Ling Lv

Ambient air pollutant PM10 and risk of preterm birth in Lanzhou, China

IMPORTANCEnExposure to ambient particulate matter during pregnancy has been suggested as a risk factor for preterm birth. However results from limited epidemiologic studies have been inconclusive. Very few studies have been conducted in areas with high air pollution levels.nnnOBJECTIVEnWe investigated the hypothesis that high level exposure to particulate matter with aerodynamic diameter no larger than 10μm (PM10) during pregnancy increases the risk of preterm birth.nnnMETHODSnA birth cohort study was carried out between 2010 and 2012 in Lanzhou, China, including 8969 singleton live births with available information on daily PM10 levels from four monitoring stations, individual exposures during pregnancy were calculated using inverse-distance weighting based on both home and work addresses. Unconditional logistic regression modeling was used to examine the associations between PM10 exposure and risk of preterm birth and its clinical subtypes.nnnRESULTSnIncreased risk of very preterm birth was associated with exposure to PM10 during the last two months of pregnancy (OR, 1.07; 95%CI, 1.02-1.13 per 10μg/m(3) increase for last four weeks before delivery; 1.09; 1.02-1.15 for last six weeks before delivery; 1.10; 1.03-1.17 for last eight weeks before delivery). Compared to the U.S. National Ambient Air Quality Standard (150μg/m(3)), higher exposure level (≥150μg/m(3)) of PM10 during entire pregnancy was associated with an increased risk of preterm birth (1.48; 1.22-1.81) and the association was higher for medically indicated preterm birth (1.80, 1.24-2.62) during entire pregnancy and for very preterm during last 6weeks before delivery (2.03, 1.11-3.72).nnnCONCLUSIONS AND RELEVANCEnOur study supports the hypothesis that exposure to high levels of ambient PM10 increases the risk of preterm birth. Our study also suggests that the risk may vary by clinical subtypes of preterm birth and exposure time windows. Our findings are relevant for health policy makers from China and other regions with high levels of air pollution to facilitate the efforts of reducing air pollution level in order to protect public health.

Body mass index, recreational physical activity and female urinary incontinence in Gansu, China

OBJECTIVEnTo elucidate the influence of recreational physical activity, body mass index (BMI), and waist circumference on the risk of specific types of urinary incontinence.nnnSTUDY DESIGNnWe conducted a population-based cross-sectional survey in Gansu, China among 2603 women aged 20 years or older.nnnRESULTSnThe study found that BMI was positively associated with urinary incontinence (P for trend=0.008) and the association was mainly observed for stress urinary incontinence (OR=1.4, 95% CI: 1.1, 1.9 for BMI=24.0-27.9 kg/m²; OR=2.3, 95% CI: 1.5, 3.6 for BMI ≥ 28.0 kg/m²; P for trend=0.0005). A positive association between stress incontinence (OR=1.7, 95% CI: 1.2, 2.5) and waist circumference was observed for women who had waist circumference between 70 cm and 75 cm compared to waist circumference less than 70 cm. Recreational physical activity was inversely associated with overall and mixed urinary incontinence (P for trend <0.0001 for both). A significant interaction between physical activity and waist circumference was found for overall (P=0.0007) and stress incontinence (P=0.001).nnnCONCLUSIONSnThe findings that physical activity inversely associated with urinary incontinence and its interaction with waist circumference warrant further investigation, particularly in prospective studies.

Folic acid supplementation, dietary folate intake and risk of preterm birth in China.

PurposeFolic acid supplementation has been suggested to reduce the risk of preterm birth. However, results from previous epidemiologic studies have been inconclusive. We investigated the hypothesis that folic acid supplementation and dietary folate intake during pre- and post-conception reduces the risk of preterm birth.MethodsWe analyzed data from a birth cohort study conducted between 2010 and 2012 in Lanzhou, China, including 10,179 pregnant women with live singleton births.ResultsCompared to non-users, folic acid supplement users with >12-week duration had a reduced risk of preterm birth (OR 0.67, 95xa0% CI 0.55–0.83) with a significant dose–response relationship (P for trendxa0=xa00.01). A similar pattern was observed for spontaneous preterm birth. Stronger associations were seen for ever use of folic acid supplement and very preterm birth (OR 0.50, 95xa0% CI 0.36–0.69) and spontaneous very preterm birth (OR 0.42, 95xa0% CI 0.29–0.63). Dietary folate intake during preconception and pregnancy were also associated with reduced risk of preterm birth (OR 0.68, 95xa0% CI 0.56–0.83, OR 0.57, 95xa0% CI 0.47–0.70 for the highest quartiles, respectively), particularly for spontaneous very preterm (OR 0.41, 95xa0% CI 0.24–0.72, OR 0.26, 95xa0% CI 0.15–0.47 for the highest quartiles, respectively). There were also decreased risks of preterm birth observed per 10-µg increase in dietary folate intake, and similar associations were found after stratification by folic acid supplementation status.ConclusionsOur results suggest that folic acid supplementation and higher dietary folate intake during preconception and pregnancy reduces the risk of preterm birth, and the protective effect varies by preterm subtypes.

