Association between dietary behavior and puberty in girls.

INTRODUCTION: Over the decades the trends of early onset of puberty have been observed in children, particularly in girls. Research evidence has reported diet to be among the most important risk factors for puberty onset. This study evaluated the association between dietary behavior and puberty in girls. METHODS: We enrolled 201 girls with the main complaints of breast development as the cases at the Endocrine Department of Nanjing Children's Hospital. The cases were divided into breast development with central priming and breast development without central priming groups and were matched with 223 normal health girls with no breast development (control group). We used the modified Child Eating Behavior Questionnaire (CEBQ) to conduct a face-to-face interview about dietary behavior. Sample t-test or Mann Whitney U test or Chi-square test, the analysis of variance or Kruskal Wallis test, and least significant difference (LSD) were used to compare differences between the groups, Bonferroni was used to correct the p-value, and logistic regression was used to analyze risk factors for puberty onset. RESULTS: A total of 424 girls participated in this study, among them, 136 were cases with breast development with central priming, 65 were cases with breast development without central priming, and 223 were normal health girls with no breast development. Age of the participants ranged from 4.5 to 9.3 years. There were significant differences in food response (p < 0.001), dietary restriction (p < 0.001), frequencies of vegetable intake (χ2 = 8.856, p = 0.012), drinking milk (χ2 = 23.099, p = 0.001), and borderline statistical difference in a total score of unhealthy dietary behavior (p = 0.053) among the cases and controls. However, in the post hoc analysis, these dietary behaviors were significant differences between the girls with breast development with central priming and the control groups. Moreover, girls in the breast development with central priming group had significantly higher bone age (BA), uterine body length, ovarian volume, basal luteinizing hormone (LH), basal follicle-stimulating hormone (FSH), peak LH, peak FSH, estradiol (E2), and free triiodothyronine (FT3) compared to those in the breast development without central priming group. In the multivariate logistic regression, only uterine body length was associated with increased risk of breast development with central priming (OR = 1.516, 95%CI: 1.243-1.850). CONCLUSION: There were significant differences in dietary behaviors among girls with breast development with central priming and normal health girls with no breast development, and uterine body length was associated with an increasing risk of breast development with central priming among girls with breast development.

Evaluation of multiple organophosphate insecticide exposure in relation to altered thyroid hormones in NHANES 2007-2008 adult population.

The thyroid gland is susceptible to chemical exposure such as organophosphate insecticides (OPIs). With the ubiquitous nature of these products, humans are simultaneously exposed to a multitude of chemicals. This study aimed to evaluate the association between an individual and a mixture of OPI metabolites and changes in serum thyroid hormone (TH) concentrations. The analyzed data were 1,434 participants from the United States National Health and Nutrition Examination Surveys (NHANES) cycle 2007-2008. Generalized linear model (GLM) regression, weighted quantile sum (WQS), and adaptive least absolute shrinkage and selection operator (adaptive LASSO) regression were used to investigate the associations between urinary OPI metabolites and altered serum THs. In GLM, all of the five urinary OPI metabolites were inversely associated with free triiodothyronine (FT3) among the male subjects; meanwhile, higher thyroglobulin (Tg) was related to dimethylphosphate (DMP). Moreover, in WQS models, the metabolite mixture induced FT3 down-regulation (ß = -0.209 (95% CI: -0.310, -0.114)), and caused an increased Tg concentration (ß = 0.120 (95% CI: 0.024, 0.212)), however, any significant association was observed among female participants. Consistently, the weighted index and LASSO coefficient demonstrated dimethylthiophosphate (DMTP) as the strongest metabolite in the FT3 model (mean weight= 3.449e-01 and ß =-0.022, respectively), and dimethylphosphate (DMP) represented the highest association in the Tg model (mean weight= 9.873e-01 and ß =-0.020, respectively). Further research is required to confirm our results and investigate the clinical impacts of these disruptions.

Blood pressure response to clonidine in children with short stature is correlated with postural characteristics: a retrospective cross-sectional study.

