Ambient air pollution and adverse birth outcomes: a systematic review and meta-analysis.

Several reviews have assessed the relationship between exposure to ambient air pollution and adverse birth outcomes during pregnancy, but the results remain controversial. The objective of this study was to assess this correlation quantitatively and to explore sources of heterogeneity. We included all published case-control or cohort studies that evaluated the correlation between ambient air pollution and low birth weight (LBW), preterm birth (PTB), and small for gestational age (SGA). Analytical methods and inclusion criteria were provided on the PROSPERO website (CRD42018085816). We evaluated pooled effects and heterogeneity. Subgroup analyses (grouped by exposure period, study settings, study design, exposure types, data source, Newcastle-Ottawa quality score (NOS), and adjustment for smoking or meteorological factors) were also conducted and publication bias was examined. The risk of bias in systematic reviews (ROBIS) tool was used to evaluate the overall risk of bias in this review. Forty studies met the inclusion criteria. We observed pooled odds ratios (ORs) of 1.03-1.21 for LBW and 0.97-1.06 for PTB when mothers were exposed to CO, NO2, NOx, O3, PM2.5, PM10, or SO2 throughout their pregnancy. For SGA, the pooled estimate was 1.02 in relation to NO2 concentrations. Subgroup analysis and sensitivity analysis decreased the heterogeneity to some extent, such as the subgroups of continuous measures (OR=0.98 (0.97-0.99), I2=0.0%) and NOS>7 (OR=0.98 (0.97-0.99), I2=0.0%) in evaluating the association between PTB and NO2. This review was completed with a low risk of bias. High concentrations of air pollution were significantly related to the higher risk of adverse birth outcomes. However, the sources of heterogeneity among studies should be further explored.

Complementary feeding patterns among ethnic groups in rural western China.

OBJECTIVE: This study investigated complementary feeding practices among four ethnic groups (Han, Uygur, Tibetan, and Zhuang) based on a cross-sectional survey in rural western China. METHODS: In 2005, a stratified multistage cluster random sampling method was used to recruit 9712 children (7411 Han, 1032 Uygur, 678 Tibetan, and 591 Zhuang) between 6 and 35 months of age and their mothers from 45 counties in 10 provinces (autonomous regions, municipalities) in western China. RESULTS: The rates of early introduction (before 6 months) of complementary foods in four ethnic groups (Han, Uygur, Tibetan, and Zhuang) were 71.30%, 95.95%, 82.40%, and 72.30%, respectively. The Infant and Child Feeding Index (ICFI) for Uygur and Tibetan children was lower than that for Han children at all age groups. Uygur children were more likely to have unqualified ICFI compared with Han children in a multivariate logistic regression (odds ratio (OR)=5.138, 95% confidence interval (CI): 4.340-6.084). A higher level of maternal education, greater family wealth, and the availability of complementary feeding educational materials decreased the likelihood of an unqualified ICFI. The nutritional status of children (Han, Tibetan, and Zhuang) with qualified ICFI was better than that for children with unqualified ICFI. CONCLUSIONS: Appropriate interventions are required to improve complementary feeding practices in rural western China.

[Study on maternal health care status to agricultural and nomadic counties in Tibet Autonomous Region of China].

OBJECTIVE: To understand the current situation of maternal health care and the association between maternal health care and relevant factors. METHODS: According to a cross sectional study design, 1512 mothers having children under 3 years old were drawn under stratified random sampling method and interviewed at their households in 15 counties, Tibet Autonomous Region of China. RESULTS: 77.6% of the pregnant women received at least one antenatal checkup with an average of 3.89 times while the rate of antenatal checkup over 5 times was 26.3%. The hospital delivery rate was 40.4% in this area. 83.9% of the women received education under the health care program during pregnancy and 66.2% of them were visited by health workers after delivery. Major factors of the antenatal checkups would include the resource of income, living in nomadic area, personal sanitation, antenatal health care education, mobilization of delivery at hospital, knowledge of antenatal health care etc. CONCLUSIONS: There had been great improvement in women's health care in this area as compared with the status in 1999, but the frequency of receiving antenatal checkup was still not enough and the rate of hospital delivery was also low as compared with 46 counties in western areas of China. Poor knowledge of health care during pregnancy seemed to be the major factor that limited the utilization of antenatal health care. Knowledge on health and common sense of health care should be disseminated to improve the antenatal care and to enhance the hospital delivery rate.

[Assessment on nutritional status among children under 3 years using anthropometry in 40 counties of western China].

OBJECTIVE: To assess nutritional status among children younger than 3 years in 40 counties of western China, using anthropometry. METHODS: With cross-sectional study and random sampling, a survey with a sample size of 7252 was conducted in 40 counties of western China on children under 3 years old. Height and weight were measured and nutrition status was evaluated with WHO/NCHS reference using Z scores. RESULTS: SD of height for age (HA) and weight for age (WA) were 1.10 - 1.30 and 1.06 - 1.40, respectively and SD of WAZ for infants varied. The distribution of HA Z and WAZ shifted downward to 1 unit and 0.4 unit for distribution of weight for height (WHZ). The prevalence of stunting, underweight and wasting were 23.0%, 22.6% and 7.5% respectively. The prevalence rates were low among those yourger than 3 months. Stunting and underweight increased sharply after 6 months and reached 20% - 30%. Significant correlation was found between underweight and stunting or wasting with coefficients of 0.815 and 0.636, respectively. No correlation was found between stunting and wasting. CONCLUSION: The nutrition status adversely affected children as a whole but not only for individuals. There was a higher prevalence of malnutrition mainly on low height to children. Weight for age must be interpreted cautiously because of the inability of this indicator in distinguishing stunting and wasting just by itself. Assessment by anthropometry called for accurate information on age and measurement of height and weight.