Geographic and local drivers shape breastfeeding initiation across the U.S.

Nationwide county-level data underscore the need for locally tailored public health strategies

PLOS

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One key result from this paper, highlighted in this figure, reveals a spatially heterogeneous relationship between the percentage of female-headed households with children and breastfeeding initiation rates. Specifically, female-headed households are associated with stronger, more negative, and more localized effects on breastfeeding initiation. As a result, statistically significant negative associations were observed in some regions, including counties across the Upper Midwest, Mississippi Delta, Appalachia, and Eastern North Carolina. These patterns suggest that higher rates of female-headed households are linked to lower breastfeeding initiation rates in these areas. Further, the results underscore that this relationship operates at a localized spatial scale, reinforcing the importance of regional context when analyzing the influence of family structure on maternal and child health behaviors.

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Credit: Grubesic et al., 2026, PLOS Global Public Health, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

New data on breastfeeding initiation across the U.S. reveal broad geographic patterns as well as local factors that can inform targeted public health interventions. The study by Tony Grubesic from the University of California Riverside and colleagues was published July 15, 2026, in the open-access journal PLOS Global Public Health.

Breastfeeding is widely recognized as having important health benefits for both mothers and infants. National initiatives such as Healthy People 2030 aim to increase rates of breastfeeding initiation and persistence in the U.S.  One of the challenges toward this goal is that national statistics can mask geographic, demographic, economic, and cultural variability. At a county level, breastfeeding initiation rates varied from 22% to more than 90% in 2018-2019. Understanding this local variation is crucial to developing effective strategies to enhance breastfeeding education, community support, and, ultimately, breastfeeding initiation.

In this study, researchers analyzed county-level breastfeeding initiation data for infants born in 2018 and 2019, covering approximately 95.8% of U.S. counties. Using a multiscale geographically weighted regression (MGWR) model, they were able to gain a more accurate and nuanced understanding of breastfeeding patterns than traditional linear models, which can overlook local variation.

The study suggests that breastfeeding initiation is influenced by both broad national trends and highly localized factors. Consistent with previous studies, breastfeeding initiation rates were higher in the Northeast and along the West Coast, while lower rates were concentrated in Gulf Coast states and portions of Appalachia.

Several global trends were relatively sticky—education and race always matter regardless of geography. However, other trends were multifaceted. For example, while there was a strong positive association between breastfeeding initiation and Hispanic populations, this was primarily in the eastern U.S., not in the West or Southwest, where Hispanic populations are larger.

Overall, the study emphasizes that addressing disparities in breastfeeding initiation requires tailored, locally informed approaches in addition to national policy efforts. They also recommend 3 actionable, cost-effective strategies with a proven track record for improving breastfeeding initiation: more access to lactation consultants in hospitals; encouraging peer-to-peer breastfeeding support groups (like La Leche League); and expanding WIC eligibility and removing income restrictions for mothers seeking breastfeeding support.

The authors add: “By providing a comprehensive county-level analysis, this manuscript deepens our understanding of the structural and geographic barriers to breastfeeding initiation, which remains one of the most effective preventive health measures for reducing infant mortality and protecting mothers against chronic diseases. Furthermore, the study demonstrates that applying advanced spatial statistical modeling significantly outperforms traditional statistical methods, offering public health officials a precise, data-driven roadmap for deploying cost-effective community interventions where they are needed most."

  

In your coverage please use this URL to provide access to the freely available article in PLOS Global Public Health: https://plos.io/4ffuj1c 

Citation:  Grubesic TH, Kang W, Durbin KM, Helderop E (2026) Spatial inequalities in breastfeeding initiation in the United States: A multiscale analysis of county-level determinants. PLOS Glob Public Health 6(7): e0005659. https://doi.org/10.1371/journal.pgph.0005659  

Author Countries: New Zealand, United States

Funding: The authors received no specific funding for this work.