BACKGROUND: Clonidine stimulation test has been widely used in the diagnosis of growth hormone deficiency in children with short stature with a high level of reliability. However, it may cause hypotension, which usually appears as headache, dizziness, bradycardia, and even syncope. It is well known that elevating the beds to make patients' feet above their cardiac level might relieve this discomfort. However, the real efficiency of this method remains to be proved while the best angle for the elevated bed is still unclear. METHODS: A total of 1200 children with short stature were enrolled in this retrospective cross-sectional study. Age, gender, weight, and basic systolic and diastolic blood pressure were collected. Blood pressure at 1, 2, 3, and 4 h after stimulation tests were recorded. The participants were divided into 3 groups based on the angles of the elevated foot of their beds named 0°, 20°, and 40° groups. RESULTS: At one hour after the commencement of the tests, participants lying on the elevated beds showed a higher mean increase on the change of pulse pressure. The difference in the angles of the elevated beds did not show statistical significance compared with those who did not elevate their beds (0.13 vs. 2.83, P = 0.001; 0.13 vs. 2.18, P = 0.005; 2.83 vs. 2.18, P = 0.369). When it came to 4 h after the tests began, participants whose beds were elevated at an angle around 20° had a significantly higher mean increase in the change of pulse pressure values compared with those whose beds were elevated at an angle around 40° (1.46 vs. -0.05, P = 0.042). CONCLUSION: Elevating the foot of the beds of the patients who are undergoing clonidine stimulation tests at an angle of 20°might be a good choice to alleviate the hypotension caused by the tests.

Association between Urinary BPA Substitutes and Precocious Puberty among Girls: A Single-Exposure and Mixed Exposure Approach from a Chinese Case-Control Study.

There is an argument that BPA substitutes may have the same or more deleterious health effects as BPA due to their structural similarity. This study explored the association between urinary BPA substitutes and precocious puberty among girls by including 120 girls with precocious puberty (cases) aged 2-10 years enrolled at Nanjing Children's Hospital Department of Endocrinology in China between April 2021 to September 2021 and 145 healthy girls (controls) recruited from a primary school. Logistic regression was used to evaluate the effect of single exposures, and Bayesian kernel machine regression (BKMR) and quantile-based g-computation were used for the mixed effect. In the multivariate logistic regression, BPS (bisphenol S), TBBPA (tetrabromobisphenol A), and BPFL (bisphenol-FL) were significantly associated with increased risk of precocious puberty (odds ratio (OR) = 1.75, 95% confidence interval (CI): 1.13, 2.76, p = 0.014), (OR = 1.46, CI: 1.06, 2.05; p = 0.023), and (OR = 1.47, CI: 1.01, 2.18; p = 0.047), respectively. The BMKR and quantile-based g-computation models revealed consistent associations for single exposures and there was insufficient evidence for the associations of the mixed exposure of bisphenols with precocious puberty. In conclusion, BPA substitutes such as BPS, TBBPA, and BPFL may be associated with an increased risk of precocious puberty in girls.

The effect of environmental factors on precocious puberty in children: a case-control study.

BACKGROUND: Recently the prevalence of precocious puberty development is increasing among Chinese children. Proper understanding of the risk factors for precocious puberty in children is pivotal as could help to improve children's health. This study aims to evaluate the effect of environmental factors on precocious puberty in children. METHODS: We matched the cases and controls by age at the ratio of 1:1 (201 cases and 201 controls) for girls and 1:4 (24 cases and 96 controls) for boys. We used conditional logistic regression to explore the effect of environmental factors on precocious puberty, and a random forest model to identify the most important risk factor. RESULTS: In the multivariate regression, cesarean section (OR = 1.99, 95% CI: 1.05, 3.76), child body mass index [BMI] (OR = 1.25, 95% CI: 1.10, 1.43), maternal BMI (OR = 1.13, 95%CI: 1.01, 1.26), and exposure to secondhand smoke several times a month but less than once a week (OR = 4.09, 95%CI: 1.79,9.35), and almost every day (OR = 6.48, 95% CI: 2.14, 19.56) were risk factors for precocious puberty in girls. While maternal height (OR = 0.82, 95% CI: 0.75, 0.88), paternal height (OR = 0.91, 95% CI: 0.85, 0.98), bedtime at night (OR = 0.30, 95% CI: 0.17, 0.51), and night sleep (OR = 0.43, 95% CI: 0.21, 0.86) were protective factors. In boys, only exposure to secondhand smoke several times a month but less than once a week (OR = 7.94, 95% CI: 1.25, 50.33) was a risk factor for precocious puberty. In the random forest model, Child BMI was the most important risk factor for precocious puberty in girls. CONCLUSIONS: Our findings suggest that environmental factors were associated with precocious puberty in children, particularly in girls.

