Importance:Cardiovascular disease (CVD) is the leading cause of death among women worldwide. Pregnancy serves as a natural cardiovascular stress test and universal clinical encounter, yet few approaches leverage its insights to inform long-term cardiovascular risk. Objective:To determine whether clinical measures and biomarkers obtained during pregnancy may identify women at risk of long-term CVD. Design, Setting, and Participants:This was a registry-linked, population-based cohort study of all pregnancies reaching at least 22 weeks between June 2010 and October 2013 in Southern Denmark. Primary analyses were performed in a nested prospective subcohort of Odense Child Cohort participants with available pregnancy biomarker data. Women with preexisting CVD were excluded (n = 114). Follow-up was done through December 31, 2023. Among 38 455 eligible women, 2056 had biomarker data at week 12 or week 29. Analytic subsets with complete data were used for prognostic modeling at week 12 (n = 1379) and week 29 (n = 1389). Exposures:Clinical characteristics, obstetric outcomes, and pregnancy biomarkers including soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor, high-sensitivity cardiac troponin I (hs-cTnI), and N-terminal pro-B-type natriuretic peptide. Main Outcomes and Measures:Incident maternal CVD, evaluated using Cox proportional hazards models. Results:In the biomarker cohort (median [IQR] age, 30.4 [27.4-33.8] years), 28 women (1.4%) developed CVD during a median (IQR) follow-up of 11.9 (11.2-12.5) years. Maternal age, hypertensive disorders of pregnancy (HDPs), and third-trimester concentrations of hs-cTnI and sFlt-1 were each independently associated with higher long-term CVD risk. A combined model including age and sFlt-1 measured at week 29 improved discrimination for CVD compared with a base model of age alone (ΔAUC, 0.16; 95% CI, 0.02-0.30), whereas a clinical model consisting of age, systolic blood pressure, and non-high-density lipoprotein cholesterol did not. Results were consistent in women without prior hypertension or HDPs and in nulliparous women. CVD incidence and the predictive value of the base model were comparable between the biomarker and the contemporaneous background cohorts (n = 36 274). Conclusions and Relevance:These findings support pregnancy as an opportunistic window for sex-specific cardiovascular risk assessment and prevention throughout a woman's life course. Further studies are warranted to validate these findings.

Prenatal exposure to paracetamol (also known as acetaminophen; N-acetyl-para-aminophenol; APAP) has been implicated in the disruption of sexual differentiation of the brain during neurodevelopment, potentially leading to altered sexual behaviour. This study aimed to evaluate the long-term effects of prenatal APAP exposure on sexually dimorphic behaviour in adult mice. Pregnant C57BL/6 dams were administered 150 mg/kg/day of APAP or tap water from 7 days post-coitum until birth. Behavioural assays, anogenital distance measurements, and steroidal and morphological analyses of gonads were performed on adult offspring at 16-17 weeks postnatally. Prenatal APAP exposure resulted in reduced anogenital distance and alterations in sexually dimorphic behaviour in adult mice, indicating that APAP disrupted both urogenital and brain sexual development. As expected, significant sex differences in spontaneous behaviour were observed in vehicle-treated mice. These differences were absent in APAP-exposed mice, suggesting that the sexes had become more similar in their behavioural patterns. Furthermore, APAP exposure influenced gonadal steroidogenesis, as evidenced by decreased testicular corticosteroid 11-deoxycortisol in males and decreased ovarian 17OH-progesterone and androstenedione levels in females. These findings demonstrate that prenatal APAP exposure disrupts sexually dimorphic neurodevelopment with persistent effects in adults, underscoring the necessity for further research on the implications of APAP use during pregnancy.

BackgroundPerfluoroalkyl substances (PFAS) are endocrine disrupting chemicals with abilities to interfere with aldosterone synthesis. Aldosterone is an essential steroid hormone and independent determinant of placental weight and birth weight.ObjectiveTo investigate associations of PFAS exposure with 24hour urine and plasma aldosterone in pregnant women.MethodsUsing data from Odense Child Cohort, we investigated associations between serum concentrations of five PFAS - perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) - with 24h urine (U-) and plasma (P-) aldosterone during pregnancy using multiple linear regression models.ResultsA doubling in PFOS, PFOA, and PFNA at median gestational week (GW) 12 (25th, 75th percentile: 10, 15) associated with a change in U-aldosterone concentrations at median GW 29 (25th, 75th percentile: 28, 29) by -4.8% (95% CI: -8.4%, -1.0%), -5.9% (95% CI: -9.1%, -2.7%), and -6.2% (95% CI: -9.9%, -2.4%), respectively. Compared to the first tertile, exposure to PFOS and PFOA in third tertile, and PFNA in second and third tertile associated with lower concentrations of U-aldosterone. A dose-response relationship was observed across tertiles for PFOS, PFOA, and PFNA with U-aldosterone. No significant association was demonstrated between PFAS exposure and P-aldosterone at median GW 29 (25th, 75th percentile: 28, 29).ConclusionHigher exposure concentrations of PFOS, PFOA, and PFNA in 1st trimester were associated with lower concentrations of 24h U-aldosterone in 3rd trimester. This inverse association may be a possible mechanistic link adding to PFAS-aldosterone-associated lower placental weight and birth weight.

