Dose-response relationship between blood lead levels and hematological parameters in children from central China.

BACKGROUND: Lead is a heavy metal that can affect the human hematological system. However, reports are limited on the dose-response relationship between blood lead levels (BLLs) and hematological parameters in children. This study aimed to explore the dose-response relationship between BLLs and hematological measurements among children in China. METHODS: A cross-sectional design was used. A total of 743 children aged 5-8 years were recruited from two counties in central China. The BLLs and blood levels of iron, zinc, and calcium were determined, and hematological parameters were measured. RESULTS: All hematological measurements and BLLs were logarithm-transformed to ensure a normal distribution. The geometric mean of the BLLs of all children was 82.4 µg/L. Forty-one percent of the children had BLLs ≥ 100 µg/L. The lead-poisoning percentages of the children were significantly associated with gender, age, district of residence, and environmental lead exposure level. Multivariate linear regression analyses showed no significant linear correlation between BLL and each hematological parameter among the children with BLLs ≥ 100 µg/L. The analyses also revealed a small increase in red blood cell count (RBC) with increasing BLLs in the BLLs < 100 µg/L group (ß = 0.03, P =  0.048). A negative association was noted between BLLs and blood platelet (PLT) count in the children with BLLs < 100 µg/L (ß = -0.90, P < 0.001). Logistic regression analyses showed that BLLs were significantly associated with decreased hemoglobin (Hb) levels, RBC counts, PLT counts and mean corpuscular hemoglobin (MCH) after adjusting for potential confounders. Such analyses also revealed a dose-response relationship between the BLLs and hematological parameters (Hb level, RBC count, and PLT count). The children with BLLs ≥ 100 µg/L were 2.72, 2.51, and 3.76 times more likely to achieve decreased RBC counts, Hb levels and PLT counts, respectively, compared to those with BLLs < 100 µg/L. Compared with children with BLLs < 100 µg/L, those with BLLs ≥ 100 µg/L were 3.16 and 4.38 times more likely to show decreased Hb levels and PLT counts respectively in the high-level lead-exposure group and 4.33 times more likely to achieve a decreased PLT count in the low-level lead-exposure group. The individuals with BLLs of the highest quartile were 3.65, 5.87, and 29.23 times more likely to exhibit decreased Hb levels, RBC counts, and PLT counts, respectively, than the children with BLLs of the lowest quartile. CONCLUSION: Our findings suggested a negative association between BLLs and hematological indicators (Hb level, RBC count, PLT count and MCH). A strong negative, non-linear dose-response relationship was also showed between BLLs and hematological parameters (Hb level, RBC count, and PLT count).

Association of Bone Turnover Levels with MTHFR Gene Polymorphisms among Pregnant Women in Wuhan, China.

Pregnancy is a critical stimulator of bone mineral resorption. We used to find the MTHFR gene polymorphisms are related with blood lead levels among pregnant women. Pregnancy-stimulated bone turnover may be associated with MTHFR gene polymorphisms too. In this article, we aimed to determine the relationship between MTHFR gene polymorphisms and bone turnover rates among the pregnant women. The participants including pregnant and non-pregnant women were selected and recruited during their routine prenatal or physical examination from July to October in 2012. A total of 1000 participants, including 250 pregnant women in the first, second, and third trimesters and 250 non-pregnant women, were enrolled in the study. Finally, after excluding 27 participants unable to provide blood samples, 973 eligible participants (i.e., 234,249, and 248 pregnant women in the first, second, and third trimesters, respectively, and 242 non-pregnant women) were included in the research. The MTHFR gene 1298CC homozygote carriers were more susceptible to yield higher plasma homocysteine levels than the 1298AA/AC carriers, with standardized coefficients of 0.086 (P<0.05) and 0.104 (P<0.01) of all the participants and the pregnant women, respectively. The MTHFR gene 1793AA homozygote carriers more likely showed higher plasma osteocalcin levels (standardized ß=0.091,P<0.01) than the 1793GG/GA carriers among all the subjects. Plasma homocysteine levels were positively correlated with blood lead levels among the participants and the pregnant women with standardized coefficients of 0.320 (P<0.01) and 0.179 (P<0.01), respectively. Plasma osteocalcin levels were positively associated with blood lead levels among pregnant and non-pregnant women with standardized coefficients of 0.084 (P<0.05) and 0.125 (P<0.01), respectively. In conclusion, homocysteine and osteocalcin contents in plasma are associated with the MTHFR gene A1298C polymorphism and blood lead levels among pregnant women. The MTHFR gene A1298C polymorphism-related homocysteine is a possible risk factor for increased blood lead levels among Chinese women.

Risk factors for low birth weight and preterm birth: A population-based case-control study in Wuhan, China.

Low birth weight (LBW) and preterm birth (PB) are associated with newborn mortality and diseases in adulthood. We explored factors related to LBW and PB by conducting a population-based case-control study from January 2011 to December 2013 in Wuhan, China. A total of 337 LBW newborn babies, 472 PB babies, and 708 babies with normal birth weights and born from term pregnancies were included in this study. Information of newborns and their parents was collected by trained investigators using questionnaires and referring to medical records. Univariate and logistic regression analyses with the stepwise selection method were used to determine the associations of related factors with LBW and PB. Results showed that maternal hypertension (OR=6.78, 95% CI: 2.27-20.29, P=0.001), maternal high-risk pregnancy (OR=1.53, 95% CI: 1.06-2.21, P=0.022), and maternal fruit intake ≥300 g per day during the first trimester (OR=1.70, 95% CI: 1.17-2.45, P=0.005) were associated with LBW. BMI ≥24 kg/m2 of mother prior to delivery (OR=0.48, 95% CI: 0.32-0.74, P=0.001) and gestation ≥37 weeks (OR=0.01, 95% CI: 0.00-0.02, P<0.034) were protective factors for LBW. Maternal hypertension (OR=3.36, 95% CI: 1.26-8.98, P=0.016), maternal high-risk pregnancy (OR=4.38, 95% CI: 3.26-5.88, P<0.001), maternal meal intake of only twice per day (OR=1.88, 95% CI: 1.10-3.20, P=0.021), and mother liking food with lots of aginomoto and salt (OR=1.60, 95% CI: 1.02-2.51, P=0.040) were risk factors for PB. BMI ≥24 kg/m2 of mother prior to delivery (OR=0.66, 95% CI: 0.47-0.93, P=0.018), distance of house from road ≥36 meters (OR=0.72, 95% CI: 0.53-0.97, P=0.028), and living in rural area (OR= 0.60, 95% CI: 0.37-0.99, P=0.047) were protective factors for PB. Our study demonstrated some risk factors and protective factors for LBW and PB, and provided valuable information for the prevention of the conditions among newborns.

Parity and All-cause Mortality in Women and Men: A Dose-Response Meta-Analysis of Cohort Studies.

To quantitatively assess the association between parity and all-cause mortality, we conducted a meta-analysis of cohort studies. Relevant reports were identified from PubMed and Embase databases. Cohort studies with relative risks (RRs) and 95% confidence intervals (CIs) of all-cause mortality in three or more categories of parity were eligible. Eighteen articles with 2,813,418 participants were included. Results showed that participants with no live birth had higher risk of all-cause mortality (RR= 1.19, 95% CI = 1.03-1.38; I(2) = 96.7%, P < 0.001) compared with participants with one or more live births. Nonlinear dose-response association was found between parity and all-cause mortality (P for non-linearity < 0.0001). Our findings suggest that moderate-level parity is inversely associated with all-cause mortality.