Efficacy of electrophysical agents in fibromyalgia: A systematic review and network meta-analysis.

OBJECTIVE: To examine the effectiveness of electrophysical agents in fibromyalgia. DATA SOURCES: CINAHL, Cochrane Library, Embase, Medline, PEDro, and Web of Science were searched from their inceptions to March 27, 2023. METHODS: This study was registered in PROSPERO (CRD42022354326). Methodological quality of included trials was assessed using PEDro scale, and the quality of evidence was determined according to the Grading of Recommendations Assessment, Development, and Evaluation system. The primary outcomes were pain, functional status, and mood. RESULTS: Fifty-four studies involving 3045 patients with fibromyalgia were eligible for qualitative synthesis and 47 (pain), 31 (functional status), and 26 (mood) for network meta-analysis. The network consistency model revealed that, when compared with true control, transcutaneous electrical nerve stimulation and microcurrent improved pain symptoms (P = 0.006 and P = 0.037, respectively); repetitive transcranial magnetic stimulation improved patient functional status (P = 0.018); and microcurrent (P = 0.001), repetitive transcranial magnetic stimulation (P = 0.022), and no treatment (P = 0.038) significantly improved mood after intervention. Surface under the cumulative ranking indicated that microcurrent was most likely to be the best for managing pain and mood (surface under the cumulative ranking: 70% and 100%, respectively); low-level laser therapy for pain and mood (80% and 70%, respectively); and repetitive transcranial magnetic stimulation for improving functional status and mood (80% and 70%, respectively). CONCLUSION: This review found low to moderate quality evidence that microcurrent, laser therapy, and repetitive transcranial magnetic stimulation are the most effective electrophysical agents for improving at least one outcome in fibromyalgia.

The effect of ambient ozone exposure on three types of diabetes: a meta-analysis.

BACKGROUND: Ozone as an air pollutant is gradually becoming a threat to people's health. However, the effect of ozone exposure on risk of developing diabetes, a fast-growing global metabolic disease, remains controversial. OBJECTIVE: To evaluate the impact of ambient ozone exposure on the incidence rate of type 1, type 2 and gestational diabetes mellitus. METHOD: We systematically searched PubMed, Web of Science, and Cochrane Library databases before July 9, 2022, to determine relevant literature. Data were extracted after quality evaluation according to the Newcastle Ottawa Scale (NOS) and the agency for healthcare research and quality (AHRQ) standards, and a meta-analysis was used to evaluate the correlation between ozone exposure and type 1 diabetes mellitus (T1D), type 2 diabetes mellitus (T2D), and gestational diabetes mellitus (GDM). The heterogeneity test, sensitivity analysis, and publication bias were performed using Stata 16.0. RESULTS: Our search identified 667 studies from three databases, 19 of which were included in our analysis after removing duplicate and ineligible studies. Among the remaining studies, three were on T1D, five were on T2D, and eleven were on GDM. The result showed that ozone exposure was positively correlated with T2D [effect size (ES) = 1.06, 95% CI: 1.02, 1.11] and GDM [pooled odds ratio (OR) = 1.01, 95% CI: 1.00, 1.03]. Subgroup analysis demonstrated that ozone exposure in the first trimester of pregnancy might raise the risk of GDM. However, no significant association was observed between ozone exposure and T1D. CONCLUSION: Long-term exposure to ozone may increase the risk of T2D, and daily ozone exposure during pregnancy was a hazard factor for developing GDM. Decreasing ambient ozone pollution may reduce the burden of both diseases.

Exposure to a mixture of personal care product and plasticizing chemicals in relation to reproductive hormones and menarche timing among 12-19 years old girls in NHANES 2013-2016.