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Journal

PLOS Global Public Health

DOI

10.1371/journal.pgph.0005659 

Method of Research

Observational study

Subject of Research

People

Article Publication Date

15-Jul-2026

 

Large precolonial villages in the Brazilian Cerrado practiced maize-based polyculture

Max Planck Institute of Geoanthropology

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Eliane Chim selecting samples for stable isotope analysis

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Credit: Mariane Pereira Ferreira

For decades, researchers have debated the subsistence strategies of precolonial societies of the Brazilian Cerrado (tropical savanna): were they hunter-gatherers or intensive maize farmers, and in either case, how did they organize themselves and interact with the land they inhabited? This week, a study published in Science Advances provides the first large-scale direct evidence to answer these questions. The evidence shows that while some populations relied on diverse plants, maize farming played a central role for others. But rather than practicing intensive monoculture, these communities developed diversified maize-based polyculture systems.

“For many years, the Cerrado debate focused on two extremes: highly mobile foraging or intensive sedentary farming,” says Eliane Chim, lead author of the study. “Instead, we found that some societies depended heavily on maize grown within diversified agricultural systems capable of sustaining large villages. This fundamentally changes our understanding of Indigenous food production and settlement in central Brazil.”

The researchers analyzed stable carbon, nitrogen, and oxygen isotopes from the teeth and bones of more than 100 individuals recovered from 37 archaeological sites across the Cerrado, Caatinga and Atlantic Forest biomes. Combined with new radiocarbon dates from human bone collagen, faunal isotope baselines, archaeobotanical evidence and palaeoecological records, the study reconstructs diets across the region during the Late Holocene with chronological precision.

The isotope evidence shows that people associated with the open-air villages obtained a substantial proportion of their diet from maize, whereas contemporaneous populations living in nearby rock shelters consumed much more diverse foods and showed little evidence of intensive maize use. Because these groups occupied similar environments, the differences cannot be explained by ecology alone. Instead, they reveal the coexistence of distinct cultural traditions and economic strategies across the region.

“These results challenge broader ideas about how agriculture developed in tropical South America,” says Prof. Patrick Roberts, director of the Department of Coevolution of Land Use and Urbanisation at the Max Planck Institute of Geoanthropology. “Our findings show that maize was part of resilient polycultural food-production systems that combined domesticated crops with wild plants and local ecological knowledge.”

The findings also place the Cerrado alongside the Amazon as a major centre for understanding Indigenous innovation before European colonization.

“The Cerrado has often been overshadowed by the Amazon in discussions of precolonial land use,” says Prof. André Strauss of the Museum of Archaeology and Ethnology at the University of São Paulo (Brazil). “Our findings demonstrate that it was also a centre of innovation, where different societies developed distinct ways of interacting with one of the world's most biodiverse tropical landscapes.”

Beyond archaeology, the research contributes to understanding the long history of human influence on one of the world's richest tropical savannas, highlighting sustainable land-use strategies that helped shape Cerrado landscapes for centuries. These findings contribute not only to refining our understanding of past food production but also contribute to contemporary discussions on biodiversity conservation, Indigenous knowledge, and the long-term management of tropical ecosystems.

Aratu funerary urn with its lid, referred to in Portuguese as an ‘opérculo.’ Excavation at Vale Verde site, Bahia Brazil

Credit

Luydy Fernandes

 

Aratu funerary urn. Museu de Arqueologia e Etnologia, Universidade de São Paulo

Credit

Mauricio de Paiva

Journal

Science Advances

DOI

10.1126/sciadv.aef7066 

Article Title

Maize-based polyculture, not monoculture, sustained pre-colonial societies in the Brazilian Cerrado

Article Publication Date

15-Jul-2026

 

Evolution gives marsupials a helping hand

Scientists have discovered marsupial forelimbs (arms) develop before birth much earlier than previously thought, providing new insights into evolutionary innovation and biology

University of Melbourne

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​Progression of limb development in a dunnart embryo over three days

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Credit: Dr Axel Newton

Scientists have discovered marsupial forelimbs (arms) develop before birth much earlier than previously thought, providing new insights into evolutionary innovation and biology.  

