Traffic-related air pollution, preterm birth and term birth weight in the PIAMA birth cohort study

Background

Maternal exposure to air pollution has been associated with adverse pregnancy outcomes. Few studies took into account the spatial and temporal variation of air pollution levels.

Objectives

To evaluate the impact of maternal exposure to traffic-related air pollution during pregnancy on preterm birth and term birth weight using a spatio-temporal exposure model.

Methods

We estimated maternal residential exposure to nitrogen dioxide (NO₂), particulate matter (PM_2.5) and soot during pregnancy (entire pregnancy, 1st trimester, and last month) for 3853 singleton births within the Dutch PIAMA prospective birth cohort study by means of temporally adjusted land-use regression models. Associations between air pollution concentrations and preterm birth and term birth weight were analyzed by means of logistic and linear regression models with and without adjustment for maternal physical, lifestyle, and socio-demographic characteristics.

Results

We found positive, statistically non-significant associations between exposure to soot during entire pregnancy and during the last month of pregnancy and preterm birth [adj. OR (95% CI) per interquartile range increase in exposure 1.08 (0.88–1.34) and 1.09 (0.93–1.27), respectively]. There was no indication of an adverse effect of air pollution exposure on term birth weight.

Conclusions

In this study, maternal exposure to traffic-related air pollution during pregnancy was not associated with term birth weight. There was a tendency towards an increased risk of preterm birth with increasing air pollution exposure, but statistical power was low.     

Exposure to particulate matter and adverse birth outcomes: a comprehensive review and meta-analysis

Increasing number of studies have investigated the impact of maternal exposure to air pollution during pregnancy and adverse birth outcomes, particularly low birth weight (LBW, <2,500?g at birth) and preterm birth (PTB, <37 completed weeks of gestation). We performed a comprehensive review of the peer-reviewed literature and a meta-analysis to quantify the association between maternal exposure to particulate matter with aerodynamic diameter 2.5 and 10???m (PM_2.5 and PM₁₀) during pregnancy and the risk of LBW and PTB. We identified 20 peer-reviewed articles providing quantitative estimate of exposure and outcome that met our selection criteria. There was significant heterogeneity between studies, particularly for findings related to PM₁₀ exposure (LBW, I-squared 54%, p?=?0.01; PTB, I-squared?=?73%, p?<?0.01). Results from random-effect meta-analysis suggested a 9% increase in risk of LBW associated with a 10-??g/m³ increase in PM_2.5 (combined odds ratios (OR), 1.09; 95% confidence interval (CI), 0.90?C1.32), but our 95% CI included the null value. We estimated a 15% increase in risk of PTB for each 10-??g/m³ increase in PM_2.5 (combined OR, 1.15; CI, 1.14?C1.16). The magnitude of risk associated with PM₁₀ exposure was smaller (2% per 10-??g/m³ increase) and similar in size for both LBW and PTB, neither reaching formal statistical significance. We observed no significant publication bias, with p?>?0.05 based on both Begg's and Egger's bias tests. Our results suggest that maternal exposure to PM, particularly PM_2.5 may have adverse effect on birth outcomes. Additional mechanistic studies are needed to understand the underlying mechanisms for this association.     

Residential exposure to outdoor air pollution during pregnancy and anthropometric measures at birth in a multicenter cohort in Spain

Background: A growing body of research suggests that prenatal exposure to air pollution may be harmful to fetal development. We assessed the association between exposure to air pollution during pregnancy and anthropometric measures at birth in four areas within the Spanish Children’s Health and Environment (INMA) mother and child cohort study.Methods: Exposure to ambient nitrogen dioxide (NO₂) and benzene was estimated for the residence of each woman (n = 2,337) for each trimester and for the entire pregnancy. Outcomes included birth weight, length, and head circumference. The association between residential outdoor air pollution exposure and birth outcomes was assessed with linear regression models controlled for potential confounders. We also performed sensitivity analyses for the subset of women who spent more time at home during pregnancy. Finally, we performed a combined analysis with meta-analysis techniques.Results: In the combined analysis, an increase of 10 µg/m³ in NO₂ exposure during pregnancy was associated with a decrease in birth length of –0.9 mm [95% confidence interval (CI), –1.8 to –0.1 mm]. For the subset of women who spent ≥ 15 hr/day at home, the association was stronger (–0.16 mm; 95% CI, –0.27 to –0.04). For this same subset of women, a reduction of 22 g in birth weight was associated with each 10-µg/m³ increase in NO₂ exposure in the second trimester (95% CI, –45.3 to 1.9). We observed no significant relationship between benzene levels and birth outcomes.Conclusions: NO₂ exposure was associated with reductions in both length and weight at birth. This association was clearer for the subset of women who spent more time at home.     