The effects of co-exposure to personal care product and plasticizing chemicals (PCPPCs) on reproductive hormones and menarche timing has rarely been studied. We used Bayesian kernel machine regression (BKMR), adaptive least absolute shrinkage and selection operator (adaptive LASSO), and generalized linear model (GLM) to explore the mixture effects of 16 PCPPCs on reproductive hormones and early menarche among 297 girls aged 12-19 years in the National Health and Nutrition Examination Survey (NHANES) 2013-2016. In the BKMR, the mixture of PCPPCs was negatively and positively associated with testosterone (TT) and sex hormone-binding globulin (SHBG), respectively. In the adaptive LASSO, 2,5-dichlorophenol (2, 5-DCP), Mono (carboxyisoctyl) phthalate (MCOP), and Mono-benzyl phthalate (MBzP) were positively associated with estrogen (E2), whereas Mono-ethyl phthalate (MEP), Monoisobutyl phthalate (MiBP) and Mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) were inversely associated with E2. Bisphenol A (BPA) and MBzP were positively associated with SHBG, whereas Mono (carboxyisonony) phthalate (MCNP) and Mono (2-ethyl-5-carboxypentyl) phthalate (MECPP) were inversely associated with SHBG. In GLM, Benzophenone-3 (BZP) and MECPP were negatively associated with TT, whereas 2,4-dichlorophenol (2,4-DCP) revealed a positive association with early menarche onset. In conclusion, PCPPCs in the mixture and individually are associated with reproductive hormones and early menarche onset in girls.

Current situation of menstruation and gynecological diseases prevalence among Chinese women: a cross-sectional study.

BACKGROUND: Gynecological diseases have been taken attention and studied worldwide. Although, no recent studies have delineated the magnitude of gynecological diseases among Chinese women. This study aims to evaluate the current situation of menstruation and gynecological diseases prevalence among Chinese women. METHODS: A cross-sectional study was conducted at a hospital affiliated with Nanjing medical university in Nanjing, China between September 2021 and February 2022. A sample size of 977 women aged 18-52 years participated in a face-to-face interview questionnaire. Logistic regression was performed to determine whether pubertal timing and menstrual characteristics were associated with gynecological diseases. RESULTS: The most prevalent gynecological disease was dysmenorrhea (45.96%), followed by polycystic ovary syndrome, PCOS (19.04%), uterine fibroids (14.23%), spontaneous abortion (13.20%), trouble conceiving (12.59%), ovarian dysfunction (11.16%) and endometriosis (4.09%). In the adjusted model, heavy bleeding with large clots was associated with an increased risk of dysmenorrhea (odds ratio, OR = 5.01, 95% Confidence interval, CI 2.26, 11.10; p = 0.000), while history of precocious puberty diagnosis was associated with a reduced risk of dysmenorrhea (OR = 0.50, 95%CI: 0.26, 0.94; p = 0.031). Regular menstrual cycle in the past 12 months and regular menstrual periods were associated with decreased risk of PCOS (OR = 0.44, 95%CI 0.30, 0.65; p = 0.000) and (OR = 0.52, 95%CI 0.36, 0.74; p = 0.000), respectively. Histories of early thelarche, early menarche, and precocious puberty diagnosis were associated with increased risk of ovarian dysfunction (OR = 1.96, 95%CI 1.25, 3.08, p = 0.004), (OR = 2.26, 95%CI 1.24, 4.13; p = 0.008) and (OR = 2.79, 95%CI 1.36, 5.74; p = 0.005), respectively. Heavy bleeding and heavy bleeding with large clots were associated with endometriosis (OR = 4.92, 95%CI 1.50, 16.15, p = 0.009) and (OR = 5.67, 95%CI 1.42, 22.56; p = 0.014), respectively. CONCLUSIONS: The prevalence of gynecological diseases is increasing among Chinese women and pubertal timing and menstrual characteristics may be associated with some gynecological diseases, specifically dysmenorrhea, PCOS, ovarian dysfunction, and endometriosis.

Association between Exercise and Blood Pressure in Hypertensive Residents: A Meta-Analysis.

BACKGROUND: Exercise is recommended as an effective lifestyle behaviour for adults to prevent and treat hypertension. In this study, a randomized-effect meta-analysis was used to analyse the influence of exercise interventions on blood pressure in patients with hypertension. METHODS: Candidate papers were retrieved from PubMed, Web of Science, Embase, and Cochrane Library electronic databases, and 46 studies were finally included and analysed. RESULTS: It was shown that preplanned walking (systolic blood pressure (SBP): WMD (weighted mean difference) = -5.94, 95% CI: -8.57, -3.30; diastolic blood pressure (DBP): WMD = -2.66, 95% CI: -3.66, -1.67), yoga (SBP: WMD = -5.09, 95% CI: -9.28, -0.89; DBP: WMD = -3.06, 95% CI: -5.16, -0.96), aquatic sports (SBP WMD = -7.53, 95% CI: -11.40, -3.65; DBP: WMD = -5.35, 95% CI: -9.00, -1.69), and football (SBP: WMD = -6.06, 95% CI: -9.30, -2.82; DBP: WMD = -5.55, 95% CI: -8.98, -2.13) had significant effects on blood pressure reduction. However, Tai Chi (SBP: WMD = -8.31, 95% CI: -20.39, 3.77; DBP: WMD = -3.05, 95% CI: -6.96, 0.87) and Qigong (SBP: WMD = -4.34, 95% CI: -13.5, 4.82; DBP: WMD = -3.44, 95% CI: -7.89, 1.01) did not significantly reduce blood pressure. The heterogeneity of the meta-analysis was high. CONCLUSION: Walking, yoga, aquatic sports, and football were feasible and independent lifestyle interventions, and they were effective options for treating hypertension. More scientifically designed randomized controlled trials are needed in the future to further compare different forms of exercise for the treatment of hypertension.