Forelimbs are critical for survival in marsupials; newborns are typically very small and underdeveloped but rely on strong, fully formed arms to crawl unaided to the teat immediately after birth. 

University of Melbourne lead author Dr Axel Newton from the School of BioSciences said the research, published today in Science Advances,highlights the truly remarkable biology of marsupials. 

“Many of Australia’s iconic wildlife are marsupials, including kangaroos, koalas, wombats, and the Tasmanian devil, and we need to understand their evolutionary quirks to better protect them,” Dr Newton said. 

“We found that marsupial forelimbs rapidly develop over a four-day period, going from a flat featureless bud to fully functional arms with claws, which completely challenges our current understanding of limb development in vertebrates.  

“The early forelimbs appear before many major structures are formed, including somites and the neural tube, which are essentially the building blocks of the body.”  

In partnership with Professor Karen Sears at the University of California, Los Angeles (UCLA), the researchers studied two distantly related marsupials, the fat-tailed dunnart (Sminthopsis Crassicaudata) and the gray short-tailed opossum (Monodelphis domestica) to examine the distribution of genes following fertilisation.  

The research challenges previously held assumptions on the biological process of limb growth. Rather than following a single fixed sequence, key events in embryonic development seen in other species are bypassed or reorganised in marsupials. 

“Our previous understanding on how forelimbs grow has largely come from chicken or mice models, where many tissues grow at the same time. The development of marsupial limbs in isolation from other tissues provides an excellent model to untangle how limbs first form,” Dr Newton explained. 

“This not only reveals unexpected flexibility in limb development, but also paves the way for better understanding of how congenital human limb defects may arise.”  

The research was undertaken at the University of Melbourne’s Pask Lab in partnership with Colossal Biosciences.  

Professor Andrew Pask, head of the Pask Lab, said the research is important in our broader conservation efforts.  

“Understanding how evolution has shaped the development of our extraordinary marsupial mammals is fundamental to conserving them,” Professor Pask said. 

“If we don't understand the biology of how these animals are built, we can't fully understand their vulnerabilities, their resilience, or how to intervene when a species is in trouble. This research is a great example of how developmental biology feeds directly into the conservation science we do every day."  

Newborn dunnarts crawling to their mother's pouch [VIDEO] 

A group of dunnarts

Credit

Dr Emily Scicluna

Journal

Science Advances

DOI

10.1126/sciadv.aed3192 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Heterochronic limb patterning in marsupials reveals flexibility in the processes underlying lateral plate mesoderm morphogenesis

Article Publication Date

15-Jul-2026

 

Air from Greenland snow shows industrialization's impact on atmospheric methane

Reconstruction based on clumped isotopes

Utrecht University, Faculty of Science

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Researchers obtained up to 40-year-old air from compacted snow, called firn, on Greenland

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Credit: Thomas Röckmann

[Lead]

An international team of researchers, including scientists from Utrecht University and the University of Maryland, has reconstructed the concentration of clumped isotopes of methane in air from the past for the first time. This provides new insights into how atmospheric methane concentrations have changed since the start of the industrial era, around 1850. For the study, the scientists used air roughly forty years old, preserved in compacted snow (firn) in Greenland. The results were published in Science Advances.

 

[Intro]

Methane is the second most important greenhouse gas after CO2, responsible for around thirty percent of global warming to date. Atmospheric methane concentrations are rising, but it is not yet fully understood why that happens.

 

Human fingerprint

The researchers' measurements and analyses showed that the concentration of clumped methane isotopes, rare methane molecules with two heavy atoms clustered together, has changed significantly over the past decades. At first, the researchers couldn't fully explain this shift, but after running model simulations of the atmosphere spanning the last thousand years, they were able to pinpoint a cause. "Since the start of industrialisation, humans have disrupted the balance between methane emissions and breakdown so profoundly that it's visible in our measurements," explains Malavika Sivan, first author of the study.