Exposure to cooking fuels and birth weight in Lanzhou, China: a birth cohort study

BackgroundEarly studies have suggested that biomass cooking fuels were associated with increased risk of low birth weight (LBW). However it is unclear if this reduced birth weight was due to prematurity or intrauterine growth restriction (IUGR).MethodsIn order to understand the relationship between various cooking fuels and risk of LBW and small for gestational age (SGA), we analyzed data from a birth cohort study conducted in Lanzhou, China which included 9,895 singleton live births.ResultsCompared to mothers using gas as cooking fuel, significant reductions in birth weight were observed for mothers using coal (weight differenceu2009=u200973.31xa0g, 95xa0% CI: 26.86, 119.77) and biomass (weight differenceu2009=u200987.84xa0g, 95xa0% CI: 10.76, 164.46). Using biomass as cooking fuel was associated with more than two-fold increased risk of LBW (ORu2009=u20092.51, 95xa0% CI: 1.26, 5.01), and the risk was mainly seen among preterm births (ORu2009=u20093.43, 95xa0% CI: 1.21, 9.74). No significant associations with LBW were observed among mothers using coal or electromagnetic stoves for cooking.ConclusionsThese findings suggest that exposure to biomass during pregnancy is associated with risk of LBW, and the effect of biomass on LBW may be primarily due to prematurity rather than IUGR.

Ambient air pollutant PM10 and risk of pregnancy-induced hypertension in urban China

Background: The relationship between air borne particulate matter ≤10 μm (PM10) exposure and pregnancy-induced hypertension (PIH) is inconclusive. Few studies have been conducted, and fewer were conducted in areas with high levels of PM10. Methods: To examine the association between PM10 and PIH by different exposure time windows during pregnancy, we analyzed data from a birth cohort study conducted in Lanzhou, China including 8 745 pregnant women with available information on air pollution during pregnancy. A total of 333 PIH cases (127 gestational hypertension (GH) and 206 preeclampsia (PE)) were identified. PM10 daily average concentrations of each subject were calculated according to the distance between home/work addresses and monitor stations using an inverse-distance weighting approach. Results: Average PM10 concentration over the duration of entire pregnancy was significantly associated with PIH (OR = 1.12, 95%CI: 1.02, 1.23 per 10 μg m−3 increase), PE (OR = 1.16, 95%CI: 1.03, 1.30 per 10 μg m−3 increase), late onset PE (OR = 1.17, 95% CI: 1.03, 1.32 per10 μg m−3 increase), and severe PE (OR = 1.25, 95% CI: 1.06, 1.48 per 10 μg m−3 increase). Average PM10 during the first 12 gestational weeks was associated with the risk of GH (OR = 1.10, 95% CI: 1.00, 1.21 per 10 μg m−3 increase), and PM10 exposure before 20 gestational weeks was associated with the risk of severe PE (OR = 1.14, 95% CI: 1.01, 1.30 per 10 μg m−3 increase). Conclusions: We found that high level exposure to ambient PM10 during pregnancy was associated with an increased risk of PIH, GH and PE and that the strength of the association varied by timing of exposure during pregnancy.

Pre-pregnancy BMI, gestational weight gain and risk of preeclampsia: a birth cohort study in Lanzhou, China

BackgroundTo evaluate the independent and joint effects of maternal pre-pregnancy BMI and gestational weight gain (GWG) on the risk of preeclampsia and its subtypes.MethodsA birth cohort study was conducted from 2010 to 2012 in Lanzhou, China. Three hundred fourty seven pregnant women with preeclampsia and 9516 normotensive women at Gansu Provincial Maternity and Child Care Hospitalxa0were included in the present study. Unconditional logistic regression models were used to evaluate the associations between pre-pregnancy BMI, GWG, and risk of preeclampsia and its subtypes.ResultsCompared to women with normal pre-pregnancy BMI, those who were overweight/obese had an increased risk of preeclampsia (ORu2009=u20091.81; 95%CI: 1.37–2.39). Women with excessive GWG had an increased risk of preeclampsia (ORu2009=u20092.28; 95%CI: 1.70–3.05) compared to women with adequate GWG. The observed increased risk was similar for mild-, severe- and late-onset preeclampsia. No association was found for early-onset preeclampsia. Overweight/obese women with excessive GWG had the highest risk of developing preeclampsia compared to normal weight women with no excessive weight gain (ORu2009=u20093.78; 95%CI: 2.65–5.41).ConclusionsOur results suggested that pre-pregnancy BMI and GWG are independent risk factors for preeclampsia and that the risk might vary by preeclampsia subtypes. Our study also proposed a potential synergistic effect of pre-pregnancy BMI and GWG that warrants further investigation.