Effect of Maternal Triclosan Exposure on Neonatal Birth Weight and Children Triclosan Exposure on Children's BMI: A Meta-Analysis.

Background: Triclosan (TCS) is an environmental chemical with endocrine disrupting effects and can enter the body through the skin or oral mucosa. Human data about the effect of TCS exposure during pregnancy on neonatal birth weight and TCS exposure during childhood on children's growth are scarce. Objectives: To investigate the association between maternal urinary TCS level and neonatal birth weight, as well as children's urinary TCS level and children's body mass index (BMI). Methods: A systematic literature search was conducted using PubMed, Cochrane Library, and Web of Science. Finally, seven epidemiological articles with 5,006 participants from September 25, 2014 to August 10, 2018 were included in the meta-analysis to identify the relationship between maternal exposure to TCS and neonatal birth weight. On the other hand, three epidemiological articles with 5,213 participants from July 22, 2014 to September 1, 2017 were included in another meta-analysis to identify the relationship between children's exposure to TCS and children's BMI. We used Stata 16.0 to test the heterogeneity among the studies and calculating the combined effect value 95% confidence interval (CI) of the selected corresponding models. Results: TCS exposure during pregnancy was not significant associated with neonatal birth weight. The results of forest plots were as follows: ES (Estimate) = 0.41 (95% CI: -11.97-12.78). Children's urinary TCS level was also irrelevant associated with children's BMI: ES = 0.03 (95% CI: -0.54-0.60). Conclusions: This meta-analysis demonstrated that there was no significant association between maternal TCS level and neonatal birth weight, also there has no relationship between children's urinary TCS level and children's BMI.

Effects of exposure to urban particulate matter SRM 1648a during pregnancy on the neurobehavioral development of offspring mice.

The development of the nervous system is crucial to a child's health. However, the nervous system is also susceptible to a variety of factors during development. To date, epidemiological studies have reported controversial results on the relationship between prenatal exposure to particulate matter (PM) and neurobehavioral development. Thus, we investigated the effect of PM exposure during pregnancy on the neurobehavioral development of offsprings. Adult C57BL/6 mice were exposed to PM from gestation day (GD) 0.5-21 by the intratracheal instillation. The daily exposure doses were 250 µg/kg.b.w and 2500 µg/kg.b.w respectively. The offspring mice began behavioral tests at the 5th week. We assessed neurobehavioral development, and the gene expression level changes in the mouse hippocampus using RNA-seq. In the open field test, the movement distance in the central area was significantly decreased in the high-dose group. Serum free triiodothyronine (FT3) levels were significantly increased in male offspring mice with prenatal high-dose PM exposure. The RNA-seq results suggested that the Prkca, Med12l, Ep300, and Slc16a10 in the thyroid hormone signaling pathway were significantly decreased in offspring mice in the high-dose group. Our data showed that prenatal PM exposure caused the offspring mice's anxiety-like behaviors and increased serum FT3 levels. The changes in thyroid hormone pathway-related genes might be the causes of the above series of changes.

Association between mercury exposure and thyroid hormones levels: A meta-analysis.