Air pollution exposure during pregnancy, ultrasound measures of fetal growth, and adverse birth outcomes: a prospective cohort study

Background: Air pollution exposure during pregnancy might have trimester-specific effects on fetal growth.Objective: We prospectively evaluated the associations of maternal air pollution exposure with fetal growth characteristics and adverse birth outcomes in 7,772 subjects in the Netherlands.Methods: Particulate matter with an aerodynamic diameter < 10 μm (PM₁₀) and nitrogen dioxide (NO₂) levels were estimated using dispersion modeling at the home address. Fetal head circumference, length, and weight were estimated in each trimester by ultrasound. Information on birth outcomes was obtained from medical records.Results: In cross-sectional analyses, NO₂ levels were inversely associated with fetal femur length in the second and third trimester, and PM₁₀ and NO₂ levels both were associated with smaller fetal head circumference in the third trimester [–0.18 mm, 95% confidence interval (CI): –0.24, –0.12 mm; and –0.12 mm, 95% CI: –0.17, –0.06 mm per 1-μg/m³ increase in PM₁₀ and NO₂, respectively]. Average PM₁₀ and NO₂ levels during pregnancy were not associated with head circumference and length at birth or neonatally, but were inversely associated with birth weight (–3.6 g, 95% CI: –6.7, –0.4 g; and –3.4 g, 95% CI: –6.2, –0.6 g, respectively). Longitudinal analyses showed similar patterns for head circumference and weight, but no associations with length. The third and fourth quartiles of PM₁₀ exposure were associated with preterm birth [odds ratio (OR) = 1.40, 95% CI: 1.03, 1.89; and OR = 1.32; 95% CI: 0.96, 1.79, relative to the first quartile]. The third quartile of PM₁₀ exposure, but not the fourth, was associated with small size for gestational age at birth (SGA) (OR = 1.38; 95% CI: 1.00, 1.90). No consistent associations were observed for NO₂ levels and adverse birth outcomes.Conclusions: Results suggest that maternal air pollution exposure is inversely associated with fetal growth during the second and third trimester and with weight at birth. PM₁₀ exposure was positively associated with preterm birth and SGA.     

A cohort study of traffic-related air pollution impacts on birth outcomes

BACKGROUND: Evidence suggests that air pollution exposure adversely affects pregnancy outcomes. Few studies have examined individual-level intraurban exposure contrasts. OBJECTIVES: We evaluated the impacts of air pollution on small for gestational age (SGA) birth weight, low full-term birth weight (LBW), and preterm birth using spatiotemporal exposure metrics. METHODS: With linked administrative data, we identified 70,249 singleton births (1999-2002) with complete covariate data (sex, ethnicity, parity, birth month and year, income, education) and maternal residential history in Vancouver, British Columbia, Canada. We estimated residential exposures by month of pregnancy using nearest and inverse-distance weighting (IDW) of study area monitors [carbon monoxide, nitrogen dioxide, nitric oxide, ozone, sulfur dioxide, and particulate matter < 2.5 (PM2.5) or < 10 (PM10) microm in aerodynamic diameter], temporally adjusted land use regression (LUR) models (NO, NO2, PM2.5, black carbon), and proximity to major roads. Using logistic regression, we estimated the risk of mean (entire pregnancy, first and last month of pregnancy, first and last 3 months) air pollution concentrations on SGA (< 10th percentile), term LBW (< 2,500 g), and preterm birth. RESULTS: Residence within 50 m of highways was associated with a 26% increase in SGA [95% confidence interval (CI), 1.07-1.49] and an 11% (95% CI, 1.01-1.23) increase in LBW. Exposure to all air pollutants except O3 was associated with SGA, with similar odds ratios (ORs) for LUR and monitoring estimates (e.g., LUR: OR = 1.02; 95% CI, 1.00-1.04; IDW: OR = 1.05; 95% CI, 1.03-1.08 per 10-microg/m3 increase in NO). For preterm births, associations were observed with PM2.5 for births < 37 weeks gestation (and for other pollutants at < 30 weeks). No consistent patterns suggested exposure windows of greater relevance. CONCLUSION: Associations between traffic-related air pollution and birth outcomes were observed in a population-based cohort with relatively low ambient air pollution exposure.     

