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Zinc supplementation for improving pregnancy and infant outcome

  • Review
  • Intervention




It has been suggested that low serum zinc levels may be associated with suboptimal outcomes of pregnancy such as prolonged labour, atonic postpartum haemorrhage, pregnancy-induced hypertension, preterm labour and post-term pregnancies, although many of these associations have not yet been established.


To assess the effects of zinc supplementation in pregnancy on maternal, fetal, neonatal and infant outcomes.

Search methods

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 September 2011) and reference lists of retrieved studies.

Selection criteria

Randomised trials of zinc supplementation in pregnancy. We excluded quasi-randomised controlled trials.

Data collection and analysis

Three review authors applied the study selection criteria, assessed trial quality and extracted data. When necessary, we contacted study authors for additional information.

Main results

We included 20 randomised controlled trials (RCTs) reported in 51 papers involving over 15,000 women and their babies. Trials were generally at low risk of bias. Zinc supplementation resulted in a small but significant reduction in preterm birth (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.76 to 0.97 in 16 RCTs; 16 trials of 7637 women). This was not accompanied by a similar reduction in numbers of babies with low birthweight (RR 0.93, 95% CI 0.78 to 1.12; 14 trials of 5643 women). No significant differences were seen between the zinc and no zinc groups for any of the other primary maternal or neonatal outcomes, except for induction of labour in a single trial. No differing patterns were evident in the subgroups of women with low versus normal zinc and nutrition levels or in women who complied with their treatment versus those who did not.

Authors' conclusions

The evidence for a 14% relative reduction in preterm birth for zinc compared with placebo was primarily represented by trials involving women of low income and this has some relevance in areas of high perinatal mortality. There was no convincing evidence that zinc supplementation during pregnancy results in other useful and important benefits. Since the preterm association could well reflect poor nutrition, studies to address ways of improving the overall nutritional status of populations in impoverished areas, rather than focusing on micronutrient and or zinc supplementation in isolation, should be an urgent priority.








Cochrane Pregnancy and Childbirth Group's Trials Register(2011年9月30日)および回収した研究の文献リストを検索した。






51件の論文において、15,000名を超える女性とその出生児を対象とした20件のRCTを同定した。試験のバイアスリスクは概ね低かった。亜鉛補充により、早期産について小さいが有意な減少がみられた[リスク比(RR)0.86、95%信頼区間(CI)0.76~0.97、RCT16件、女性7,637名)。低出生体重児数の同様の減少は伴わなかった(RR 0.93、95%CI 0.78~1.12、14試験、女性5,643名)。1件の試験での分娩誘発以外、母体と新生児の他の主要アウトカムのいずれについても、亜鉛群と無亜鉛群とに有意差はなかった。亜鉛と栄養レベルの低い群と正常群とのサブグループ比較、および投与遵守群と非遵守群とのサブグループ比較のいずれにおいても異なるパターンはみられなかった。



Plain language summary

Zinc supplementation for improving pregnancy and infant outcome

Taking zinc during pregnancy helps to slightly reduce preterm births, but does not prevent other problems such as low birthweight babies.

Many women of childbearing age may have mild to moderate zinc deficiency. Low zinc concentrations may cause preterm birth or they may even prolong labour. It is also possible that zinc deficiency may affect infant growth as well. This review of 20 randomised controlled trials, involving over 15,000 women and their babies, found that although zinc supplementation has a small effect on reducing preterm births, it does not help to prevent low birthweight babies compared with not giving zinc supplements before 27 weeks' of pregnancy. No clear differences were seen for development of pregnancy hypertension or pre-eclampsia. The 14% relative reduction in preterm birth for zinc compared with placebo was primarily represented by trials of women with low incomes. In some trials all women were also given iron, folate or vitamins or combinations of these. UNICEF is already promoting antenatal use of multiple-micronutrient supplementation, including zinc, to all pregnant women in developing countries. Finding ways to improve women's overall nutritional status, particularly in low-income areas, will do more to improve the health of mothers and babies than supplementing pregnant women with zinc alone. In low-to-middle income countries, addressing anaemia and infections, such as malaria and hookworm, is also necessary.



妊娠中の亜鉛摂取により早期産が軽度減少するが、低出生体重児などの他の問題は予防されていない。 多くの妊娠可能な女性に、軽度から中等度の亜鉛不足がみられる。亜鉛低値により、早期産や遷延分娩が起こることがある。亜鉛不足により胎児・乳児の発育にも影響する可能性がある。15,000名を超える女性とその出生児を対象とした20件のRCTによる本レビューでは、妊娠27週前の亜鉛補充を受けなかった群に比べて亜鉛補充により早期産減少において小さな効果が得られたが、低出生体重児の予防には有用でなかったという所見が得られた。妊娠高血圧および妊娠高血圧腎症の発症について明らかな差はみられなかった。プラセボに比べて亜鉛による早期産の14%の相対的低下は、低所得国の女性の試験により主として示された。数件の試験では、すべての女性は鉄、葉酸、ビタミンの投与またはそれらの併用を受けていた。UNICEFは亜鉛を含む複数の微量栄養素の出産前補充を、発展途上国のすべての妊婦に対して既に推進している。亜鉛のみの補充を妊婦に勧めるより、特に低所得地域での女性の全体的栄養状態を改善する方法を見出すことの方が母体とその出生児の健康の改善に有用であると考えられる。低~中所得国では、貧血およびマラリアや寄生虫などの感染に対処することも必要である。


監  訳: 江藤 宏美,2012.11.14

実施組織: 厚生労働省委託事業によりMindsが実施した。

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