BACKGROUND:Paracetamol is the most used medication during pregnancy, and concerns have been raised regarding potential associations with child neurodevelopment. OBJECTIVE:To investigate whether maternal paracetamol use during pregnancy, assessed by self-reports and urinary concentrations, was associated with intelligence quotient (IQ) in children aged 7. METHODS:The study used data from the Odense Child Cohort, Denmark, including 2448 pregnant women enrolled between 2010 and 2012. The women completed three questionnaires on paracetamol use during pregnancy; a subgroup of 518 had urinary paracetamol concentrations measured at gestational week 28. Concentrations >4000 ng/mL indicated use within the past 48 h, whereas >2000 ng/mL reflected earlier use. Child IQ was evaluated using four subscales from the Wechsler Intelligence Scale for Children - Fifth Edition. Propensity score-weighted regression models estimated differences in IQ points between users and non-users. RESULTS:A total of 1162 mother-child pairs were included; 65% (N = 777) reported paracetamol use during pregnancy. Self-reported use was non-significantly associated with a reduction of 1.3 IQ points (95% CI -3.0, +0.3). Paracetamol was detected in all urine samples, with 6% indicating recent use. Children of mothers with high urinary concentrations >4000 ng/mL, indicating recent use, showed a non-significant reduction of 1.6 IQ points (-5.9, +2.7). Similar results for concentrations >2000 ng/mL. Analyses excluding women with infections or other indications were compatible with main findings. CONCLUSION:These results suggest a potential association between paracetamol use during pregnancy and reduced IQ in children. Caution is needed, given non-significant estimates, limitations of self-reported data and concentrations reflect only recent use.

Per- and polyfluoroalkyl substances (PFAS) are environmental contaminants associated with higher serum lipids, although primarily in cross-sectional studies, limiting causal inference. We aim to determine whether there is a causal relationship between PFAS and serum lipid levels by emulating a target trial of a hypothetical PFAS-reduction intervention using observational data. The target trial would enroll adults aged ≥20 years without prior cardiovascular, kidney, or liver disease, diabetes, or use of related medications. Participants would be randomly assigned to either PFAS-reduction counseling or no counseling, with adherence evaluated after 10 years, and then followed up after 10 years to assess effects on serum lipids. To emulate the target trial, we will use data from the Copenhagen City Heart Study on three successive clinical visits: baseline, follow-up, and outcome assessment visit, 10 years apart. Eligible participants meet the target trial criteria, have available blood samples for PFAS quantification at follow-up, and information on serum lipids at the outcome assessment. Intervention strategies will be evaluated based on observed reductions in PFAS concentrations between baseline and follow-up visit. Serum lipids are assessed at the outcome assessment visit. The emulation assumes exchangeability by adjusting for baseline and time-varying confounders using G-computation. This protocol explores applying the target trial emulation framework to improve causal inference in environmental epidemiology.