孕期室外空气污染与早产关系的Meta分析

目的 探讨孕期室外空气污染与早产的关系,为减少早产的发生提供循证医学证据。方法 收集国内外已发表的有关孕期空气污染与早产关系的病例对照研究,采用Stata 12.0软件进行Meta分析。结果 共纳入10篇文献,包括病例48556例,对照548495例。Meta分析显示,整个孕期二氧化氮(NO₂)、PM₁₀、一氧化碳(CO)、PM_2.5、氮氧化物(NO)暴露与早产的合并效应OR值分别为0.960(95%CI:0.935~0.985)、1.068(95%CI:1.035~1.103)、1.122(95%CI:1.078~1.168)、1.110(95%CI:1.043~1.181)、0.994(95%CI:0.973~1.016)。空气污染物NO₂、PM₁₀、二氧化硫(SO₂)暴露时期不同对早产的影响不同,在孕早期暴露其合并效应OR值分别为1.117(95%CI:1.052~1.186)、0.968(95%CI:0.812~1.153)、1.258(95%CI:0.758~2.089);孕中期暴露其合并效应OR值分别为1.000(95%CI:0.982~1.019)、1.127(95%CI:0.896~1.416)、0.977(95%CI:0.711~1.342);孕晚期暴露其合并效应OR值分别为1.006(95%CI:1.002~1.010)、1.053(95%CI:0.973~1.139)、1.003(95%CI:1.000~1.006)。结论 整个孕期暴露于PM₁₀、CO和PM_2.5,孕早期暴露于NO₂,孕晚期暴露于NO₂和SO₂可能与早产的发生有关。     

Work as a street vendor,associated traffic-related air pollution exposures and risk of adverse pregnancy outcomes in Accra,Ghana

BackgroundStreet vending, a dominant occupation in urban areas of developing countries exposes the vendors to several environmental pollutants. We investigated whether work as street vendor impairs foetal growth and shortens gestational duration, and evaluated to what extent exposure to traffic-related air pollution is responsible for these adverse effects.MethodsA cross-sectional study was conducted among mothers and their newborns accessing postnatal services at the Korle Bu Teaching Hospital in Accra, Ghana in 2010, focusing on 105 street vendors and a reference group of 281 mothers. We categorized exposure to traffic-related air pollution on the basis of street vending activity patterns and traffic density in the working area.ResultsMultivariate linear regression analysis adjusting for age, social class, marital status and gravidity of mothers, sex of neonate, and indoor air pollution, indicated a 177 g (95% CI: 324, 31) reduction in birth weight among street vendors. Sensitivity analysis performed by restricting the analysis to term births showed further reductions in birth weight. Generalized linear models adjusting for confounders indicated a 35% (risk ratio (RR) = 1.35; 95% CI: 0.87, 2.12) increased risk of LBW, albeit statistically not significant. LBW risk increased in the sensitivity analysis but was also not statistically significant. The risk of PTB was not associated with street vending (RR = 1.03; 95% CI: 0.67, 1.58). The exposure–response relations observed were not consistent. Moderate activity patterns and high traffic density jointly was associated with a statistically significant 84% (RR = 1.84; 95% CI: 1.05, 3.24) increased risk of LBW.ConclusionStreet vending during pregnancy is a determinant of average foetal growth and risk of LBW. More research is required to further quantify their effects on pregnancy outcomes and safeguard maternal and perinatal health in developing countries.     

Association between Local Traffic-Generated Air Pollution and Preeclampsia and Preterm Delivery in the South Coast Air Basin of California

Background

Preeclampsia is a major complication of pregnancy that can lead to substantial maternal and perinatal morbidity, mortality, and preterm birth. Increasing evidence suggests that air pollution adversely affects pregnancy outcomes. Yet few studies have examined how local traffic-generated emissions affect preeclampsia in addition to preterm birth.

Objectives

We examined effects of residential exposure to local traffic-generated air pollution on preeclampsia and preterm delivery (PTD).

Methods

We identified 81,186 singleton birth records from four hospitals (1997–2006) in Los Angeles and Orange Counties, California (USA). We used a line-source dispersion model (CALINE4) to estimate individual exposure to local traffic-generated nitrogen oxides (NO_x) and particulate matter < 2.5 μm in aerodynamic diameter (PM_2.5) across the entire pregnancy. We used logistic regression to estimate effects of air pollution exposures on preeclampsia, PTD (gestational age < 37 weeks), moderate PTD (MPTD; gestational age < 35 weeks), and very PTD (VPTD; gestational age < 30 weeks).

