Anti-D administration in pregnancy for preventing Rhesus alloimmunisation

 

Abstract

Background

During pregnancy, a Rhesus negative (Rh-negative) woman may develop antibodies when her fetus is Rhesus positive (Rh-positive). These may harm Rh-positive babies.

Objectives

To assess the effects of antenatal anti-D immunoglobulin on the incidence of Rhesus D alloimmunisation when given to Rh-negative women without anti-D antibodies.

Search methods

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2007), and bibliographies.

Selection criteria

Randomised trials in Rh-negative women without anti-D antibodies given anti-D after 28 weeks of pregnancy, compared with no treatment or placebo.

Data collection and analysis

One review author extracted and double-entered data; these were checked by another review author.

Main results

Two average to poor-quality trials, involving over 4500 women, compared anti-D prophylaxis with no treatment. When women received anti-D at 28 and 34 weeks' gestation, relative risk (RR) of immunisation during pregnancy was 0.42 (95% confidence interval (CI) 0.15 to 1.17); after the birth of a Rh-positive infant the RR was 0.42 (95% CI 0.15 to 1.17); and within 12 months after birth of a Rh-positive infant the RR was 0.41 (95% CI 0.16 to 1.04). While none of these differences were statistically significant, the risk difference (RD) between anti-D and no treatment was significant (RD -0.01, 95% CI -0.01 to 0.00) suggesting reduced incidence of immunisation after anti-D prophylaxis.

In the higher dose trial (100 µg; 500 international units (IU) anti-D), there was a nonsignificant reduction in immunisation at two to 12 months following birth of a Rh-positive infant in women who had received anti-D (RR 0.14, 95% CI 0.02 to 1.15). However, women receiving anti-D were significantly less likely to register a positive Kleihauer test (which detects fetal cells in maternal blood) in pregnancy (RR 0.60, 95% CI 0.41 to 0.88) and at the birth of a Rh-positive infant (RR 0.60, 95% CI 0.46 to 0.79). No data were available for the risk of Rhesus D alloimmunisation in a subsequent pregnancy. No differences were seen for neonatal jaundice.

Authors' conclusions

The risk of Rhesus D alloimmunisation during or immediately after a first pregnancy is about 1%. Administration of 100 µg (500 IU) anti-D to women in their first pregnancy can reduce this risk to about 0.2% without, to date, any adverse effects. Although unlikely to confer benefit in the current pregnancy, fewer women may have Rhesus D antibodies in any subsequent pregnancy, but the effects of this needs to be tested in studies of robust design.

 

Plain language summary

Anti-D administration in pregnancy for preventing Rhesus alloimmunisation

Anti-D given during pregnancy at 28 and 34 weeks of pregnancy reduces incidence of antibody formation and probably also reduces immunisation of women.

Women whose blood group is Rh-negative sometimes form Rh-antibodies when carrying a Rh-positive baby. This is more likely during birth, but occasionally happens in late pregnancy. It can cause anaemia, and sometimes death, for a Rh-positive baby in a subsequent pregnancy. Giving the mother anti-D after the first birth does reduce the problems, but giving anti-D during pregnancy is likely to help as well, although more research is required to confirm these possible benefits and identify possible harms.

 

摘要

背景

懷孕期間給予antiD免疫球蛋白來預防Rh同種異體免疫反應(alloimmunisation)

在懷孕期間，Rh陰性的婦女在懷有Rh陽性的胎兒時，身體可能會產生抗體，而這種情形可能會傷害到Rh陽性胎兒。

目標

評估在產前階段，Rh陰性血型而沒有antiD抗體的孕婦在注射antiD免疫球蛋白後，發生RhD同種異體免疫反應的機率。

搜尋策略

我們搜尋Cochrane Pregnancy and Childbirth Group's Trials Register(2007年6月)和相關的參考文獻。

選擇標準

針對沒有antiD抗體的Rh陰性婦女所進行的隨機分組臨床試驗：比較在懷孕28週以後給予antiD治療，與沒有給予治療或僅給予安慰劑處理的效果。

資料收集與分析

一位作者擷取並輸入資料；然後由另一位作者檢視資料的正確性。

主要結論

有兩個試驗(研究品質屬於普通到差等級)，共計有超過4500個婦女參與研究來比較預防性地給予antiD免疫球蛋白與沒有治療的差別。結果發現，孕婦在28到34週之間接受antiD免疫球蛋白注射的話,出現免疫反應的相對危險性(relative risk, RR)在不同階段分別是：在懷孕期間是0.42(95% CI 0.15 – 1.17)；在產下乙名Rh陽性胎兒之後是0.42(95% I 0.15 – 1.17)；在產下Rh陽性胎兒後12個月之內是0.41(95% I 0.16 – 1.04)。雖然這些差異並沒有達到統計學上的意義，然而，有接受antiD免疫球蛋白注射的孕婦與沒有治療者之間發生免疫反應的危險性差異值(risk difference, RD)卻是有統計上顯著的意義。(RD −0.01, 95% CI −0.01 – 0.00)。這暗示預防性地給予antiD 免疫球蛋白注射可以降低Rh免疫反應的發生。 在給予高劑量的試驗裡(100 微克；50 國際單位antiD)，接受antiD治療的婦女在生下Rh陽性胎兒的2到12個月間發生Rh免疫反應的相對危險性是0.14(95% CI 0.02 – 1.15)，並沒有達到統計上的意義。然而，有接受antiD治療的婦女在懷孕期間(RR 0.60, 95% CI 0.41 – 0.88)及產下Rh陽性胎兒時(RR 0.60, 95% CI 0.46 – 0.79)，Kleihaur test(在母血內偵測胎兒細胞的一種檢驗方法)呈現陽性結果的機率卻有意義的下降。沒有資料可供分析下一次懷孕時發生Rhesus D 同種異體免疫反應的危險性究竟如何。另外，在新生兒黃疸的發生上，有沒有接受antiD治療也沒有差異。

作者結論

Rh陰性血型的孕婦在第一次懷孕期間或懷孕剛結束時，發生Rh D同種異體免疫反應的危險性大約是1% 。如果這些婦女在她們第一次懷孕期間接受100 微克(50 國際單位)的antiD注射的話，那麼這個危險性將會降低到0.2% ，而且截至目前為止，沒有出現任何不良的副作用。雖然注射antiD對這次懷孕似乎沒有立即的好處，但是卻會使較少的婦女在下次懷孕期間出現RhD的抗體。儘管如此，我們還需要更多設計良好的試驗來驗證這個效應。

翻譯人

本摘要由周產期醫學會(Taiwan Society of Perinatology)洪泰和翻譯。

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

總結

在懷孕28到34週之間給予antiD免疫球蛋白的注射可以降低antiD抗體形成的機會，或許進而減少孕婦發生Rh D免疫反應。Rh陰性血型的婦女，當懷有Rh陽性血型的胎兒時，有時候體內會產生Rh抗體。這個現象多半發生在生產的時候，但是偶而也會發生在懷孕末期。當這個孕婦再一次懷有Rh陽性胎兒時，這些抗體會造成胎兒貧血，甚至死亡。在這些Rh陰性血型的母親生完第一個孩子後，給予antiD注射的確可以減少這個問題的發生。至於在懷孕期間給予antiD注射，似乎也有同樣的助益。然而，我們還需要更多的研究來證實它的可能好處以及發現可能的傷害。