Intrauterine growth retardation (IUGR) is a major complication of pregnancy and is the second leading cause of perinatal morbidity and mortality. The etiology of IUGR is multifactorial and the maternal factors are easily identifiable and modifiable. The present study aimed to perform a meta-analysis to identify the association between various maternal factors and IUGR. Eight electronic databases (PubMed, Cochrane, Embase, CIHNAL Plus, CNKI, VIP database, CBM, and WanFang database) were searched from their inception until July 2020. Eligibility screening, data extraction, and quality assessment of the retrieved articles were conducted independently by two reviewers. The Newcastle-Ottawa Quality Assessment Form and the Joanna Briggs Institute critical appraisal tool were used to evaluate the quality of included studies. The outcomes of study were calculated by OR with 95%CI. The study protocol was registered with PROSPERO (No. CRD42020210615). A total of 15 studies were included, with a sample size range from 152 to 9372. The quality of included studies ranged from moderate to high. The pooled results identified seven factors: smoking (OR = 1.62, 95%CI 1.38-1.90), primiparity (OR = 1.64, 95%CI 1.20-2.24), and prepregnancy.BMI < 18.5 (OR = 1.98, 95%CI 1.29-3.03), anemia (OR = 2.01, 95%CI 1.44-2.82), hypoproteinemia (OR = 2.91, 95%CI 1.94-4.36), pregnancy-induced hypertension (OR = 3.45, 95%CI 1.80-6.58), and maternal gestational weight gain (OR = 2.51, 95%CI 1.88-3.35). The present study identified several maternal factors for IUGR: smoking, primiparity, prepregnancy BMI < 18.5, poor gestational weight gain, PIH, anemia, and hypoproteinemia. The result could serve to generate risk factors prediction models, improve the management and education for child-bearing or early pregnant women.

Background: Several studies have revealed a positive correlation between a Helicobacter pylori (HP) infection and the risk of non-alcoholic fatty liver disease (NAFLD). This meta-analysis was conducted to explore further the relationship between HP infection and NAFLD in the Asian and non-Asian populations. Methods: Relevant studies published from inception to July 22, 2021, in the following databases: PubMed, EMBASE, the Cochrane library, and Web of Science were comprehensively searched. The odds ratio (OR) and hazard ratio (HR) with a 95% confidence interval (95%CI) were pooled by the random-effects model or fixed-effects model. Additionally, subgroup and sensitivity analyses were performed. The funnel plot and the Egger test were used to estimate publication bias. Results: This meta-analysis included 25 studies involving 107,306 participants. Positive associations between HP infection and NAFLD were found both for the Asian (OR = 1.30, 95% CI: 1.13-1.49, P < 0.01; I-2 = 94.30%, P < 0.01) and non-Asian populations (OR = 1.42, 95% CI: 1.04-1.94, P = 0.03; I-2 = 44.90%, P = 0.09). Moreover, similar results were observed in the Asian female group (OR = 1.31, 95% CI: 1.17-1.46, P < 0.01; I-2 = 46.30%, P = 0.07) but not for the Asian male group. Subgroup analyses for the Asian population showed that there were differences in the association among NAFLD diagnosis methods (P < 0.01) and the study design (P < 0.01). However, subgroup and sensitivity analyses results showed that the association for the non-Asian population was not stable enough. Conclusions: The data obtained in this systematic review and meta-analysis suggested that an HP infection was associated with an increased risk of NAFLD for Asian and non-Asian populations. However, the association was not found for Asian males. Further studies are required to establish the causal association, especially for the non-Asian population.

Background and objective: Recently, several studies have investigated the prevalence of chronic obstructive pulmonary disease (COPD) at high altitude (>1,500 m). However, much remains to be understood about the correlation between altitude and COPD. We aimed to summarize the prevalence of COPD at high-altitudes and find out if altitude could be a risk factor for COPD. Methods: We searched PubMed/Medline, Cochrane Library, Web of Science, SCOPUS, OVID, Chinese Biomedical Literature Database (CBM) and Embase databases from inception to April 30th, 2019, with no language restriction. We used STATA 14.0 to analyze the extracted data. A random-effect model was used to calculate the combined OR and 95% CI. Heterogeneity was assessed by the I 2 statistic versus P-value. We performed a subgroup analysis to analyze possible sources of heterogeneity. The Egger's test and the Begg's test were used to assess any publication bias. Results: We retrieved 4,574 studies from seven databases and finally included 10 studies (54,578 participants). Males ranged from 18.8% to 49.3% and the population who smoked ranged from 3.3% to 53.3%. The overall prevalence of COPD at high-altitude was 10.0% (95% CI [0.08-0.12], P < 0.001). In a subgroup analysis, based on different regions, the results showed that the prevalence in Asia was higher than that in Europe and America. Seven studies compared the relationship between the prevalence of COPD at high-altitudes and the lowlands. The results showed that altitude was not an independent risk factor for the prevalence of COPD (ORadj = 1.18, 95% CI [0.85-1.62], P = 0.321). There was no publication bias among the studies. Conclusions: Our study found a higher prevalence of COPD at high-altitudes than those from average data. However, altitude was not found to be an independent risk factor for developing COPD (PROSPERO Identifier: CRD42019135012).