BACKGROUND:Exposure to per- and polyfluoroalkyl substances (PFAS) has been associated with breast cancer, however findings have been conflicting and few studies have examined cancer subtypes or risk among subgroups of women. METHODS:We used an individually matched case-control design, nested within the Danish Diet Cancer and Health cohort. We identified 500 incident breast cancer cases with available plasma samples among postmenopausal women aged 50 to 64 years in the Danish Cancer Registry and for each case, we randomly selected from the study base one control woman enrolled within 180 days of the case and of the same age with an available sample. Plasma samples, taken at enrollment in 1993-97, were identified in the biobank and concentrations of PFAS were measured in 2025. Data were analyzed using logistic regression. RESULTS:No association between PFAS exposure and overall breast cancer was found with odds ratios per interquartile range of perfluorooctanoic acid (PFOA) = 0.89 (0.76-1.05), of perfluorohexane sulfonic acid (PFHxS) = 1.02 (0.98-1.06), of perfluorononanoic acid (PFNA) = 0.94 (0.87-1.02), of perfluoroheptanesulfonic acid (PFHpS) = 0.94 (0.79-1.11), of perfluorooctane sulfonate (PFOS) = 0.93 (0.78-1.11), and of N-ethyl perfluorooctane sulfonamido acetic acid (N-EtFOSAA) = 0.93 (0.79-1.09). Likewise, no clear association was observed for subtypes of breast cancer (ER, PR and HER2 status) nor with tumor size, or lymph node involvement. PFHpS, PFOS and N_EtFOSAA exposure was associated with a non-significant increased risk of breast cancer among current and previous hormone therapy (HT) users, whereas no association was found for never users. CONCLUSION:We found no association between exposure to six commonly used PFAS and overall breast cancer risk in postmenopausal women. The results indicated that exposure to some PFAS might be associated with increased risk of breast cancer among current/previous HT users. These results warrant replication in future prospective studies.

BACKGROUND:Per- and polyfluoralkyl substances (PFAS) have been used extensively in firefighting foams with resulting occupational exposure among firefighters. OBJECTIVE:To examine serum concentrations of PFAS among current and former employed and volunteer firefighters from the Danish fire services and Armed Forces. METHODS:During 2023-2024, 429 men from the Danish fire services and Armed Forces participated in the study. They were asked to provide a blood sample and fill in an online questionnaire. Concentrations of 15 PFAS were measured in serum. Measurements from the general population sampled in 2021 (the ENFORCE study) were used as reference. Associations between occupational factors and serum PFAS were assessed using multiple linear regression. RESULTS:Participants were from municipal fire services (n = 208), governmental fire services (n = 59), civilian airport fire services (n = 50), the air force (n = 98) and the navy (n = 14). Their median age was 50 years and median year of commencing service was 1999. While serum concentrations of PFAS among most participants were at level with those of the general population, civilian airport firefighters had higher serum concentrations of especially perfluorohexane sulfonic acid (PFHxS), perfluoroheptane sulfonic acid (PFHpS) and perfluorooctane sulfonic acid (PFOS). Age-adjusted geometric means were 1.42 ng/mL for PFHxS, 0.28 ng/mL for PFHpS and 6.92 ng/mL for total PFOS among civilian airport firefighters. CONCLUSION:Higher serum concentrations of PFHxS, PFHpS and PFOS among civilian airport firefighters likely reflected past occupational exposure to firefighting foam. Findings emphasized the importance of regulatory measures and substitution.

Studies have found associations between self-reported paracetamol use during pregnancy and shorter anogenital distance (AGD) in male infants, suggesting paracetamol have antiandrogenic properties. We investigated whether self-reported paracetamol use or quantified paracetamol concentration in maternal urine was associated with AGD in offspring from infancy to 9 years. In the Odense Child Cohort, women completed three questionnaires about paracetamol use during pregnancy and provided urine samples around GW28. AGDs were assessed in offspring at 3, 18 months, 3, 5, 7 and 9 years. Maternal self-reported paracetamol use was available for 931 boys and 793 girls with 6292 AGD measurements. Maternal urine concentrations were available for 281 boys and 233 girls with 2298 AGD measurements. Associations were analysed using propensity score-weighted linear regression adjusted for child height. 65 % of women reported using paracetamol during pregnancy. Detectable paracetamol was found in all participants, with 6 % (>4000 ng/ml) indicating recent use. Paracetamol concentrations indicating recent use were non-significantly associated with -1.71 % and -2.25 % shorter AGD in boys and girls. Self-reported paracetamol use anytime during pregnancy was significantly associated with -1.56 % shorter AGD in girls. Use before GW14 and between GW15-29 was non-significantly associated with -1.71 % and -1.79 % shorter AGD in boys, while use between GW15-29 and after GW30 was significantly associated with -2.52 % and -2.72 % shorter AGD in girls. The observed AGD changes were modest with little impact for the individual. However, as 65 % of pregnant women used paracetamol, these findings raise public health concerns given the increasing prevalence of reproductive disorders.

