Association between early prenatal exposure to ambient air pollution and birth defects: evidence from newborns in Xi'an, China.

BACKGROUND: The aim of this study was to investigate an association between birth defects and exposure to sulfur dioxide (SO2), nitrogen dioxide (NO2) and particles ≤10 µm in an aerodynamic diameter (PM10) during early pregnancy in Xi'an, China. METHODS: Birth defect data were from the Birth Defects Monitoring System of Xi'an, and data on ambient air pollutants during 2010-15 were from the Xi'an Environmental Protection Bureau. A generalized additive model (GAM) was used to investigate the relationship between birth defects and ambient air pollutants. RESULTS: Among the 8865 cases with birth defects analyzed, the overall incidence of birth defects was 117.33 per 10 000 infants. Ambient air pollutant exposure during the first trimester increased the risk of birth defects by 10.3% per 10 µg/m3 increment of NO2 and 3.4% per 10 µg/m3 increment of PM10. No significant association was found between birth defects and SO2. Moreover, NO2 increased risk of neural tube defects, congenital heart disease, congenital polydactyly, cleft palate, digestive system abnormalities and gastroschisis, and PM10 was associated with congenital heart disease and cleft lip with or without cleft palate. CONCLUSIONS: Chinese women should avoid exposure to high levels of NO2 and PM10 during the first 3 months of pregnancy.

[Study on the Hemoglobin levels among the Tibetan pregnant women in rural Lhasa].

OBJECTIVE: To understand the level of hemoglobin (Hb) and determine the risk factors of Hb concentration among the Tibetan pregnant women in rural Lhasa. METHODS: Between August 2008 and May 2011, a hospital-based study was conducted among 1 530 Tibetan pregnant women after getting their informed consent in agricultural and pastoral areas in maternity clinic or hospital in city, county and township level of Lhasa. Their blood samples were tested and related socio-demographic information was collected. Blood was collected on tip of finger and the Hb concentration was measured using B-Hemoglobin photometer. American Centers for Disease Control and Prevention(CDC) method was used to adjust the Hb measurements based on altitude for estimating the prevalence of anemia. Anemia was assessed according to WHO criteria. A hemoglobin concentration of less than 110 g/L in a pregnant woman was considered an indication of anemia. RESULTS: From August 2008 to May 2011, 1 530 Tibetan pregnant women living at (3 716.4 ± 69.1) m above sea level in rural Lhasa were examined. The findings indicated that average Hb concentration was (122.0 ± 17.5) g/L; the Hb concentration of 1(st), 2(nd) and 3(rd) trimester were (125.5 ± 18.0), (122.5 ± 16.9) and (120.6 ± 17.4) g/L, respectively. The Hb concentration of pregnant women decreased with the increase of gestational age(P < 0.05). Based onCDC method and the adjusted Hb level, the prevalence of anemia in pregnant women were 85.6% (1 310/1 530), the prevalence of anemia of 1(st), 2(nd), and 3(rd)rd trimester were 79.5% (206/259) , 86.1% (395/459)and 87.3% (698/800), respectively (P < 0.05) . The rate of moderate and severe anemia were 46.7% (612/1 310) among pregnant women. Multiple linear regression analysis showed that high Hb level was associated significantly with low family income status (ß = 2.74, 95%CI:1.73-3.74), no bad habits (drinking or smoking) (ß = 7.34, 95%CI:4.87-9.81) and fewer times of pregnancies(ß = -1.62, 95%CI:-2.93--0.31) after adjusting for potential confounding factors. CONCLUSION: Hb concentration level in pregnancy was rather low in rural Lhasa. The increase of family income, reduction the intervals of pregnancies and no bad habits might benefit for the improvement of Hb level of pregnant women in this region.

[The application of decision tree in the research of anemia among rural children under 3-year-old].

OBJECTIVE: To study the application of decision tree in the research of anemia among rural children. METHODS: In the Enterprise Miner module of software SAS 8.2, 3000 observations were sampled from database and the decision tree model was built. The model using decision tree of CART bases on Gini impurity index. RESULTS: The misclassification rate of decision tree model was, training set 21.2%, validation set 21.9%. The Root ASE of decision tree model was, training set 0.399, validation set 0.404. The area under the ROC curve was larger than the reference line. The diagnostic chart showed that the corresponding percentage was higher than the other. The decision tree model selected 9 important factors and ranked them by their power, among which mother of anemia (1.00) was the most important factor. Others were children's age (0.75), time of ablactation (0.53), mother's age (0.32), the time of egg supplementation (0.26), category of the project county (0.26), the time of milk supplementation (0.16), number of people in the family (0.13), the education status of the mother (0.12). Decision tree produced simple and easy rules that might be used to classify and predict in the same research. CONCLUSION: Decision tree could screen out the important factors of anemia and identify the cutting-points for factors. With the wide application of decision tree, it would exhibit important application values in the research of the rural children health care.

[The introduction of breastfeeding in children under age of three in the counties of western China in 2005].

OBJECTIVE: The study was to describe the breastfeeding status of children under the age of three in counties of western China and to provide evidence to the government for decision-making on intervention. METHODS: A cross-sectional study with probability-proportional-to-size (PPS) sampling method was used. The information on breastfeeding was obtained through memory of the mothers. Fourteen thousand and seventy-seven children were studied. Data on breastfed status in counties of western China was compared with those of the children from the survey of the counties of western China in 2001. RESULTS: The breastfeeding rate of children under 3 years old in western China was 96.5%. However, the overall breastfed rate of children under 6 months were only 33.4%, with rates of 11.4% and 22.0% on exclusively and predominantly breastfed groups respectively. Timely first-suckling rate was 43.5% with the continued breastfeeding rate (1 year) as 64.9%, but the continued breastfeeding rate (2 year) was only 9.7%. Reasons causing mothers to wean would include according to her own intention and to be able to attend the physical labor while exclusive breastfeeding under 6 months was for the growth and development of children, which might reduce the two-week prevalence of diarrhea. Major risks of exclusive breastfeeding of children under 6 months were seen as: level of education of the mothers, economic depression of the counties and mother's nationality (if as minority). CONCLUSION: Most of the children were ever or being breastfed at the time of interview with timely first-suckling took place earlier than in 2001. However continued breastfeeding did not last long. During these five years, the exclusive breastfeeding rate had been at low level, especially at the economic depression and the minority area.