BACKGROUND: The relationship between mercury (Hg) exposure and thyroid hormones (THs) levels in the general population has been inconclusive. We conducted a random effects model meta-analysis to identify the association between Hg exposure and THs levels in the general population. METHODS: This meta-analysis were performed based on the PECO questions (P = general population; E =1ug/L Hg in blood and urine; C =1ug/L incremental increase on; and O = variation of THs levels). We searched four electronic databases including PubMed, Web of Science, Embase, and Cochrane Library for studies published on or before 20th July 2020. Prospective and cross-sectional studies that evaluated the association between Hg exposure and the levels of thyroid stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), and free thyroxine (FT4) were included. We also assessed aggregate risks for the reliability of the included studies. RESULTS: Initially, we retrieved 4889 articles. 18 studies met our inclusion criteria after screening and 13 articles were eligible to be included in the meta-analysis. The meta-analysis results suggest that blood Hg may be significantly associated with THs levels. The presence of Hg in blood may significantly increase the levels of TSH (ß=0.55; 95%CI: 0.20,0.90; p < 0.001) and FT4 (ß=0.47; 95%CI: 0.11,0.82; p < 0.001), with the opposite association in T4 (ß=-0.02; 95%CI: 0.02, -0.01; p < 0.001). For the subgroup analysis, blood Hg was positively correlated with TSH levels in children and adolescents (ß=0.62; 95%CI: 0.09, 1.15; p < 0.001) and FT4 levels in pregnant women (ß=1.00; 95%CI: 0.99, 1.00; p < 0.001) respectively. CONCLUSIONS: This meta-analysis indicates that exposure to Hg in blood could significantly corrrelate with the levels of TSH, T4, and FT4 in the general population. Therefore, it is crucial to control the use of Hg and strengthen protection of the thyroid.

Differences of blood cells, lymphocyte subsets and cytokines in COVID-19 patients with different clinical stages: a network meta-analysis.

BACKGROUND: Due to the rapid spread of coronavirus disease 2019 (COVID-19) worldwide, it is necessary to ascertain essential immune inflammatory parameters that describe the severity of the disease and provide guidance for treatment. We performed network meta-analyses to determine differences in blood cells, lymphocyte subsets, and cytokines in COVID-19 patients with different clinical stages. METHODS: Databases were systematically searched to May 2, 2020, and updated on June 1, 2020. Network meta-analyses were conducted via Stata 15.0, and the mean difference (MD) and its 95% CI were used as the effect values of the pooled analysis. RESULTS: Seventy-one studies were included involving 8647 COVID-19 patients, White blood cell (WBC), neutrophil (NEUT), IL-6, and IL-10 counts increased significantly with worsening of the COVID-19, while lymphocyte (LYM) counts decreased. The levels of platelet (PLT), CD3+, CD4+, CD8+, and CD19+ cells in severe and critical patients were significantly lower than those in mild patients. IL-1ß count was significantly elevated in critical patients. CONCLUSIONS: Immune suppression and inflammatory injury play crucial roles in the progression of COVID-19, and the identification of susceptible cells and cytokines provide guidance for the early and accurate treatment of COVID-19 patients.

Association between phenols exposure and earlier puberty in children: A systematic review and meta-analysis.

OBJECTIVE: To identify the association between phenolic chemicals and the risk of earlier puberty based on the available evidence by systematic review and meta-analysis. METHODS: Databases PubMed, Web of Science, and Cochrane Library were searched and retrieved appropriate journal articles on the association between phenols exposure and earlier puberty in children published before February 14, 2020. Stata software version 12.0 and Excel were used for statistical analysis. RESULTS: Nine studies were included in the meta-analysis with total subjects of 4737. All the subjects included in our studies were girls. The pooled estimate has shown the association between 2, 5- dichrolophenol exposure, and earlier puberty in children with effect size (ES) 1.13 (95% CI: 1.06, 1.20). Exposed to other types of phenolic chemicals such as bisphenol A, Triclosan, Benzophenone-3 were not statistically significant associated with the risk of earlier puberty in children with the overall pooled estimates of ES of 1.09 (95%CI: 0.88, 1.35), ES 1.05(95% CI: 0.96, 1.15), and ES 0.98 (95% CI: 0.88, 1.10) respectively. CONCLUSION: Our results portray that phenols particularly 2, 5- dichlorophenol exposure might be associated with the risk of earlier puberty in children. Also, caution should be taken to other type of phenolic chemicals since in subgroup analysis some individual studies have shown a positive relationship between bisphenol A, Triclosan and Benzophenone-3 exposures, and the risk of earlier puberty in children. Future cohort studies should be conducted with more sample sizes to determine the relationship between 2, 5- dichlorophenol, and the risk of earlier puberty in children of all gender.