Results

We observed elevated risks for preeclampsia and preterm birth from maternal exposure to local traffic-generated NO_x and PM_2.5. The risk of preeclampsia increased 33% [odds ratio (OR) = 1.33; 95% confidence interval (CI), 1.18–1.49] and 42% (OR = 1.42; 95% CI, 1.26–1.59) for the highest NO_x and PM_2.5 exposure quartiles, respectively. The risk of VPTD increased 128% (OR = 2.28; 95% CI, 2.15–2.42) and 81% (OR = 1.81; 95% CI, 1.71–1.92) for women in the highest NO_x and PM_2.5 exposure quartiles, respectively.

Conclusion

Exposure to local traffic-generated air pollution during pregnancy increases the risk of preeclampsia and preterm birth in Southern California women. These results provide further evidence that air pollution is associated with adverse reproductive outcomes.     

Early-Life Exposure to Outdoor Air Pollution and Respiratory Health,Ear Infections,and Eczema in Infants from the INMA Study

Background: Prenatal and early-life periods may be critical windows for harmful effects of air pollution on infant health.Objectives: We studied the association of air pollution exposure during pregnancy and the first year of life with respiratory illnesses, ear infections, and eczema during the first 12–18 months of age in a Spanish birth cohort of 2,199 infants.Methods: We obtained parentally reported information on doctor-diagnosed lower respiratory tract infections (LRTI) and parental reports of wheezing, eczema, and ear infections. We estimated individual exposures to nitrogen dioxide (NO₂) and benzene with temporally adjusted land use regression models. We used log-binomial regression models and a combined random-effects meta-analysis to estimate the effects of air pollution exposure on health outcomes across the four study locations.Results: A 10-µg/m³ increase in average NO₂ during pregnancy was associated with LRTI [relative risk (RR) = 1.05; 95% CI: 0.98, 1.12] and ear infections (RR = 1.18; 95% CI: 0.98, 1.41). The RRs for an interquartile range (IQR) increase in NO₂ were 1.08 (95% CI: 0.97, 1.21) for LRTI and 1.31 (95% CI: 0.97, 1.76) for ear infections. Compared with NO₂, the association for an IQR increase in average benzene exposure was similar for LRTI (RR = 1.06; 95% CI: 0.94, 1.19) and slightly lower for ear infections (RR = 1.17; 95% CI: 0.93, 1.46). Associations were slightly stronger among infants whose mothers spent more time at home during pregnancy. Air pollution exposure during the first year was highly correlated with prenatal exposure, so we were unable to discern the relative importance of each exposure period.Conclusions: Our findings support the hypothesis that early-life exposure to ambient air pollution may increase the risk of upper and lower respiratory tract infections in infants.     

Preterm birth and exposure to air pollutants during pregnancy

Background

Research has shown that prenatal exposure to air pollutants may have a detrimental effect on fetal development, with the strength of the relationship depending on the effect being studied. The evidence to date, however, is insufficient to establish a direct causal link between such exposure and preterm delivery. This study evaluates the specific effect of prenatal exposure to NO₂ and benzene on preterm births.

Methods

The population under study comprised 785 pregnant women who formed part of the INMA cohort in Valencia, Spain (2003–2005). Multiple regression models were used for mapping outdoor nitrogen dioxide (NO₂) and benzene levels throughout the area. Individual exposure was assigned as the estimated outdoor levels at each woman’s home measured during each trimester as well as throughout the entire pregnancy. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated in order to assess the association between preterm birth and exposure to NO₂ and benzene. The shape of the exposure–response curve between air pollution and the risk of preterm birth was analyzed with a flexible approach, introducing a natural cubic spline for air pollution levels into the model.

Results

Pregnant women exposed to NO₂ and benzene have an increased risk of preterm birth. This risk was shown to be significant when women were exposed to NO₂ levels >46.2 μg/m³ during the second and third trimesters as well as throughout the entire pregnancy and to benzene levels >2.7 μg/m³ throughout the entire pregnancy.

Conclusion

These results suggest that maternal exposure to traffic-related air pollution is associated with preterm birth.     

