Objective:To investigate the characteristics of urinary stones composition in children and the differences in their distribution among different sexes and age groups.Methods:The clinical data of 592 children with urinary stones who underwent stone composition analysis using infrared spectroscopy at Hunan Children's Hospital from October 2015 to October 2019 were retrospectively analyzed. There were 430 males and 162 females.The median age was 4.0 (0.3 to 18.0) years old. The stone composition and the differences in its distribution in different sex and age groups were analyzed.Results:A total of 643 urinary stones were analyzed in 592 cases, with 419 (65.2%) single-component stones and 224 (34.8%) mixed-component stones. The main stone components were calcium oxalate in 361 cases (56.1%), ammonium hydrogen urate in 130 cases (20.0%), cystine in 56 cases (8.7%), calcium phosphate in 33 cases (5.1%), uric acids in 33 cases (5.1%), magnesium ammonium phosphate in 25 cases (3.9%), and xanthine in 5 cases (0.8%). The percentage of calcium oxalate stones was higher in women than in men [65.6% (118/180) vs. 52.5% (243/463), P<0.05]. The proportion of upper urinary tract stones was higher in girl than in boy[93.4%(168/180) vs. 73.2%(339/463), P<0.05]. The differences in the composition ratios of calcium oxalate stones, ammonium hydrogen urate, cystine, and magnesium ammonium phosphate stones in different age groups were statistically significant ( P<0.05), with the highest proportion of calcium oxalate stones (35.6%) at 6 to 10 years of age, ammonium hydrogen urate and cystine stones at 1 to 2 years of age (45.4% and 42.9%), and magnesium ammonium phosphate stones at 3 to 5, 6 to 10, and 11 to 18 years of age, the percentage of urinary stones in children was 24%. Conclusions:The main component of urinary stones in children is calcium oxalate, followed by ammonium hydrogen urate and cystine. Age and gender correlate with the distribution of stone components. Calcium oxalate stones are common in females and in children aged 6 to 10 years, ammonium hydrogen urate and cystine stones are common in children aged 1 to 2 years, and magnesium ammonium phosphate stones are more common in children aged 3 to 5 years, 6 to 10 years, and 11 to 18 years.

Objective:To investigate the association between preterm birth, low birth weight and the risk of hypospadias.Methods:According to the search strategy of Cochrance Collaborative Network, the China National Knowledge Internet (CNKI), VIP, Wanfang, Pubmed, Cochrance and Embase were searched from the establishment of the database to April 2022. The literature on the relationship between preterm birth, low birth weight and the risk of hypospadias was included. Meta analysis was conducted on the relationship between preterm birth, low birth weight and the risk of hypospadias.Results:A total of 13 articles were included, including cases from Asia, Europe, Australia and America. Newcastle-ottawa Scale was used for evaluation, and the scores were all above 6. There were 10 articles on the relationship between preterm birth and the risk of hypospadias, all of which were case-control studies. Heterogeneity test I2=46%, P=0.05. There were 3 521 cases in the case group and 95 816 cases in the control group. Compared with the control group, preterm birth was a risk factor for hypospadias ( OR: 2.13, 95% CI: 1.89-2.41), and the difference was statistically significant ( Z=12.21, P<0.01). There were 11 articles on the association between low birth weight and the risk of hypospadias, all of which were case-control studies. Heterogeneity test I2=47%, P=0.04. There were 2 460 cases in the case group and 94 260 cases in the control group. Compared with the control group, low birth weight was a risk factor for hypospadias ( OR: 3.29, 95% CI: 2.57-4.22), and the difference was statistically significant ( Z=9.40, P<0.01). Conclusions:Based on meta-analysis of published literature, preterm birth and low birth weight increase the risk of hypospadias.