{"id":40429,"date":"2025-12-02T00:01:36","date_gmt":"2025-12-02T05:01:36","guid":{"rendered":"https:\/\/beyondpesticides.org\/dailynewsblog\/?p=40429"},"modified":"2025-12-01T15:16:51","modified_gmt":"2025-12-01T20:16:51","slug":"research-finds-maternal-pesticide-exposure-impacts-reproductive-hormones-in-infant-girls","status":"publish","type":"post","link":"https:\/\/beyondpesticides.org\/dailynewsblog\/2025\/12\/research-finds-maternal-pesticide-exposure-impacts-reproductive-hormones-in-infant-girls\/","title":{"rendered":"Research Finds Maternal Pesticide Exposure Impacts Reproductive Hormones in Infant Girls"},"content":{"rendered":"

(Beyond Pesticides<\/em>, December 2, 2025) Recently published in Reproductive Toxicology<\/em><\/a>, researchers in Denmark and Iceland investigate the impacts of pesticides on sex hormones, finding that \u201cprenatal exposure to [the insecticide] chlorpyrifos<\/a> and [weed killer] 2,4-D<\/a> may affect the reproductive<\/a> hormones in girls, but not boys, during minipuberty, which may have long-term implications.\u201d Based on their analysis of urinary maternal concentrations of the pesticides and their metabolites and hormone levels in infants, the authors report, \u201cThis study examined the association between maternal pesticide exposure and pituitary, gonadal, and adrenal hormones in offspring during infancy.\u201d The sex-specific findings highlight a public health concern with potentially long-lasting transgenerational effects.<\/p>\n

\u201cWe recruited pregnant women from 2010 to 2012 in the Odense Child Cohort, including 489 mother-child pairs,\u201d the authors state. They continue: \u201cMaternal urinary concentrations of the generic pyrethroid<\/a> metabolite 3-phenoxybenzoic acid (3-PBA), the chlorpyrifos metabolite<\/a> 3,5,6-trichloro-2-pyridinol (TCPY), and the herbicide 2,4-D were measured at gestational week 28. Serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T), estrone (E1), estradiol (E2), 17-hydroxyprogesterone (17-OHP), Androstenedione (Adione), and Dehydroepiandrosterone sulfate (DHEAS) were assessed in infancy.\u201d<\/p>\n

The results of the analyses show that in girls, higher maternal urinary TCPY and 2,4-D concentrations are significantly associated with LH levels, which are hormones produced by the pituitary gland that trigger ovulation and regulate the menstrual cycle. Additional associations, specific to girls, between maternal levels of 3-PBA, TCPY, and 2,4-D and lower LH, FSH, E1, and E2 are also noted. The strongest associations are noted with the chlorpyrifos metabolite (TCPY) and 2,4-D, while the metabolite of many pyrethroids (3-PBA<\/a>) shows slightly weaker results. No associations are seen in boys within this study.<\/p>\n

\u201cOur findings suggest that, even in this low-exposed cohort, prenatal exposure to the insecticide metabolite TCPY and the herbicide 2,4-D causes persisting alterations of the HPG axis [hypothalamic-pituitary-gonadal axis that controls reproduction] in healthy infant girls,\u201d the researchers say. \u201cThis raises public health concerns, as all participants were exposed to TCPY and 2,4-D, the latter of which remains widely used.\u201d<\/p>\n

Background<\/strong><\/p>\n

Chlorpyrifos<\/a>, an organophosphate insecticide, was widely used in the European Union prior to the 2020 ban, which stemmed from concerns<\/a> about developmental neurotoxicity and carcinogenicity. The persistence of chlorpyrifos, however, leads to detection years after use in the environment. 2,4-dichlorophenoxyacetic acid<\/a> (2,4-D), phenoxyacetic acid herbicide, remains widely used to control broadleaf weeds. Both of these pesticides are registered by the U.S. Environmental Protection Agency (EPA) for use in crop production and on golf courses. However, there are certain state-level restrictions, such as in Hawaii<\/a>, Maryland, Washington<\/a>, Oregon, and California<\/a>.<\/p>\n

