空氣汙染與氣喘婦女的早產風險有關


  【24drs.com】根據美國國家衛生研究院的一篇新研究,受孕前、懷孕初期、懷孕後期時曝露於空氣汙染,會使氣喘婦女的早產風險增加。
  
  具體而言,研究者發現,受孕前三個月,氮氧化物之曝露增加30 ppb,與氣喘婦女的早產風險增加將近30%有關,無氣喘婦女的此一風險則是增加8%;同樣的,受孕前一氧化碳之曝露增加,與氣喘婦女的早產風險增加12%有關,而無氣喘之婦女在此因素之風險並無影響。
  
  第一作者、國立Eunice Kennedy Shriver兒童健康與人類發展研究所研究員Pauline Mendola博士在國家衛生研究院的新聞稿中表示,早期的環境曝露情況對於後續的健康有顯著影響。在這個情況下,可能是早期的空氣汙染曝露造成發炎或其他內因性壓力,干擾了胚胎著床及胎盤發育,這些干擾可能會造成早產之發生,進行更多研究將有助於我們更加瞭解空氣汙染對於受孕前後幾個月時的潛在影響。
  
  研究者在3月1日的過敏暨臨床免疫學期刊線上發表他們的研究結果。
  
  美國約有9%的孕齡婦女患有氣喘,這個肺部疾病與懷孕併發症及嬰兒健康問題之風險增加有關。
  
  Mendola博士在新聞稿中解釋,早產是美國一個重要的公衛問題,影響超過十分之一的新生兒。我們的研究發現,空氣汙染會增加氣喘婦女的早產風險,這些研究結果為後續研究奠定基礎,以期為這些有風險者探究預防早產之策略。
  
  研究者蒐集了有關妊娠年齡、孕婦的人口統計數據、醫療、生育與產前史、以及「Consortium on Safe Labor (2002 - 2008)」的分娩與生產總結資訊等資料。「Consortium on Safe Labor」是一項妊娠23週以上者的回溯世代研究,資料來自美國各地的19所醫院的電子病歷。
  
  這個世代包括了233,736名新生兒,其中87%在2005-2007年間出生。排除多胎妊娠和無空氣質量數據者之後,納入分析的樣本包括了204,175名婦女產下的223,502名新生兒,大部份婦女在此研究期間僅懷孕生產一次。
  
  研究者將這些資料和6個空氣汙染物(每個醫院的週遭區域的一氧化碳、氮氧化物、臭氧、空氣動力學直徑小於10微米的顆粒物質、空氣動力學直徑小於2.5微米的顆粒物質、二氧化硫)配對,評估空氣汙染對每一妊娠週齡之早產風險的影響。他們校正的因素包括地點、年齡、種族、懷孕前體重、抽菸與飲酒習慣、孕婦本身的慢性疾病等。
  
  約有11.7%的單胞胎是早產、其中三分之一(33.6%)是極早產或小於妊娠34週。黑人婦女、高齡產婦、單身婦女、有公共保險、懷孕時有抽菸或喝酒、懷孕前有慢性共病症者比較常發生早產;氣喘婦女的早產風險比較高,且初期和整體風險都比較高。
  
  當研究者分析每一妊娠週齡的資料時,他們發現,當氣喘婦女在整個孕期都曝露於汙染物時,風險顯著增加,而某些特定時間點的風險更高。
  
  作者們解釋,不論是妊娠初期(第23、26和29週)和後期(34-36週),氣喘婦女曝露於大部份的空氣汙染物後,早產風險增加。受孕前和懷孕第一週是有關曝露於[一氧化碳、氮氧化物、空氣動力學直徑小於10微米之顆粒物質、空氣動力學直徑小於2.5微米的顆粒物質]之早產風險重要時間點。與[臭氧]有關的風險在懷孕後期比較高,至於沒有氣喘的婦女在整個懷孕期間的曝露情況,極早產風險增加16%、整體早產風險增加8%。
  
  研究者發現,持續和短期曝露於氮氧化物和一氧化碳與風險增加有關,特別是在受孕前和懷孕初期曝露於它們的婦女。
  
  研究者結論表示,空氣汙染物與早產風險增加之關聯是值得關注的,因為氣喘在產科相當常見,而這些曝露情況難以在個人層級管控。
  
  資料來源: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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