BACKGROUND:Perfluorinated alkyl substances (PFAS) are suggested to impair immune function in children. Previous studies investigating associations between prenatal PFAS exposure and common infections were performed in background-exposed populations whilst studies from high-exposed populations are lacking. OBJECTIVES:To investigate the association between prenatal PFAS exposure from contaminated drinking water and common infections in children aged 6 months to 7 years in Ronneby, Sweden. METHODS:The cohort included 17,051 children, born 2003-2013, to mothers residing in Blekinge County at least one year within the five years before childbirth. Primary care diagnoses of infections in eyes, ears, respiratory- and urinary tract were retrieved from the Blekinge Healthcare Register. The residential history of the mothers served as a proxy for prenatal exposure; very high, high, intermediate, and background. We estimated hazard ratios (HR) by Cox proportional hazards regression with the Andersen and Gill extension for recurring events. RESULTS:We observed an increased risk for ear infections (HR 1.28; 95% CI 1.03-1.58) in children with very high prenatal PFAS exposure, as well as suggestive but non-significant associations with eye- and urinary tract infections. Children with intermediate prenatal exposure had a reduced risk of eye infections (HR 0.86; 95% CI 0.77-0.95). No increased risk of respiratory tract infections was observed in any of the exposure categories. DISCUSSION:This study was the first to investigate the association between high prenatal PFAS levels and common infections diagnosed in primary care, and it adds to a growing body of evidence of the potential immunotoxicity of early-life PFAS exposure.

BACKGROUND:Pesticides are widespread in the environment and suspected endocrine disruptors that may interfere with sex hormones. Following the chlorpyrifos ban in 2020, use of alternative pesticides has increased; 2,4-Dichlorophenoxyacetic acid (2,4-D) remains widely used. This study examined the association between maternal pesticide exposure and pituitary, gonadal, and adrenal hormones in offspring during infancy. METHODS:We recruited pregnant women from 2010 to 2012 in the Odense Child Cohort, including 489 mother-child pairs. Maternal urinary concentrations of the generic pyrethroid metabolite 3-phenoxybenzoic acid (3-PBA), the chlorpyrifos metabolite 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. Associations between prenatal pesticide exposure and offspring reproductive hormones (expressed as age- and sex-specific standard deviation (SD) scores) were assessed using multivariate linear regression. RESULTS:In girls, higher maternal urinary TCPY and 2,4-D concentrations were associated with lower LH (-0.07 SD, 95 % CI: - 0.13; - 0.01 and - 0.06 SD, 95 % CI: - 0.11; - 0.02, per 1 µg/L increase, respectively); there were trends towards associations between 3-PBA, TCPY, 2,4-D and lower LH, FSH, E1 and E2, respectively. No associations were seen in boys. CONCLUSION:In this low-exposed cohort, prenatal exposure to chlorpyrifos and 2,4-D may affect the reproductive hormones in girls, but not boys, during minipuberty, which may have long-term implications. This is of public health concern given the fact that > 90 % of participants were exposed.

BACKGROUND:Per- and polyfluoroalkyl substances (PFAS) have been associated with an increased risk of infectious diseases. We aimed to investigate if in utero and early childhood exposure to PFAS was associated with the number of antibiotic prescriptions up to eight years of age. METHODS:Among 2448 singleton mother-child pairs from the Odense Child Cohort, 1425 had sufficient information on key variables and were included in the primary analysis. Information on redeemed antibiotic prescriptions from birth to eight years of age was obtained from the Danish National Prescription Registry. Longitudinal discrete-time Poisson models were used to quantify the relationship between PFAS and the number of antibiotic prescriptions redeemed. Analyses were carried out separately for PFAS measured in the mother during pregnancy and in the child at 18 months of age. Missing information was imputed using Multiple Imputation by Chained Equations. RESULTS:We observed no differences in the number of antibiotic prescriptions in the first eight years of life when comparing median and high PFAS concentrations measured in both pregnancy and at 18 months of age (rate ratio PFOA 1.01, 95 % confidence interval 0.94-1.08; PFOS 1.08, 0.98-1.19; PFNA 1.00, 0.94-1.07; PFDA 0.99, 0.94-1.04; PFHxS 1.02, 0.98-1.07). CONCLUSION:We found no association between in utero or early childhood PFAS concentrations and number of antibiotic prescriptions up to eight years of age. Antibiotic prescriptions may be an unspecific marker of childhood infections, hampering the possibility to observe an association with PFAS exposure. TRIAL REGISTRATION:Real World Evidence Registry: https://osf.io/dyqxm, registered March 8, 2023.