\u201cIn the general population, pesticide exposure primarily occurs through diet, particularly via residues in cereals, fruits, and vegetables,\u201d the authors state. They continue: \u201cInsecticides are rapidly metabolised and primarily excreted in urine within 24\u00a0h, whereas 2,4-D is largely excreted unmetabolized, making urinary biomarkers effective for monitoring exposure to both compound classes.\u201d<\/p>\n

Comparing maternal urinary concentrations of pesticides to impacts on infants highlights cascading implications to future generations. As the researchers describe: \u201cShortly after birth, the hypothalamic-pituitary-gonadal (HPG) hormone axis is transiently activated, resulting in increasing blood concentrations of gonadotropins and sex hormones well within the reference range for adults. This brief hormone peak during the first six months after birth is referred to as minipuberty, after which reproductive hormone levels remain low until puberty. Minipuberty allows for the maturation of sexual organs and could serve as a window of opportunity for reproductive function during adulthood and may be a sensitive marker of affected early gonadal development<\/a> during the male programming window.\u201d<\/p>\n

Beyond Pesticides has a long history<\/a> of covering the impacts on infants and children from pesticide exposure. Children face much higher hazards than adults from pesticide exposure. Their small size and developing organ systems, propensity to crawl and play near the ground, tendency for frequent hand-to-mouth motion, and greater intake of air and food relative to body weight make them particularly susceptible. Many of these risks start before a child is born, indicating the need for pregnant mothers to take particular care to avoid contact with hazardous pesticides.<\/p>\n

Study Methodology and Results<\/strong><\/p>\n

The 489 mother-child pairs, with 45% of the infants as female, included in the study are derived from the Odense Child Cohort<\/a> (OCC), a longitudinal Danish birth cohort including women pregnant between 2010 and 2012. From the mothers, fasting spot urine samples were collected in gestational week 28. \u201cThe urine samples were analysed for 3-PBA (a common metabolite of most pyrethroids and therefore a biomarker for the combined exposure to mixtures of pyrethroids), TCPY (a metabolite of both the organophosphate chlorpyrifos and the sister-compound chlorpyrifos-methyl), and 2,4-D (an herbicide),\u201d the authors explain.<\/p>\n

Serum samples of reproductive hormones were obtained from the infants at a mean age of 3.8 months. \u201cWe used multivariate linear regression analysis to investigate associations between maternal urinary concentrations of pesticide biomarkers and hormone standard deviations during minipuberty in the offspring, stratified by sex,\u201d the researchers state.<\/p>\n

As a result, most maternal urine samples show detectable concentrations of 3-PBA (93%), TCPY (91%), and 2,4-D (97%), and the analyses reveal that the concentrations of pesticide metabolites are inversely associated with circulating levels of reproductive hormones in girls. \u201cGenerally, there was a trend towards lower hormone levels (i.e., LH, FSH, E1, and E2) with increasing maternal urinary concentrations of 3-PBA, TCPY, and 2,4-D in girls,\u201d the authors report. \u201cConcerning boys, there were no associations between maternal concentrations of 3-PBA, TCPY, and 2,4-D and reproductive hormones… Our findings suggest that prenatal pesticide exposure may affect pituitary and\/or hypothalamic function in infant girls, potentially altering normal endocrine activity.\u201d<\/p>\n

Previous Research<\/strong><\/p>\n

A wide of science exists connecting chlorpyrifos and 2,4-D, among many other pesticide active ingredients, to deleterious health implications, labeling them \u201cas potential endocrine disruptors capable of interfering with sex hormone activity in vitro, primarily by affecting androgen function.\u201d (See here<\/a>, here<\/a>, and here<\/a>.) The researchers continue: \u201cThus, these compounds may pose risks during early development. Fetal exposure may interfere with fundamental epigenetic modifications<\/a>, potentially impairing organ development.\u201d<\/p>\n

To the authors\u2019 knowledge, only one previous study<\/a> in humans examines the potential effects of pesticide exposure during pregnancy on reproductive hormones during minipuberty, but only includes boys. \u201cThey found trends towards reduced testosterone (T) levels and increased ratio of luteinizing hormone (LH) to T in exposed boys, and also increased follicle stimulating hormone (FSH), suggesting impaired testicular function and compensated increase of gonadotropin levels, in 113 sons of women working in greenhouses in Denmark,\u201d the researchers summarize.<\/p>\n

Additional experimental studies are consistent with the findings in the current study:<\/p>\n