16
May
Pesticide Exposure-Induced Gestational Anemia Mitigated by Maternal Gut Microbiota
(Beyond Pesticides, May 16, 2025) A Chinese study reports for the first time an association between gestational anemia (GA), pesticide exposure, and the potentially protective effects of gut microbes. While the report is a preprint and has not yet been peer reviewed, it establishes important connections eminently worthy of deeper investigation and suggests that the balance of gut microbes may be a highly effective way to reduce or prevent GA.
This is a prospective study of women enrolled in 2017 and 2018 in the Mother and Child Microbiome Cohort, ongoing at a Nanjing hospital. The 731 women were over 18, without diabetes or gestational hypertension (which can affect gestational anemia). The researchers collected blood samples to analyze red blood cell count (RBC), hemoglobin (Hb), and levels of pesticides. They analyzed stool samples for gut bacteria composition.
GA is extremely common. Pregnancy increases maternal blood volume by up to 50 percent, which produces obvious challenges to the mother. There is a strong gradient between the developing and developed countries: According to the World Health Organization, 35.5 percent of pregnant women globally had anemia in 2023. In Mali, 62.1 percent suffered from it. In the United States, about ten percent did. The current study cites a figure of 19.8 percent among pregnant Chinese women. Effects range from fatigue and shortness of breath in mothers to preterm birth, low birth weight, and cognitive and behavioral problems in children. The direct cause is considered to be iron, folate and vitamin B12 deficiencies, which are treated with nutritional supplementation, but the authors of the current study point out that there are many factors contributing to the problem, and these may be deeply rooted in molecular processes related to the formation of blood cells, or hematopoiesis, in bone and bone marrow.
While there is little research directly focused on GA and pesticide exposure, there is plenty of evidence that pesticides interfere with hematopoiesis (blood cell production). Beyond Pesticides has covered research showing an association between pesticides and iron deficiency, pernicious and aplastic anemias in female Indonesian farmworkers. There is a strong link between glyphosate and the blood disease non-Hodgkin lymphoma. In February, Beyond Pesticides reviewed a hypothesis advanced by Charles Benbrook, PhD, discussing the storage of glyphosate in bone. Dr. Benbrook proposes that glyphosate damages the DNA of hematopoietic stem cells, inducing oxidative stress. This could trigger the development of blood cancers.
How this body of hematologic evidence relates to GA is not clear. But in the current study, the researchers found “robust associations†between pesticides, risk of GA, and reduced levels of RBC and Hb. Among the associated pesticides were atrazine and clomazone, both herbicides, and pyrimethanil, a fungicide. This study reports the first human epidemiologic evidence of atrazine’s role in GA, adding to suggestive evidence from animal studies. Atrazine was linked to GA onset and reduced RBC and Hb levels.
Atrazine is currently under review by the U.S. Environmental Protection Agency (EPA), whose 2019 proposed registration review decision contains only a passing mention of human health effects based on atrazine’s endocrine-disrupting effects and therefore no information whatsoever about any association with blood disorders. The main focus of the review, which Beyond Pesticides has critiqued in detail, is to raise the concentration-equivalent level of concern (CE-LOC) affecting aquatic organisms. Beyond Pesticides has also exposed numerous other threats to reproductive health and incoherent policies regarding atrazine, such as its link to breast cancer here. The potential connections between pesticides’ effects on blood disorders and their effects on reproductive hormones should be urgently investigated, particularly in the case of pregnant women, whose bodies undergo such significant and rapid changes.
There is some good news in the current study in the form of microbial mitigation. “Notably, we identified for the first time that the effects of pesticides on GA may be mediated by gut microbiota,†the researchers wrote. Gut microbes are known to regulate iron metabolism through their production of short-chain fatty acids, which enhance the solubility and absorption of intestinal iron. Conversely, disruptions in gut microbiota trigger inflammation, which then damages several processes involved in producing and maintaining the balance of red blood cells in bone marrow
Earlier studies have established that pesticides reduce microbial diversity and interfere with microbes’ functioning. For example, the current authors note, the insecticide chlorpyrifos reduces populations of beneficial lactobacilli and bifidobacteria, which are involved in folate synthesis. They found that, indeed, pesticide exposure altered the community structure of the women’s gut microbes. There were differences in relative species abundance between women with and without GA. Women with GA had higher levels of some microbes that damage the gut lining and trigger inflammation.
One particular genus found in higher abundance in the non-GA group, Roseburia, may be especially helpful. Roseburia intestinalis has already been linked to the improvement or prevention of inflammatory bowel disease, alcoholic fatty liver disease, colorectal cancer, and atherosclerosis. “Regulating gut microbiota diversity and enhancing oral intake of Roseburia may help mitigate the GA-inducing effects of pesticide residues, potentially improving both maternal and offspring health,†the authors write. There is, however, not yet a probiotic supplement for increasing intestinal Roseburia levels, and the best way to encourage the microbes is a Mediterranean diet.
The authors emphasize that “[O]ur results added to the mounting evidence that gut microbiota serve as mediating factors between environmental stressors and maternal health.†One very obvious way to increase maternal health is to reduce a major stressor by switching to organic agriculture at the earliest opportunity.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Sources:
Pesticide exposure induces risks of gestational anemia by maternal gut microbiota: A prospective cohort study
Dong et al
Journal of Hazardous Materials
Preprint April 2025
https://www.sciencedirect.com/science/article/abs/pii/S0304389425013809
Glyphosate Weed Killer Contaminates Stem Cells, Is Linked to Blood Cancers and DNA Damage, Study Finds
Beyond Pesticides, February 27, 2025
https://beyondpesticides.org/dailynewsblog/2025/02/glyphosate-weed-killer-contaminates-stem-cells-is-linked-to-blood-cancers-and-dna-damage-study-finds/
Hypothesis: glyphosate-based herbicides can increase risk of hematopoietic malignancies through extended persistence in bone
Charles Benbrook
Environmental Sciences Europe 2025
https://enveurope.springeropen.com/articles/10.1186/s12302-025-01057-1
Assessment of the safety and probiotic properties of Roseburia intestinalis: A potential “Next Generation Probiotic”
Zhang et al
Frontiers of Microbiology 2022
https://pubmed.ncbi.nlm.nih.gov/36160246/
