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Background: To examine whether blood pressure (BP) in the preconceptional period was associated with preterm birth in Chinese women., Methods: The data are from a large population-based cohort study established to evaluate the effectiveness of the campaign to prevent neural tube defects in 21 Chinese counties. We included 44 494 singleton live births delivered at gestational ages of 20-42 weeks to women who were registered before pregnancy in seven counties in southern China. Blood pressure was measured during registration by trained healthcare workers. We used logistic regression to evaluate the associations between prepregnancy blood pressure and increased risk of preterm birth, adjusting for potential confounders., Results: The study size had 93% power (α=0.05) to detect an increase of 38% over the unexposed rate of 5.32% for preterm birth. The prevalence of hypertension of study population in prepregnancy was 4.55% (2023/44 494). The incidence of preterm birth was 5.73% for hypertension group and 5.32% for nonhypertension group. Compared with nonhypertension group, hypertension group did not show significant increased risk for preterm birth overall [adjusted risk ratio (RR)=1.10, 95% confidence interval (CI) 0.91-1.34], iatrogenic subtype [adjusted RR=1.21, 95% CI 0.78-1.88], or noniatrogenic subtype [adjusted RR=1.08, 95% CI 0.88-1.34]. When the participants with normal blood pressure were used as the reference, the adjusted RRs of noniatrogenic preterm birth were 0.79 (0.70-0.89) for prehypertensive women., Conclusion: Our results do not support the association between hypertension or higher blood pressure prior to pregnancy and the increased risk of preterm birth.

Background: Increasing evidence suggest that active smoking is a risk factor for hypertension, but little is known about the effects of passive smoking on this condition. In China, female passive smoking is widespread and severe due to the high proportion of men who smoke, particularly in rural areas. This study assessed whether passive smoking is associated with increased risk of hypertension among nonsmoking women in rural China., Methods: A total of 392 nonsmoking women from a rural area of Shanxi Province (northern China) participated in this cross-sectional study. Data on female passive smoking, and other factors known to influence hypertension, were collected during face-to-face interviews. Logistic regression was used to evaluate the association analyses after adjusting for potential confounders., Results: In total, 162 of the 392 participants were hypertensive (41.3%); 118 participants (30.1%) reported exposure to passive smoking, of whom 88.4% were exposed to smoke in the home. After adjusting for age, BMI, education, occupation, drinking status, physical activity, and menopause status, passive smoking conferred an approximately two-fold risk increase of hypertension (adjusted odds ratio = 1.99, 95% confidence interval 1.16, 3.39). The adjusted odds ratios for passive smoking exposure levels of one to three, four to six, and more than six occasions per week were 1.01 (0.39-2.62), 2.57 (1.05-6.30), and 2.59 (1.18-5.69), respectively., Conclusion: In rural areas of northern China, female passive smoking in the home is prevalent. Frequent exposure to secondhand smoke is a risk factor for hypertension among nonsmoking women, which suggests that measures should be taken to prevent passive smoking among this population.

Emissions of complex mixtures of polycyclic aromatic hydrocarbons (PAHs) and other compounds into the environment represent a potential threat to the health of humans. Information regarding the dose and duration of exposure is essential to determine the degree of risk and to identify sensitive receptors within a population. Although measurements of chemical concentrations in air may be used to estimate exposures, internal biomarkers provide more accurate information regarding the dose of exposure and retention of toxic chemicals. This study was conducted in a population in rural China exposed to PAHs from a variety of sources. The study population was located in an area known to have an elevated incidence of birth defects. Parents of children born with a neural tube defect (NTD) were recruited as case participants and parents of children born with no visible birth defect were recruited as controls. The study was designed to test the hypothesis that parents of children born with a NTD would exhibit a biomarker of exposure at higher levels than the parents of a child with no visible birth defect. A total of 35 mothers and 32 fathers were recruited as case participants, and 18 mothers and 19 fathers were recruited as control participants. Venous blood was collected from the study participants by hospital staff as soon as possible following the birth of the child. PAHs were isolated from the whole blood by solvent extraction and DNA was isolated from a separate aliquot of blood for (32)P-postlabeling to measure bulky adducts. Single Nucleotide Polymorphisms (SNPs) in phase II enzymes were also monitored in an attempt to identify sensitive receptors. Both total and carcinogenic PAH (cPAH) concentrations were elevated in the parents of case children. Both values were elevated significantly in mothers, whereas only cPAH concentrations were elevated significantly in fathers. Levels of DNA adducts were highly variable and displayed a reverse pattern to that of PAH levels in blood. None of the polymorphisms evaluated were correlated with PAH levels or DNA adducts. For mothers, whose total PAH concentration was above the median concentration, the age-adjusted odds ratio (OR) for having a child with a NTD was 8.7. Although this suggests that PAHs may be a contributing factor to the risk of NTDs, the lack of a correlation with DNA adducts would suggest a possible non-genotoxic mechanism. Alternatively, the PAHs may be a surrogate for a different exposure that is more directly related to the birth defects. The results have shown that blood levels of PAHs may be used to identify populations exposed to elevated concentrations of combustion by-products.