 

Malavika Sivan, former researcher at IMAU and first author of the study: “Since the start of industrialisation, humans have disrupted the balance between methane emissions and breakdown so much that it's visible in our measurements.”

 

Methane balance

The clumped isotope signal reflects the balance between how much methane is emitted and how much is removed from the atmosphere. That balance determines whether atmospheric methane concentrations keep rising or start to fall. With this information, researchers can reconstruct the methane balance over time, and going forward, allowing them to check whether measures taken to reduce methane emissions are working.

That matters, says Thomas Röckmann, professor of Atmospheric Physics and Chemistry. "Reducing methane concentrations is one of the fastest ways to slow global warming in the short term." Continued human emissions and possible climate feedback from natural sources could drive further increases. "Policy initiatives like the Global Methane Pledge, which aims for a thirty percent cut in methane emissions by 2030 compared to 2020, might help slow or reverse that trend," Röckmann explains.

 

Thomas Röckmann, professor of Atmospheric Physics and Chemistry: “Reducing methane concentrations is one of the fastest ways to slow global warming in the short term.”

 

A surprising measurement

The research was prompted by an unexpected finding: the researchers measured clumped methane isotopes in the current atmosphere. The occurrence of these molecules was far higher than in methane from known sources such as wetlands, agriculture, and fossil fuels. Those sources couldn't account for such a strong signal.

The team concluded that the clumped isotope signal must originate from methane removal: when methane breaks down in the atmosphere through reactions with other substances. These clumped molecules react slower than normal methane molecules. “Following this, we wondered if we could use these clumped methane signatures to learn how the removal reactions changed in the atmosphere over time”, Röckmann explains.

 

Forty-year-old air

Methane is mainly released from biological and fossil sources. It forms naturally in wetlands, rice paddies, landfills, and agricultural systems, and is also released from fossil fuels such as coal, oil, and natural gas. To understand how methane sources and removal have changed over time, the researchers needed access to air from the past. And not just a little: analysing clumped methane isotopes requires as much as a thousand liters of air.

That old air can be found in firn: a layer of dense snow between the surface and the underlying glacial ice, where air remains trapped that is sometimes up to seventy years old. At the EastGRIP research station in Greenland, Röckmann collected the necessary air samples by drilling deep into the snow and essentially pumping the air out with specialised equipment. “We collected 500 to 700 litre air samples that were up to forty years old,” Röckmann says. “Analysing that air tells you a lot about the composition of the atmosphere in the past.”

 

An international collaboration

The amount of air was still on the low end for reaching the best precision with the instrument that is used in Utrecht. But a research group at the University of Maryland had a different instrument that could do the same measurements using less air. Sivan travelled to the University of Maryland for two months to analyse the air samples, together with her colleague Jiayang Sun. "There was a lot of trial and error, but in the end, we were excited to see such a strong temporal change in the clumped isotope signal.”

The results were unexpected, and it took a lot of discussion and modelling to understand the signal measured. “But it was worth it: we really understand how the clumped isotope signal records the influence of humans on the atmosphere in the industrial period" Sivan says.

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Journal

Science Advances

DOI

10.1126/sciadv.aeb2203 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Anthropogenic perturbations to atmospheric methane reflected in Greenland firn air clumped isotope measurements

Article Publication Date

15-Jul-2026

 

Researchers obtained up to 40-year-old air from compacted snow, called firn, on Greenland

Researchers obtained up to 40-year-old air from compacted snow, called firn, on Greenland. In this image you see Thomas Röckmann holding two barrels of compressed air.

Credit

Thomas Röckmann

The air was analysed by Malavika Sivan and Jaiyang Sun in a lab at the University of Maryland.

 

Malavika Sivan working on the analysis of the obtained air at the University of Maryland.

Credit

Malavika Sivan