重點訊息
- 孕期有服用维生素 B 12 補充劑與未服用的女性相比，在孕期或產後的维生素 B 12 營養情况可能有所改善，包括更少的维生素 B 12 缺乏和更高的血液维生素 B 12 濃度，但證據尚不明確。
- 孕期服用维生素 B 12 補充劑對孕婦與其子女的其他健康影響尚不清楚。
公共衛生影響
维生素 B 12 是一種维持人體血液和神經细胞健康的重要營養素。维生素 B 12 缺乏是一個重要的公共衛生問題，特别是對中、低收入國家的孕婦和兒童有著沉重負擔。孕期較低的血液维生素 B 12 濃度與一些不良妊娠結果風險增加有關，例如流產、子宫内的胎兒發育不良、嬰兒的大腦或脊髓有問題 (稱為神經管缺損)，以及嬰兒血液维生素 B 12 濃度較低。
懷孕期間補充維生素 B 12 可能有助於改善婦女及其嬰兒的健康和營養狀況。然而，這一點尚未經過良好的審查，而且維生素 B 12 也不屬於世界衛生組織（WHO；聯合國負責國際公共衛生的專門機構）推薦的女性懷孕期間補充劑的一部分。
我們想從研究中了解什麼？
我們想知道在孕期服用维生素 B 12 補充劑是否會改善婦女及其嬰兒的健康和營養狀況。
我們做了什麼？
我們檢索了關於孕期補充维生素 B 12 的臨床試驗。我們比較並統整這些試驗結果，並根據研究方法與規模等因素，來評估我們對證據的信心。
我們發現了什麼？
我們纳入了 5 項包含 984 名孕婦的試驗。3 項試驗包括 609 名孕婦在内的數據被纳入了分析。孕期服用维生素 B 12 補充劑的女性與未服用相比，在孕期或產後的维生素 B 12 營養情况可能有所改善，包括更少的维生素 B 12 缺乏和較高的血液维生素 B 12 濃度，但證據尚不明確。比較各组孕婦在貧血方面並没有差異。由於可用的結果有限或無法獲得，我們無法評估補充維生素 B 12 對其他結果的影響，例如流產、神經管缺陷和兒童認知（兒童透過思考、理解和感官獲得知識的能力）。
這些數據受到哪些限制？
本次文獻回顧的限制在於研究的數量與規模都很小。並非所有的研究都提供我們感興趣的相關結果數據。我們無法提出確信的結果。
證據的時效性
資料最後更新時間為 2023 年 6 月。
Oral vitamin B 12 supplementation during pregnancy may reduce the risk of maternal vitamin B 12 deficiency and may improve maternal vitamin B 12 concentrations during pregnancy or postpartum compared to placebo or no vitamin B 12 supplementation, but the evidence is very uncertain. The effects of vitamin B 12 supplementation on other primary outcomes assessed in this review were not reported, or were not reported in a format for inclusion in quantitative analyses. Vitamin B 12 supplementation during pregnancy may improve maternal and infant vitamin B 12 status, but the potential impact on longer-term clinical and functional maternal and child health outcomes has not yet been established.
Vitamin B 12 deficiency is a major public health problem worldwide, with the highest burden in elderly people, pregnant women, and young children. Due to its role in DNA synthesis and methylation, folate metabolism, and erythropoiesis, vitamin B 12 supplementation during pregnancy may confer longer-term benefits to maternal and child health outcomes.
To evaluate the benefits and harms of oral vitamin B 12 supplementation during pregnancy on maternal and child health outcomes.
We searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov , the World Health Organization International Clinical Trials Registry Platform ( ICTRP ) on 2 June 2023, and reference lists of retrieved studies.
Randomised controlled trials (RCTs), quasi-RCTs, or cluster-RCTs evaluating the effects of oral vitamin B 12 supplementation compared to placebo or no vitamin B 12 supplementation during pregnancy.
