空气污染与气喘妇女的早产风险有关


  【24drs.com】根据美国国家卫生研究院的一篇新研究,受孕前、怀孕初期、怀孕后期时曝露于空气污染,会使气喘妇女的早产风险增加。
  
  具体而言,研究者发现,受孕前三个月,氮氧化物之曝露增加30 ppb,与气喘妇女的早产风险增加将近30%有关,无气喘妇女的此一风险则是增加8%;同样的,受孕前一氧化碳之曝露增加,与气喘妇女的早产风险增加12%有关,而无气喘之妇女在此因素之风险并无影响。
  
  第一作者、国立Eunice Kennedy Shriver儿童健康与人类发展研究所研究员Pauline Mendola博士在国家卫生研究院的新闻稿中表示,早期的环境曝露情况对于后续的健康有显著影响。在这个情况下,可能是早期的空气污染曝露造成发炎或其它内因性压力,干扰了胚胎著床及胎盘发育,这些干扰可能会造成早产之发生,进行更多研究将有助于我们更加了解空气污染对于受孕前后几个月时的潜在影响。
  
  研究者在3月1日的过敏暨临床免疫学期刊在线发表他们的研究结果。
  
  美国约有9%的孕龄妇女患有气喘,这个肺部疾病与怀孕并发症及婴儿健康问题之风险增加有关。
  
  Mendola博士在新闻稿中解释,早产是美国一个重要的公卫问题,影响超过十分之一的新生儿。我们的研究发现,空气污染会增加气喘妇女的早产风险,这些研究结果为后续研究奠定基础,以期为这些有风险者探究预防早产之策略。
  
  研究者搜集了有关妊娠年龄、孕妇的人口统计数据、医疗、生育与产前史、以及「Consortium on Safe Labor (2002 - 2008)」的分娩与生产总结信息等资料。「Consortium on Safe Labor」是一项妊娠23周以上者的回溯世代研究,资料来自美国各地的19所医院的电子病历。
  
  这个世代包括了233,736名新生儿,其中87%在2005-2007年间出生。排除多胎妊娠和无空气质量数据者之后,纳入分析的样本包括了204,175名妇女产下的223,502名新生儿,大部份妇女在此研究期间仅怀孕生产一次。
  
  研究者将这些资料和6个空气污染物(每个医院的周遭区域的一氧化碳、氮氧化物、臭氧、空气动力学直径小于10微米的颗粒物质、空气动力学直径小于2.5微米的颗粒物质、二氧化硫)配对,评估空气污染对每一妊娠周龄之早产风险的影响。他们校正的因素包括地点、年龄、种族、怀孕前体重、抽菸与饮酒习惯、孕妇本身的慢性疾病等。
  
  约有11.7%的单胞胎是早产、其中三分之一(33.6%)是极早产或小于妊娠34周。黑人妇女、高龄产妇、单身妇女、有公共保险、怀孕时有抽菸或喝酒、怀孕前有慢性共病症者比较常发生早产;气喘妇女的早产风险比较高,且初期和整体风险都比较高。
  
  当研究者分析每一妊娠周龄的资料时,他们发现,当气喘妇女在整个孕期都曝露于污染物时,风险显著增加,而某些特定时间点的风险更高。
  
  作者们解释,不论是妊娠初期(第23、26和29周)和后期(34-36周),气喘妇女曝露于大部份的空气污染物后,早产风险增加。受孕前和怀孕第一周是有关曝露于[一氧化碳、氮氧化物、空气动力学直径小于10微米之颗粒物质、空气动力学直径小于2.5微米的颗粒物质]之早产风险重要时间点。与[臭氧]有关的风险在怀孕后期比较高,至于没有气喘的妇女在整个怀孕期间的曝露情况,极早产风险增加16%、整体早产风险增加8%。
  
  研究者发现,持续和短期曝露于氮氧化物和一氧化碳与风险增加有关,特别是在受孕前和怀孕初期曝露于它们的妇女。
  
  研究者结论表示,空气污染物与早产风险增加之关联是值得关注的,因为气喘在产科相当常见,而这些曝露情况难以在个人层级管控。
  
  资料来源:http://www.24drs.com/
  
  Native link:Air Pollution Tied to Preterm Birth Risk for Women With Asthma

Air Pollution Tied to Preterm Birth Risk for Women With Asthma

By Troy Brown, RN
Medscape Medical News

Air pollution exposure before conception, in early pregnancy, and in late pregnancy may increase the risk for preterm birth in women with asthma, according to a new study from the National Institutes of Health.

