Antioxidants for preventing pre-eclampsia

  • Review
  • Intervention

Authors


Abstract

Background

Oxidative stress has been proposed as a key factor involved in the development of pre-eclampsia. Supplementing women with antioxidants during pregnancy may help to counteract oxidative stress and thereby prevent or delay the onset of pre-eclampsia.

Objectives

To determine the effectiveness and safety of any antioxidant supplementation during pregnancy and the risk of developing pre-eclampsia and its related complications.

Search methods

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2007), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2006, Issue 3), MEDLINE (1950 to October 2007) and Current Contents (1998 to August 2004).

Selection criteria

All randomised trials comparing one or more antioxidants with either placebo or no antioxidants during pregnancy for the prevention of pre-eclampsia, and trials comparing one or more antioxidants with another, or with other interventions.

Data collection and analysis

Two review authors independently assessed trials for inclusion and trial quality and extracted data.

Main results

Ten trials, involving 6533 women, were included in this review, five trials were rated high quality. For the majority of trials, the antioxidant assessed was combined vitamin C and E therapy. There was no significant difference between antioxidant and control groups for the relative risk (RR) of pre-eclampsia (RR 0.73, 95% confidence intervals (CI) 0.51 to 1.06; nine trials, 5446 women) or any other primary outcome: severe pre-eclampsia (RR 1.25, 95% CI 0.89 to 1.76; two trials, 2495 women), preterm birth (before 37 weeks) (RR 1.10, 95% CI 0.99 to 1.22; five trials, 5198 women), small-for-gestational-age infants (RR 0.83, 95% CI 0.62 to 1.11; five trials, 5271 babies) or any baby death (RR 1.12, 95% CI 0.81 to 1.53; four trials, 5144 babies). Women allocated antioxidants were more likely to self-report abdominal pain late in pregnancy (RR 1.61, 95% CI 1.11 to 2.34; one trial, 1745 women), require antihypertensive therapy (RR 1.77, 95% CI 1.22 to 2.57; two trials, 4272 women) and require an antenatal hospital admission for hypertension (RR 1.54, 95% CI 1.00 to 2.39; one trial, 1877 women). However, for the latter two outcomes, this was not clearly reflected in an increase in any other hypertensive complications.

Authors' conclusions

Evidence from this review does not support routine antioxidant supplementation during pregnancy to reduce the risk of pre-eclampsia and other serious complications in pregnancy.

摘要

背景

抗氧化劑預防子癇前症

氧化壓力已被提出來是演變成子癇前症的一個關鍵因素。在懷孕期間補充抗氧化劑的孕婦可能有助於抵消氧化壓力,從而預防或延緩子癇前症的發生。

目標

要確定在懷孕期間補充抗氧化劑的有效性和安全性,與演變成子癇前症的風險及相關的併發症。

搜尋策略

我們檢索了Cochrane資料庫中妊娠組和分娩組試驗註冊登記(2007年5月),Cochrane控制試驗的中央登記註冊(Cochrane圖書館2006年第3期),MEDLINE(1950年至2007年10月)和Current Contents(1998年至2004年8月)。

選擇標準

所有的隨機試驗比較了在懷孕期間使用一個或多個抗氧化劑,與安慰劑或沒有使用抗氧化劑以預防子癇前症。隨機試驗也在使用一個或多個抗氧化劑與其他方法之間,或與其他介入性治療之間作比較。

資料收集與分析

兩個審查作者獨立地評估納入的試驗和試驗的品質與取得的數據。

主要結論

10項試驗,包括6533名孕婦,被納入本次審查,其中5項試驗被評為優質試驗。在多數的試驗中,評估使用抗氧化劑與維生素C和維生素E的結合性治療。抗氧化劑組和對照組的子癇前症的相對危險度(RR)(RR是0.73,95%confidence intervals(CI)是0.51至1.06;9項試驗,5446名孕婦)或任何其他主要預後,並無顯著差異:重度子癇前症(RR是1.25,95%CI是0.89~1.76,2項試驗,2495名孕婦),早產(妊娠37週前)(RR是1.10,95%CI是0.99至1.22;5項試驗,5198名孕婦),小於妊娠週數的胎兒(RR是0.83,95%CI是0.62至1.11;5項試驗,5271名胎兒)或胎兒死亡(RR是1.12,95%CI是0.81~1.53;4項試驗,5144名胎兒)。被分配抗氧化劑組的孕婦,在懷孕後期更有可能會自我報告腹痛(RR是1.61,95%CI是1.11至2.34;1項試驗,1745名孕婦),需要降高血壓藥物治療(RR是1.77,95%CI是1.22至2.57,2項試驗,4272名婦女),因高血壓被要求產前入院(RR是1.54,95%CI是1.00至2.39;1項試驗,1877名孕婦)。但是後兩者的結果,並沒有明顯地反映在任何其他高血壓併發症的增加上面。

作者結論

從這個審查中,證據並不支持在懷孕期間常規補充抗氧化劑,以減少子癇前症和其他嚴重妊娠併發症的風險。

翻譯人

本摘要由周產期醫學會(Taiwan Society of Perinatology)陳光昭翻譯。

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

抗氧化劑用於預防子癇前症。在懷孕期間子癇前症發生時,婦女有高血壓及蛋白尿。在某些情況下,它會導致胎兒生長遲緩和早產。某些孕婦也可能有嚴重併發症,有時會影響肝臟,腎臟,腦或凝血系統,增加母親和嬰兒的死亡風險。存在過量的化學物質,所謂的‘自由基’,可能是一個演變成子癇前症的因素。抗氧化劑如維生素C,維生素E,硒和番茄紅素(lycopene),能中和自由基。這次審查包括10項試驗,6533名孕婦,並檢視幾種抗氧化劑。總體來說,審查發現使用補充抗氧化劑不會減少子癇前症,高血壓或早產。當抗氧化劑被分開進行評估時,除了維生素C和維生素E外,沒有足夠的數據可以清楚顯示使用抗氧化劑是否有任何好處。現有的證據並不支持使用抗氧化劑,以減少子癇前症或其他妊娠併發症的風險,但也有試驗仍在進行中。

Plain language summary

Antioxidants for preventing pre-eclampsia

Pre-eclampsia can occur during pregnancy when women have high blood pressure and protein in their urine. In some cases, it can lead to poor growth for the baby and premature birth. There can also be serious complications for the woman, sometimes affecting the liver, kidneys, brain or blood clotting system. Both mother and baby are at risk of mortality. A possible contributing factor to the development of pre-eclampsia may be the presence of excessive amounts of chemicals called 'free radicals'. Antioxidants, such as vitamin C, vitamin E, selenium and lycopene, can neutralize free radicals. The review covered 10 trials, involving 6533 women, and looked at several antioxidants. Overall the review found no reduction in pre-eclampsia, high blood pressure or preterm birth with the use of antioxidant supplements. When antioxidants were assessed separately, there were insufficient data to be clear about whether there was any benefit or not, except for vitamin C and E. The current evidence does not support the use of antioxidants to reduce the risk of pre-eclampsia or other complications in pregnancy, but there are trials still in progress.

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