enrolled at American Association of Birth Centers (AABC) Center for Medicare and Medicaid Innovation Strong Start sites who gave birth between 2012 and 2014. Using the AABC Perinatal Data Registry, descriptive statistics were used to evaluate socio-behavioral and medical risks, and core perinatal quality outcomes. Next, the 2082 patients coded as low medical risk on admission in labor were analyzed for effective care and preference sensitive care variations. Finally, using binary logistic regression, the associations between selected care processes and cesarean delivery were explored. RESULTS: Medicaid beneficiaries enrolled at AABC sites had diverse socio-behavioral and medical risk profiles and exceeded quality benchmarks for induction, episiotomy, cesarean, and breastfeeding. Among medically low-risk women, the model demonstrated effective care variations including 82% attendance at prenatal education classes, 99% receiving midwifery-led prenatal care, and 84% with midwifery- attended birth. Patient preferences were adhered to with 83% of women achieving birth at their preferred site of birth, and 95% of women using their preferred infant feeding method. Elective hospitalization in labor was associated with a 4-times greater risk of cesarean birth among medically low-risk childbearing Medicaid beneficiaries. CONCLUSIONS: The birth center model demonstrates the capability to achieve the triple aims of improved population health, patient experience, and value.

Navigating the perinatal quality landscape.

The National Quality Strategy, mandated by the Affordable Care Act, outlines the triple aim of better health, better care, and lower costs. Perinatal nurses are integral to the National Quality movement as care providers, leaders, and experts. The most notable accomplishments in perinatal care of the last decade relate to the endorsement of quality measures by the National Quality Forum that provide unified goals and the quality improvement frameworks provided by the Institute for Healthcare Improvement that help systems create action and change through education, team building, process improvement, and structure. Fourteen perinatal quality measures are currently endorsed by the National Quality Forum, 5 of which are mandated by The Joint Commission and required for accreditation. Understanding the current perinatal quality measures and the resources available for implementation is essential to nursing care delivery. Realizing the nurses' role within the quality improvement landscape and mobilizing nationally endorsed quality measures as levers for nurse-led improvement projects promise actualization of marked quality improvement in perinatal care.

Multiple origins of circumboreal taxa in Pyrola (Ericaceae), a group with a Tertiary relict distribution.

BACKGROUND AND AIMS: In the Northern Hemisphere, Tertiary relict disjunctions involve older groups of warm affinity and wide disjunctions, whereas circumboreal distributions in Arctic-Alpine taxa tend to be younger. Arctic-Alpine species are occasionally derived from Tertiary relict groups, but Pyrola species, in particular, are exceptional and they might have occurred multiple times. The aim of this study was to reconstruct the biogeographic history of Pyrola based on a clear phylogenetic analysis and to explore how the genus attained its circumboreal distribution. METHODS: Estimates of divergence times and ancestral geographical distributions based on neutrally evolving DNA sequence variation were used to develop a spatio-temporal model of colonization patterns for Pyrola. KEY RESULTS: Pyrola originated and most diversification occurred in Asia; North America was reached first by series Scotophyllae in the late Miocene, then by sub-clades of series Pyrola and Ellipticae around the Pliocene. The three circumboreal taxa, P. minor, P. chlorantha and the P. rotundifolia complex, originated independently of one another, with the last two originating in Asia. CONCLUSIONS: Three circumboreal Pyrola lineages have arisen independently and at least two of these appear to have originated in Asia. The cool, high-altitude habitats of many Pyrola species and the fact that diversification in the genus coincided with global cooling from the late Miocene onwards fits a hypothesis of pre-adaptation to become circumboreal within this group.