Specifically, the researchers found that an increased nitrogen oxide exposure of 30 parts per billion in the 3 months before conception was tied to nearly a 30% increase in the risk for preterm birth among women with asthma vs 8% for women without asthma. Similarly, increased carbon monoxide exposure before conception was tied to a 12% increased risk of preterm birth among women with asthma, but showed no effect on the risk among women without asthma.

"Early environmental exposures can have significant effects on later health," Pauline Mendola, PhD, lead author and an investigator at the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, said in a National Institutes of Health news release. "In this case, it may be that early exposure to air pollution sets off inflammation or other internal stresses that interfere with embryo implantation or placental development. Those disruptions could lead to preterm delivery down the road. More research will help us to better understand the potential impact of air pollution in the months surrounding conception."

The researchers published their findings online March 1 in the Journal of Allergy and Clinical Immunology.

Approximately 9% of reproductive-age women in the United States suffer from asthma, a lung disease associated with an increased risk for pregnancy complications and health problems for infants.

"Preterm birth is a major public health problem in this country, affecting more than 1 in 10 infants born in the United States," Dr Mendola explained in the news release. "Our study found that air pollution appears to add to the preterm birth risk faced by women with asthma. These findings set the stage for further studies designed to help prevent preterm birth in this at-risk group."

The researchers collected data on gestational age; maternal demographics; medical, reproductive, and prenatal history; and a summary of labor and delivery information from the Consortium on Safe Labor (2002 - 2008). The Consortium on Safe Labor is a retrospective cohort of births at 23 weeks' gestation or more with data gathered from electronic records from 19 hospitals across the United States.

The cohort included 233,736 newborns, 87% of whom were born between 2005 and 2007. After excluding multifetal pregnancies and those missing air quality data, the analytic sample included 223,502 newborns among 204,175 women. Most of the women in the study contributed only one pregnancy to the cohort.

The researchers matched those data with measures of six air pollutants (carbon monoxide, nitrogen oxides, ozone, particulate matter with an aerodynamic diameter of less than 10 microns, particulate matter with an aerodynamic diameter of less than 2.5 microns, and sulfur dioxide from the areas around each of the hospitals) and assessed the potential effects of air pollution on the risk for preterm birth at each week of gestational age. They adjusted for location, age, race and ethnicity, prepregnancy weight, smoking and alcohol use, and chronic maternal health conditions.

Some 11.7% of singleton births were preterm, and one third (33.6%) of those were early preterm or at less than 34 weeks' gestational age. Preterm birth was more common among black women, those at the extremes of maternal age, single women, those who had public insurance, those who smoked or drank alcohol while pregnant, and women with chronic comorbid conditions before pregnancy. Women with asthma had a higher risk of delivering preterm, both early and overall.

When the researchers analyzed the data for each week of gestation, they found a significantly increased risk for women with asthma when exposed to the pollutants throughout their pregnancies, but certain critical windows were especially risky.

"Women with asthma have higher risks for preterm birth after acute exposure to most criteria air pollutants both early (weeks 23, 26, and 29) and later in gestation (weeks 34-36)," the authors explain. "Preconception and the first weeks of pregnancy appear to be important windows of susceptibility for preterm birth risk with respect to [carbon monoxide, nitrogen oxides, particulate matter with an aerodynamic diameter of less than 10 microns, and particulate matter with an aerodynamic diameter of less than 2.5 microns] exposure. Risks associated with [ozone] appear higher later in gestation and are increased 16% for early preterm and 8% for total preterm in relation to whole pregnancy exposure among women without asthma."

The researchers found an increased risk associated with continued and short-term exposure to nitrogen oxides and carbon monoxide, especially when the women were exposed to them just before conception and during early pregnancy.

"Small increases in preterm birth risk associated with air pollution merit attention given that asthma is common in obstetric population and these exposures are difficult to manage at the individual level," the researchers conclude.

This research was supported by the Intramural Research Program of the National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development. One coauthor has received grants from Laboratoriolaaketieteen edistamissaatio and Paulo Foundation.

J Allergy Clin Immunol. Published online March 1, 2016.

    
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