Exposure to tobacco smoke and stillbirth: a national prospective cohort study in rural China.

INTRODUCTION: Parental exposure to tobacco smoke has been associated with an increased risk of stillbirth, while only a few studies took the overall parental tobacco exposure status into consideration. We aim to explore the relationship of parental smoking and passive smoking before and during pregnancy with stillbirth in a large Chinese rural cohort. DESIGN: 248 501 couples were enrolled in a national prospective cohort study conducted in rural China. Parental exposure to tobacco smoke before and during pregnancy, along with other risk factors, was ascertained by questionnaires. Pregnancy outcomes were recorded by physicians. RESULTS: The ORs (Odds Ratios) of maternal active smoking, maternal passive smoking, paternal active smoking and paternal passive smoking were 2.07 (95% CI 1.25 to 3.41), 1.22 (95% CI 1.01 to 1.47), 1.36 (95% CI 1.13 to 1.63) and 1.10 (95% CI 0.87 to 1.39), respectively. The rates of stillbirth increased from 0.31% for the maternal non-smoking group to 0.43% for the smoking cessation during pregnancy group, to 0.64% for the decreased smoking group and 1.28% for the continuing smoking group. A similar pattern was found in the change in paternal smoking status and stillbirth. Stratified by maternal passive smoking, the OR of paternal smoking was 1.35 (95% CI 1.13 to 1.61) in the maternal non-smoking group and 1.67 (95% CI 1.09 to 2.56) in the maternal passive smoking group. CONCLUSIONS: Parental exposure to tobacco smoke increased the risk of stillbirth, especially for those continuing smoking during pregnancy. Paternal smoking is an independent risk factor for stillbirth despite maternal passive smoking status.

Risk factors of stillbirth in rural China: A national cohort study.

People living in rural China are more frequently exposed to some specific risk factors which made stillbirth rate higher than urban areas. National Free Preconception Health Examination Project was launched to investigate these risk factors and collected a representative sample of 248501 participants from 31 provinces in China from 2010 to 2013. Parental risk factors were ascertained twice before and during pregnancy respectively by questionnaires. Stillbirth or live birth were recorded by trained physicians. In the analysis, nested case-control study was conducted, and propensity score matching method was used to adjust the confounding. Multi-level logistic regression was used to fit for multi-level sampling. The overall stillbirth rate was 0.35% in rural China, it was higher in North (0.42%) and West (0.64%) areas. Maternal exposure to pesticide (OR (95%CI 1.06, 3.39)), hypertension (OR = 1.58 (95%CI 1.07, 2.34)), lack of appetite for vegetables (OR = 1.99 (95%CI 1.00, 3.93)), stress (compared with no pressure, OR of a little pressure was 1.34(95% CI 1.02, 1.76)); paternal exposure to smoking (OR = 1.22 (95% CI 1.02, 1.46)), organic solvents (OR = 1.64 (95% CI 1.01, 2.69)) were found independent risk factors of stillbirth. Folacin intake 3 months before pregnancy (OR = 0.72 (95%) CI 0.59, 0.89), folacin intake 1-2 months before pregnancy (OR = 0.71 (95% CI 0.55, 0.92)), folacin intake after pregnancy (OR = 0.81 (95% CI 0.65, 1.02) for) were protect factors of stillbirth. Maternal pesticide exposure, lack of vegetables, stress, paternal smoking and exposure to organic solvents were risk factors of stillbirth. Folic acid intake was protective factor of stillbirth, no matter when the intake began.

Both maternal and paternal risk factors for term singleton low birthweight infants in rural Chinese population: a population-based, retrospective cohort study.

No large population-based study has focused on both maternal paternal risk factors for low birthweight (LBW) in China. We aimed to identify parental risk factors associated with LBW.A population-based, retrospective cohort study was conducted on 202,725 singleton infants at 37-42 weeks. These term singleton newborns were classified as LBW with birthweight ≤2500 g(TLBW) and normal birthweight between 50th to 97th percentile (TNBW 50th-97th) according to Chinese singleton norms. Multiple logistic regression analyses were used to find those parental risk factors of LBW by comparing two groups. TLBW and TNBW(50th-97th) occupied 4.8% and 70.8% of the study population, respectively. Logistic regression showed a significant association with positive maternal hepatitis B surface antigen (RR = 1.979, P = 0.047), irregular folic acid intake (RR = 1.152, P = 0.003), paternal history of varicocele (RR = 2.404, P = 0.003) and female babies (RR = 1.072, P = 0.046). Maternal smoking, hypertension and history of stillbirth were found related to LBW but no statistically significant. Positive maternal hepatitis B surface antigen, irregular folic acid intake, paternal history of varicocele had a negative effect on birth weight. Measures are necessarily taken to avoid them to improve pregnancy outcomes. Further studies should be done to investigate each detailed risk factors on LBW.

Paternal exposure to medical-related radiation associated with low birthweight infants: A large population-based, retrospective cohort study in rural China.

Low birthweight (LBW) is closely associated with fetal and perinatal mortality and morbidity. We identified the risk factors of LBW and geographical differences in LBW incidence in 30 Chinese provinces in the present study.This study was a population-based, retrospective cohort study performed in 30 Chinese provinces. We used data from the free National Pre-pregnancy Checkups Project, which is a countrywide population-based retrospective cohort study. To identify regional differences in LBW incidence, we used the Qinling-Huaihe climate line to divide China into northern and southern sections and the Heihe-Tengchong economic line to divide it into eastern and western sections. Multivariate unconditional logistic regression analysis with SAS 9.4 was used for data analysis. P < .05 was considered statistically significant.LBW incidence was 4.54% in rural China. Southern China had a significantly higher incidence (4.65%) than northern China (4.28%). Our main risk factor for LBW is paternal exposure to radiation (odds ratio = 1.537), which has never been studied before.This study identifies multiple risk factors of couples giving birth to LBW babies including paternal risk factors.

Correlation between preconception maternal non-occupational exposure to interior decoration or oil paint odour and average birth weight of neonates: findings from a nationwide cohort study in China's rural areas.

BACKGROUND: Birth weight is a critical indicator of neonatal health and foretells people's health in adolescence and even adulthood. Some researchers have warned against the adverse effects on babies' birth weight of exposure to pollutants in interior decoration or oil paint by odour intake. This study evaluated the effects of maternal exposure to such factors before conception on the birth weights of neonates. METHODS: Data on 213 461 cases in this study were from the database of the free National Pre-pregnancy Checkups Project. Defined as 'exposed' were those women exposed to oil paint odour or interior decoration at home or in the workplace within 6 months before their pregnancy. The study focused on revealing the correlation between such exposure and the birth weight of the neonates of these women, especially the incidence of macrosomia and low birth weight (LBW). Statistical analysis was conducted using the Kruskal-Wallis H test, the Mann-Whitney U test and logistic regression. RESULTS: The birth weight of babies from mothers non-occupationally exposed to such settings averaged 3465 g (range 3150-3650 g), whereas the birth weight of those from mothers free of such exposure averaged 3300 g (range 3000-3600g). Maternal exposure preconception to interior decoration or oil paint odour reduced the incidence of LBW in their babies (p=0.003, OR 0.749, 95% CI 0.617 to 0.909). Such exposure may also augment the probability of macrosomia (p<0.001, OR 1.297, 95% CI 1.133 to 1.484). CONCLUSION: Maternal exposure to interior decoration or oil paint odour preconception may increase the average birth weight of neonates, as well as the incidence of macrosomia.