Prenatal ambient air pollution exposure and small for gestational age birth in the Puget Sound Air Basin

Several studies have identified high concentrations of air pollution as harmful to the developing fetus, but few studies of traffic-derived air pollution and birth outcomes have been conducted in areas of low to moderate air pollution. We identified singleton live births between 1997 and 2005 (N?=?367,046 births) in the Puget Sound Air Basin of Washington State. We estimated nitrogen dioxide (NO₂) exposure using a land use regression model of traffic, PM_2.5 exposure from the nearest community monitor, and proximity to highways/roadways for the residential location of all subjects. Logistic regression estimates of odds ratios (OR) of small for gestational age (SGA) and low birth weight (<2,500 g) among term births were calculated. We observed a modest association between SGA births with increasing quartile of first trimester NO₂ exposure: second (OR?=?1.01, 95 % confidence interval (CI) 0.97, 1.04), third (OR?=?1.06, 95 % CI 1.03, 1.10), and fourth (OR?=?1.08, 95 % CI 1.04, 1.12) (p trend <0.001). We did not observe an association between PM_2.5 and SGA or low birth weight among term births. Our findings suggest that prenatal exposure to traffic-derived air pollutants has a modest effect on fetal growth in a region with low overall air pollutant concentrations. Given the modest associations, future studies in similar settings that maximize the opportunity to address potential residual confounding are needed.     

Ambient air pollution the risk of stillbirth: A prospective birth cohort study in Wuhan,China

Background

Recent studies suggest that ambient air pollution exposure during pregnancy is associated with stillbirth occurrence. However, the results on the associations between ambient air pollutants and stillbirths are inconsistent and little is known about the gestational timing of sensitive periods for the effects of ambient air pollutants exposure on stillbirth.

Impact of ambient air pollution on birth weight in Sydney, Australia

Background: Studies in Asia, Europe, and the Americas have provided evidence that ambient air pollution may have an adverse effect on birth weight, although results are not consistent. Methods: Average exposure during pregnancy to five common air pollutants was estimated for births in metropolitan Sydney between 1998 and 2000. The effects of pollutant exposure in the first, second, and third trimesters of pregnancy on risk of "small for gestational age" (SGA), and of pollutant exposure during pregnancy on birth weight were examined. Results: There were 138 056 singleton births in Sydney between 1998 and 2000; 9.7% of babies (13 402) were classified as SGA. Air pollution levels in Sydney were found to be quite low. In linear regression models carbon monoxide and nitrogen dioxide concentrations in the second and third trimesters had a statistically significant adverse effect on birth weight. For a 1 part per million increase in mean carbon monoxide levels a reduction of 7 (95% CI –5 to 19) to 29 (95% CI 7 to 51) grams in birth weight was estimated. For a 1 part per billion increase in mean nitrogen dioxide levels a reduction of 1 (95% CI 0 to 2) to 34 (95% CI 24 to 43) grams in birth weight was estimated. Particulate matter (diameter less than ten microns) in the second trimester had a small statistically significant adverse effect on birth weight. For a 1 microgram per cubic metre increase in mean particulate matter levels a reduction of 4 grams (95% CI 3 to 6) in birth weight was estimated. Conclusion: These findings of an association between carbon monoxide, nitrogen dioxide, and particulate matter, and reduction in birth weight should be corroborated by further study.     

Population‐attributable risk of low birthweight related to PM10 pollution in seven Korean cities

Seo J‐H, Leem J‐H, Ha E‐H, Kim O‐J, Kim B‐M, Lee J‐Y, Park H‐S, Kim H‐C, Hong Y‐C, Kim Y‐J. Population‐attributable risk of low birthweight related to PM₁₀ pollution in seven Korean cities. Paediatric and Perinatal Epidemiology 2010; 24: 140–148. To understand the preventable fraction of low birthweight (LBW) deliveries due to maternal exposure to air pollution during pregnancy in Korea, it is important to quantify the population‐attributable risk (PAR). Thus, we investigated the association between maternal exposure to air pollution during pregnancy and LBW, and calculated the PAR for air pollution and LBW in seven Korean cities. We used birth records from the Korean National Birth Register for 2004. A geographic information system and kriging methods were used to construct exposure models. Associations between air pollution and LBW were evaluated using univariable and multivariable logistic regression, and the PAR for LBW due to air pollution was calculated. Of 177 660 full‐term singleton births, 1.4% were LBW. When only spatial variation of air pollution was considered in each city, the adjusted odds ratios unit of particulate matter <10 µm in diameter (PM₁₀) for LBW were 1.08 [95% confidence interval [CI] 0.99, 1.18] in Seoul, 1.24 [95% CI 1.02, 1.52] in Pusan, 1.19 [95% CI 1.04, 1.37] in Daegu, 1.12 [95% CI 0.98, 1.28] in Incheon, 1.22 [95% CI 0.98, 1.52] in Kwangju, 1.05 [95% CI 1.00, 1.11] in Daejeon and 1.19 [95% CI 1.03, 1.38] in Ulsan. The PARs for LBW attributable to maternal PM₁₀ exposure during pregnancy were 7%, 19%, 16%, 11%, 18%, 5% and 16% respectively. Because a large proportion of pregnant women in Korea are exposed to PM₁₀– which is associated with LBW – a substantial proportion of LBW could be prevented in Korea if air pollution was reduced.     