We used standard Cochrane methods. Four review authors independently assessed trial eligibility. Two review authors independently extracted data from included studies and conducted checks for accuracy. Three review authors independently assessed the risk of bias of the included studies using the Cochrane RoB 1 tool. We used GRADE to evaluate the certainty of evidence for primary outcomes.
The review included five trials with 984 pregnant women. All trials were conducted in low- and middle-income countries, including India, Bangladesh, South Africa, and Croatia. At enrolment, 26% to 51% of pregnant women had vitamin B 12 deficiency (less than 150 pmol/L), and the prevalence of anaemia (haemoglobin less than 11.0 g/dL) ranged from 30% to 46%. The dosage of vitamin B 12 supplementation varied from 5 μg/day to 250 μg/day, with administration beginning at 8 to 28 weeks' gestation through to delivery or three months' postpartum, and the duration of supplementation ranged from 8 to 16 weeks to 32 to 38 weeks. Three trials, involving 609 pregnant women, contributed data for meta-analyses of the effects of vitamin B 12 supplementation compared to placebo or no vitamin B 12 supplementation.
Maternal anaemia: there may be little to no difference for maternal anaemia by intervention group, but the evidence is very uncertain (70.9% versus 65.0%; risk ratio (RR) 1.08, 95% confidence interval (CI) 0.93 to 1.26; 2 trials, 284 women; very low-certainty evidence).
Maternal vitamin B 12 status: vitamin B 12 supplementation during pregnancy may reduce the risk of maternal vitamin B 12 deficiency compared to placebo or no vitamin B 12 supplementation, but the evidence is very uncertain (25.9% versus 67.9%; RR 0.38, 95% CI 0.28 to 0.51; 2 trials, 272 women; very low-certainty evidence). Women who received vitamin B 12 supplements during pregnancy may have higher total vitamin B 12 concentrations compared to placebo or no vitamin B 12 supplementation (mean difference (MD) 60.89 pmol/L, 95% CI 40.86 to 80.92; 3 trials, 412 women). However, there was substantial heterogeneity (I 2 = 85%).
Adverse pregnancy outcomes: the evidence is uncertain about the effect on adverse pregnancy outcomes, including preterm birth (RR 0.97, 95% CI 0.55 to 1.74; 2 trials, 340 women; low-certainty evidence), and low birthweight (RR 1.50, 95% CI 0.93 to 2.43; 2 trials, 344 women; low-certainty evidence). Two trials reported data on spontaneous abortion (or miscarriage); however, the trials did not report quantitative data for meta-analysis and there was no clear definition of spontaneous abortion in the study reports. No trials evaluated the effects of vitamin B 12 supplementation during pregnancy on neural tube defects.
Infant vitamin B 12 status: children born to women who received vitamin B 12 supplementation had higher total vitamin B 12 concentrations compared to placebo or no vitamin B 12 supplementation (MD 71.89 pmol/L, 95% CI 20.23 to 123.54; 2 trials, 144 children).
Child cognitive outcomes : three ancillary analyses of one trial reported child cognitive outcomes; however, data were not reported in a format that could be included in quantitative meta-analyses. In one study, maternal vitamin B 12 supplementation did not improve neurodevelopment status (e.g. cognitive, language (receptive and expressive), motor (fine and gross), social-emotional, or adaptive (conceptual, social, practical) domains) in children compared to placebo (9 months, Bayley Scales of Infant and Toddler Development Third Edition (BSID-III); 1 trial; low-certainty evidence) or neurophysiological outcomes (72 months, event-related potential measures; 1 trial; low-certainty evidence), though children born to women who received vitamin B 12 supplementation had improved expressive language domain compared to placebo (30 months, BSID-III; 1 trial; low-certainty evidence).
翻譯者：劉依儒【本翻譯計畫由臺北醫學大學考科藍臺灣研究中心 (Cochrane Taiwan)、東亞考科藍聯盟 (EACA) 統籌執行。聯絡E-mail：cochranetaiwan@tmu.edu.tw】