BACKGROUND:Di-n-hexyl phthalate (DnHxP) is one of the most potent phthalates with adverse effects on the male reproductive system. Despite a European ban on DnHxP since 2020, high urinary excretion of mono-n-hexyl phthalate (MnHxP), the major metabolite of DnHxP, has been observed in recent European human biomonitoring (HBM) studies. Sunscreen products containing the UV-filter diethylamino hydroxybenzyl hexyl benzoate (DHHB), which can be contaminated with DnHxP, were pointed out as a relevant source of exposure to DnHxP. OBJECTIVE:To study possible seasonal variation in urinary excretion of MnHxP in different Danish study populations. METHOD:MnHxP was measured by LC-MS/MS in 1591 urine samples collected in 2016-2022 from pregnant women, 7-year-old children, and infants and their parents participating in three different cohort studies. RESULTS:Urinary MnHxP was above the limit of detection (0.04 μg/L) in 84 % and above 1 μg/L in 33 % of samples. The 7-year-old children was the study population with the highest excretion rate (97 %). The highest urinary MnHxP concentration (72.5 μg/L) exceeded the health-based guidance value (HBM-I value) of 60 μg/L. A significantly higher urinary excretion of MnHxP was observed in the summer compared to the winter season in all study populations. 80 % of the urine samples with MnHxP concentrations > 1 μg/L were from the summer season. 40 % of Danish sunscreen products contain DHHB. CONCLUSION:The marked seasonal variation with higher MnHxP excretions in the summer season supports the hypothesis that the recently unveiled DnHxP contamination of the UV-filter DHHB in sunscreen products could be driving these exposures.

Vaginal candidiasis affects about 20 % of pregnant women and is usually treated with over-the-counter topical antifungal medication (azoles). Vaginal or transdermal application of azoles are absorbed and detectable in circulation. Azoles inhibit CYP51, which is crucial for the integrity of fungal cellular membranes. However, cell cultures have shown that azoles also affect steroidogenesis. This study investigated maternal antifungal application during pregnancy and the association with reproductive hormones during minipuberty and anogenital distance (AGD) the in the offspring from infancy to 9 years of age. In the Odense Child Cohort (2010-2012), women completed questionnaires about antifungal application during pregnancy. Serum concentrations of luteinising hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), estrone (E1), estradiol (E2), Δ4-androstenedione (adione), 17α-hydroxyprogesterone (17-OHP) and dehydroepiandrosterone-sulphate (DHEAS) were analysed in 454 infants at 3 months. AGD was assessed at 3, 18 months and 3, 5, 7 and 9 years of age, with 1792 measurements. Topical antifungal application during pregnancy was reported by 35 women. In boys, maternal application before GW 19 was associated with shorter AGD as well as lower adrenal hormone levels. In girls, application before GW 19 was associated with longer AGD and lower reproductive and adrenal hormone levels, while application after GW 19 was associated with shorter AGD, while hormone levels did not differ. Given the small number of cases, the findings should be interpreted with caution. The widespread use of over-the-counter antifungals appears to affect AGD and hormone production in offspring, which is concerning and may have long-term consequences for reproductive health.

OBJECTIVES:Firefighters face a range of hazards, including strenuous tasks in high-temperature environments and exposure to chemicals. These hazards may increase the risk of kidney diseases. However, limited evidence supports this hypothesis within this occupational group. Hence, this study aimed to assess the relationship between firefighting and kidney diseases. METHODS:A cohort comprising 10 094 male Danish firefighters was analysed, including 3455 full-time and 6639 part-time/volunteer firefighters. Diagnoses of kidney disease from 1994 to 2014 were retrieved from the Danish National Patient Registry. Morbidity among firefighters was compared with that of a sample of the male working population, and standardised incidence ratios (SIR) were used to estimate relative risks. RESULTS:The results indicated a positive association between full-time firefighting and urolithiasis (SIR 1.36; 95% CI 1.13 to 1.63). Shorter employment (<5 years) was associated with a higher risk of glomerulonephritis and chronic kidney disease, whereas longer employment (≥5 years) was linked to lower risks for most outcomes, except for urolithiasis, which remained elevated regardless of employment duration. Full-time specialised smoke divers were indicated to have a higher risk of glomerulonephritis, renal failure and chronic kidney disease. Urolithiasis risk was associated with an elevated risk in both regular and specialised full-time firefighters. Risk estimates for the assessed kidney diseases among part-time/volunteer firefighters generally reflected a lower risk. CONCLUSIONS:This study provides evidence for elevated risks of certain kidney diseases in full-time firefighters, especially urolithiasis. Awareness of sufficient hydration in relation to extreme heat exposures may be particularly important among firefighters.