Background: Ambient air pollution is closely related to a variety of health outcomes. Few studies have focused on the correlations between air pollution exposure and children’s sexual development. In this study, we investigated the potential effects of exposure to air pollution on precocious puberty among children using real-world evidence. Methods: We conducted a case-crossover study (n = 2201) to investigate the effect of ambient air pollution exposure on precocious puberty from January 2016 to December 2021. Average exposure levels of PM2.5, PM10, SO2, NO2, CO, and O3 before diagnosis were calculated by using the inverse distance weighting (IDW) method. Distributed lag nonlinear model (DLNM) was used to assess the effect of air pollutants exposure on precocious puberty. Results: The mean age of the children who were diagnosed with precocious puberty was 7.47 ± 1.24 years. The average concentration of PM2.5 and PM10 were 38.81 ± 26.36 μg/m3 and 69.77 ± 41.07 μg/m3, respectively. We found that exposure to high concentrations of PM2.5 and PM10 might increase the risk of precocious puberty using the DLNM model adjusted for the age, SO2, NO2, CO, and O3 levels. The strongest effects of the PM2.5 and PM10 on precocious puberty were observed in lag 27 (OR = 1.72, 95% CI: 1.01–2.92) and lag 16 (OR = 1.95, 95% CI: 1.33–2.85), respectively. Conclusion: Our findings supported that short-term exposure to air pollution was the risk factor for precocious puberty. Every effort should be made to protect children from air pollution.

ObjectiveTo describe the thyroid function test among children with abdominal distention and to follow up the treatment received by children with abnormal thyroid function.DesignCross-sectional study.Setting and participantsA total of 1089 children (median age:30 days (IQR=21–60 days) with abdominal distension were included in this single centre study in Nanjing, China.ResultThyroid dysfunction was found in 43 of 148 Hirschsprung’s disease (HSCR) cases, with 3 (2.03%) having hypothyroidism, 3 (2.03%) having subclinical hypothyroidism and 3 (2.03%) having subclinical hyperthyroidism. Thyroid dysfunction was found in 206 of 941 functional abdominal distension cases, with 4 (0.43%) having hypothyroidism, 23 (2.4%) having subclinical hypothyroidism, 28 (2.9%) having subclinical hyperthyroidism and 1 (0.11%) having hyperthyroidism. Among total 65 cases (9 from HSCR, 56 from functional abdominal distension) diagnosed with thyroid diseases, 12 were treated with levothyroxine (LT-4), of which 9 were discontinued treatment at about 2 years old, and 3 were still receiving LT-4. Thirty-two cases received no treatment and thyroid function returned to normal in about 1 month. Twenty-one cases were lost during the follow-up.ConclusionThe paediatrician should be vigilant for hypothyroidism when dealing with children with abdominal distension. Thyroid function should be followed up rather than simply administering a short-term levothyroxine treatment.

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