Maternal tea consumption and the risk of preterm delivery in urban China: a birth cohort study

BackgroundStudies investigating the relationship between maternal tea drinking and risk of preterm birth have reached inconsistent results.MethodsThe present study analyzed data from a birth cohort study including 10,179 women who delivered a singleton live birth were conducted in Lanzhou, China between 2010 and 2012.ResultsDrinking tea (ORu2009=u20091.36, 95xa0% CI: 1.09–1.69), and specifically green (ORu2009=u20091.42, 95xa0% CI: 1.08–1.85) or scented tea (ORu2009=u20091.61, 95xa0% CI: 1.04–2.50), was associated with an increased risk of preterm birth. Drinking tea was associated with both moderate preterm (ORu2009=u20091.41, 95xa0% CI: 1.12–1.79) and spontaneous preterm birth (ORu2009=u20091.41, 95xa0% CI: 1.09–1.83). Risk of preterm birth increased with decreasing age of starting tea drinking (<20xa0years, ORu2009=u20091.60, 95xa0% CI: 1.17–2.20) and increasing duration (p for trendu2009<u20090.01). The relationship between tea drinking and preterm birth is modified by both maternal age (pu2009<u20090.05) and gestational weight gain (pu2009<u20090.05).ConclusionsDespite conflicting findings in the previous literature, we saw a significant association with maternal tea drinking and risk of preterm birth in our cohort. More studies are needed both to confirm this finding and to elucidate the mechanism behind this association.

Residential mobility during pregnancy in Urban Gansu, China

Background: Studies on environmental exposures during pregnancy commonly use maternal residence at time of delivery, which may result in exposure misclassification and biased estimates of exposure and disease association. Studies on residential mobility during pregnancy are needed in various populations to aid studies of the environmental exposure and birth outcomes. However, there is still a lack of studies investigating residential mobility patterns in Asian populations. Methods: We analyzed data from 10,542 pregnant women enrolled in a birth cohort study in Lanzhou, China (2010–2012), a major industrial city. Multivariate logistic regression was used to evaluate residential mobility patterns in relation to maternal complications and birth outcomes. Results: Of the participants, 546 (5.2%) moved during pregnancy; among those who moved, 40.5%, 34.8%, and 24.7% moved during the first, second, and third trimester, respectively. Most movers (97.3%) moved once with a mean distance of 3.75km (range: 1–109km). More than half (66.1%) of the movers moved within 3km, 13.9% moved 3–10km, and 20.0% moved >10km. Pregnant women who were >30 years or multiparous, or who had maternal complications were less likely to have moved during pregnancy. In addition, movers were less likely to deliver infants with birth defects, preterm births, and low birth weight. Conclusions: Residential mobility was significantly associated with several maternal characteristics and complications during pregnancy. The study also showed a lower likelihood of adverse birth outcomes among movers than non‐movers, suggesting that moving might be related to reduce exposure to environmental hazards. These results confirm the hypothesis that residential mobility may be important with respect to exposure misclassification and that this misclassification may vary by subpopulations. HIGHLIGHTSLimited studies have investigated residential mobility during pregnancy.The use of maternal residence at delivery as a proxy for environmental exposure may lead to exposure misclassification.Residential mobility was significantly associated with certain maternal characteristics and complications during pregnancy.Mothers who moved during pregnancy were less likely to have infants with birth defects, preterm births, and low birth weight.Residential mobility should be considered in studies that relay on residential address for environmental exposure assessment.

Maternal folic acid supplementation and dietary folate intake and congenital heart defects.

Background It has been reported that folic acid supplementation before and/or during pregnancy could reduce the risk of congenital heart defects (CHDs). However, the results from limited epidemiologic studies have been inconclusive. We investigated the associations between maternal folic acid supplementation, dietary folate intake, and the risk of CHDs. Methods A birth cohort study was conducted in 2010–2012 at the Gansu Provincial Maternity & Child Care Hospital in Lanzhou, China. After exclusion of stillbirths and multiple births, a total of 94 births were identified with congenital heart defects, and 9,993 births without any birth defects. Unconditional logistic regression was used to estimate the associations. Results Compared to non-users, folic acid supplement users before pregnancy had a reduced risk of overall CHDs (OR: 0.42, 95% CI: 0.21–0.86, Ptrend = 0.025) after adjusted for potential confounders. A protective effect was observed for certain subtypes of CHDs (OR: 0.37, 95% CI: 0.16–0.85 for malformation of great arteries; 0.26, 0.10–0.68 for malformation of cardiac septa; 0.34, 0.13–0.93 for Atrial septal defect). A similar protective effect was also seen for multiple CHDs (OR: 0.49, 95% CI: 0.26–0.93, Ptrend = 0.004). Compared with the middle quartiles of dietary folate intake, lower dietary folate intake (<149.88 μg/day) during pregnancy were associated with increased risk of overall CHDs (OR: 1.63, 95% CI: 1.01–2.62) and patent ductus arteriosus (OR: 1.85, 95% CI: 1.03–3.32). Women who were non-user folic acid supplement and lower dietary folate intake have almost 2-fold increased CHDs risk in their offspring. Conclusions Our study suggested that folic acid supplementation before pregnancy was associated with a reduced risk of CHDs, lower dietary folate intake during pregnancy was associated with increased risk. The observed associations varied by CHD subtypes. A synergistic effect of dietary folate intake and folic acid supplementation was also observed.