药物及手术流产史与早产关联的出生队列研究

目的 探讨既往药物及手术流产史与早产的关联。方法 参与马鞍山市优生优育队列的3 474名孕妇于孕14周前收集一般人口学资料、既往药物及手术流产史资料,以单胎活产儿3 256人为分析样本。根据是否有药物及手术流产史以及流产次数进行分组,采用logistic回归分析既往药物及手术流产史对随后妊娠早产发生率的影响。结果 早产发生率为4.12%（n=134）,自发性早产发生率为2.49%（n=81）。控制可能的混杂因素后,有过1次药物流产史（RR=2.00,95%CI：1.04～3.85）或2次及以上药物流产史（RR=3.58,95%CI：1.04～12.30）会增加总早产发生风险,药物流产史（RR=2.51,95%CI：1.23～5.15）亦会增加自发性早产风险。有过1次手术流产史（RR=0.67,95%CI：0.42～1.01）或2次及以上手术流产史（RR=0.97,95%CI：0.51～1.85）与总早产或自发性早产（RR=0.72,95%CI：0.43～1.22）关联无统计学意义。结论 既往药物流产史是早产或自发性早产的独立危险因素。     

The association between maternal influenza vaccination during pregnancy and adverse birth outcomes in the United States: Pregnancy risk Assessment Monitoring System (PRAMS)

ObjectiveInfluenza vaccination during pregnancy is highly recommended. We examined the association between maternal influenza vaccination and adverse birth outcomes.MethodsThis cross-sectional study used data from the Pregnancy Risk Assessment Monitoring System (PRAMS) during 2012–2017. The primary exposure was the receipt of influenza vaccination during pregnancy. Low birth weight (LBW), preterm birth (PTB), and small for gestational age (SGA) were the primary outcomes. We conducted multivariable logistic regression models to estimate the adjusted odds ratios (AOR) and 95% confidence intervals (CI). Covariates used to adjust confounding included maternal age, marital status, education, race and ethnicity, insurance status before pregnancy, and smoking status. For a subgroup in 2012–2015, we analyzed the association between influenza vaccination in each trimester and adverse birth outcomes.ResultsDuring 2012–2017, compared with unvaccinated women, women vaccinated during pregnancy had a lower risk of LBW and PTB. During 2012–2015, maternal influenza vaccination in the 1st and 3rd trimesters was associated with a reduced risk of LBW and PTB, and vaccination in the 3rd trimester had a greater protective effect than in the 1st trimester. Influenza vaccination was not associated with SGA regardless of trimester.ConclusionsOur findings suggest that influenza vaccination during pregnancy is a safe and effective way to protect newborns.     

Chronic air pollution exposure during pregnancy and maternal and fetal C-reactive protein levels: the Generation R Study

