補充維他命C與E可能無法降低特定懷孕併發症風險


  【24drs.com】April 6, 2010 — 根據一項發表在3月號美國婦科與產科期刊的多中心、隨機分派控制研究結果,產前補充維他命C與E無法降低子癲前症或是妊娠高血壓(GH)機率,但是與流產或是分娩時死亡以及產前膜裂(PPROM)風險更高有關。
  
  加拿大魁北克市蒙特婁大學與Ste-Justine醫院的Hairong Xu醫師與其來自國際抗氧化藥物用於預防子癲前症(INRAPP)研究的同事們寫到,許多證據支持氧化壓力,一種促氧化與抗氧化力量之間的失衡,在發生懷孕高血壓異常上扮演主要角色。我們想要研究產前補充維他命C與E是否可以降低GH發生率,以及GH對高與低風險女性造成的不良病況。
  
  參與者們根據其風險狀態區分,且被隨機分派接受每日補充1 gm的維他命C及400 IU的維他命E或是安慰劑。主要試驗終點為GH與其相關併發症。
  
  在隨機選取的2647位女性中,2363位女性因為試驗提早結束而納入分析,提早結束的原因為發現與補充維他命相關的不良結果。這兩組在發生GF風險與其併發症之間並無差異(相對風險[RR]為0.99;95%信賴區間為0.78-1.26)。然而,補充維他命C及E與非預先定義的流產、分娩時死亡及PPROM風險增加有關。
  
  這項研究的限制包括因為試驗提早結束而降低的統計力量。
  
  試驗作者們寫到,補充維他命C與E並不能降低子癲前症或GH發生率,但卻會增加流產或分娩時死亡,甚至是PPROM的風險。為什麼會造成這個事實的機轉雖然仍不清楚,但有越來越多有關使用這個試驗中使用維他命劑量的擔憂(例如1000 mg的維他命C與400 IU的維他命E[RRR alpha tocopherol]),這個劑量可能增加其他與懷孕有關不良結果的風險,例如新生兒體重過輕與PPROM。因此,根據我們目前所認知,不建議懷孕婦女使用超過上述劑量的維他命C與E用於預防懷孕相關不良結果(包括子癲前症)。
  
  加拿大衛生研究機構贊助這項研究。這項研究作者表示已無相關資金上的往來。

Vitamins C, E Supplementation May Not Reduce Risk for Certain Pregnancy Complications

By Laurie Barclay, MD
Medscape Medical News

April 6, 2010 — Prenatal vitamin C and E supplementation does not reduce the rate of preeclampsia or gestational hypertension (GH) but is associated with greater risk for fetal loss or perinatal death and preterm prelabor rupture of membranes (PPROM), according to the results of a multicenter, randomized controlled trial reported in the March issue of the American Journal of Obstetrics & Gynecology.

"Several lines of evidence support the hypothesis that oxidative stress, an imbalance between prooxidant and antioxidant forces, plays an essential role in the development of hypertensive disorders of pregnancy," write Hairong Xu, MD, MSc, from Hopital Ste-Justine and Universite de Montreal in Quebec City, Canada, and colleagues from the International Trial of Antioxidants in the Prevention of Preeclampsia (INTAPP) study group. "We sought to investigate whether prenatal vitamin C and E supplementation reduces the incidence of ...GH and its adverse conditions among high- and low-risk women."

Participants were stratified by risk status and were randomly assigned to receive daily supplementation with 1 g of vitamin C and 400 IU of vitamin E, or placebo. The main study endpoint was GH and its associated complications.

Among 2647 women randomly selected, data were analyzed for 2363 women because the trial was stopped prematurely when adverse outcomes from supplementation were recognized. The groups did not differ in the risk for GH and its complications (relative risk [RR], 0.99; 95% confidence interval, 0.78 - 1.26). However, vitamin C and E supplementation was associated with nonprespecified outcomes of an increased risk for fetal loss or perinatal death, as well as with PPROM.

Limitations of this study include reduced power because the trial was stopped prematurely.

"Vitamin C and E supplementation did not reduce the rate of preeclampsia or GH, but increased the risk of fetal loss or perinatal death and ...PPROM," the study authors write. "Despite the fact that the underlying mechanisms remain largely unclear, there is increasing concern that supplementation of vitamins C and E at the doses studied [ie, 1000 mg vitamin C and 400 IU vitamin E (RRR alpha-tocopherol)] may increase the risk of other adverse pregnancy outcomes such as low birthweight and PPROM. Therefore, based on our present knowledge, vitamin C and E supplementation at the above doses cannot be recommended for pregnant women to prevent adverse pregnancy outcomes including [preeclampsia]."

The Canadian Institutes of Health Research supported this study. The study authors have disclosed no relevant financial relationships.

Am J Obstet Gynecol. 2010;202:239.e1-239.e10.

    
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