Background: Exposure to air pollution has been associated with higher C-reactive protein (CRP) levels, suggesting an inflammatory response. Not much is known about this association in pregnancy.Objectives: We investigated the associations of air pollution exposure during pregnancy with maternal and fetal CRP levels in a population-based cohort study in the Netherlands.Methods: Particulate matter (PM) with an aerodynamic diameter ≤ 10 μm (PM₁₀) and nitrogen dioxide (NO₂) levels were estimated at the home address using dispersion modeling for different averaging periods preceding the blood sampling (1 week, 2 weeks, 4 weeks, and total pregnancy). High-sensitivity CRP levels were measured in maternal blood samples in early pregnancy (n = 5,067) and in fetal cord blood samples at birth (n = 4,450).Results: Compared with the lowest quartile, higher PM₁₀ exposure levels for the prior 1 and 2 weeks were associated with elevated maternal CRP levels (> 8 mg/L) in the first trimester [fourth PM₁₀ quartile for the prior week: odds ratio (OR), 1.32; 95% confidence interval (CI): 1.08, 1.61; third PM₁₀ quartile for the prior 2 weeks: OR, 1.28; 95% CI: 1.06, 1.56]; however, no clear dose–response relationships were observed. PM₁₀ and NO₂ exposure levels for 1, 2, and 4 weeks preceding delivery were not consistently associated with fetal CRP levels at delivery. Higher long-term PM₁₀ and NO₂ exposure levels (total pregnancy) were associated with elevated fetal CRP levels (> 1 mg/L) at delivery (fourth quartile PM₁₀: OR, 2.18; 95% CI: 1.08, 4.38; fourth quartile NO₂: OR, 3.42; 95% CI: 1.36, 8.58; p-values for trend < 0.05).Conclusions: Our results suggest that exposure to air pollution during pregnancy may lead to maternal and fetal inflammatory responses.     

Maternal exposure to air pollution and birth outcomes

Background

The knowledge about air pollution effects on birth weight, prematurity, and small for gestational age (SGA) in low-exposure areas is insufficient.

Objectives

The aim of this birth cohort study was to investigate whether low-level exposure to air pollution was associated with prematurity and fetal growth and whether there are sex-specific effects.

Method

We combined high-quality registry information on 81,110 births with individually modeled exposure data at residence for nitrogen oxides (NO_x) and proximity to roads with differing traffic density. The data were analyzed by logistic and linear regression with and without potential confounders.

Results

We observed an increased risk for babies being SGA when we compared highest and lowest NO_x quartiles, adjusting for maternal age, smoking, sex, and year of birth. After additional adjustment for maternal country of origin and parity (which were highly intercorrelated), the increase was no longer statistically significant. However, in subgroup analyses when we compared highest and lowest NO_x quartiles we still observed an increased risk for SGA for girls [odds ratio (OR) = 1.12; 95% confidence interval (CI), 1.01–1.24); we also observed increased risk among mothers who had not changed residency during pregnancy (OR = 1.09; 95% CI, 1.01–1.18). The confounders with the greatest impact on SGA were parity and country of origin. Concerning prematurity, the prevalence was lower in the three higher NO_x exposure quartiles compared with the lowest category.

Conclusion

For future studies on air pollution effects on birth outcomes, careful control of confounding is crucial.     

中国空气污染与不良出生结局的研究进展

目的 对中国空气污染与不良出生结局的相关研究进展进行综述。方法 通过检索万方、中国知网（CNKI）、PubMed、Science Direct、Web of Science等数据库2016年6月30日前发表的中国人群空气污染物暴露与不良出生结局相关文献,按照制定的纳入排除标准进行筛选,并对纳入的27篇文献进行综述。结果 中国孕产妇妊娠期间空气动力学直径≤10 μm的颗粒物（PM₁₀）、二氧化硫（SO₂）、二氧化氮（NO₂）、总悬浮颗粒物（TSP）暴露可能增加低出生体重发病风险;妊娠期间暴露PM₁₀、SO₂、NO₂可能增加早产发病风险;妊娠期间暴露SO₂、NO₂、臭氧（O₃）、PM₁₀可能增加先天性心脏缺陷及其他出生缺陷发病风险。结论 中国孕产妇妊娠期间空气污染物暴露可能增加不良出生结局发病风险,需进一步开展研究探讨其相关性。     

妊娠期肝内胆汁淤积症对早产发生率的影响

目的 探讨妊娠期肝内胆汁淤积症（ICP）对早产发生率的影响。方法 采用前瞻性队列研究,以2014年1月1日至2015年3月31日安庆市立医院所有住院分娩的单胎活产孕妇为研究对象。通过调查问卷和医院电子病历系统,收集孕妇人口学信息等资料,采用单因素和多因素统计方法分析ICP对早产发生率的影响。结果 2 758例孕妇ICP发生率为7.25%,早产发生率为16.28%。ICP增加早产和医源性早产的风险,分别为RR=2.33,95% CI：1.67~3.25和RR=8.46,95% CI：5.45~13.12,但对自发性早产的发生无影响（RR=0.94,95% CI：0.57~1.54）。结论 ICP增加医源性早产的发生风险,与自发性早产的发生无明显相关。