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Vitamin C Levels in Pregnant Women and Efficacy of Vitamin C Supplements in the Prevention of Preterm Birth: A Systematic Review and Meta-Analysis Cover

Vitamin C Levels in Pregnant Women and Efficacy of Vitamin C Supplements in the Prevention of Preterm Birth: A Systematic Review and Meta-Analysis

Open Access
|Sep 2025

Figures & Tables

Figure 1.

Results of the search and selection process (PRISMA flow diagram)
Results of the search and selection process (PRISMA flow diagram)

Figure 2.

Risk of bias assessment of efficacy studies according to the RoB 2 tool
Risk of bias assessment of efficacy studies according to the RoB 2 tool

Figure 3.

Forest plots showing effect sizes of differences in vitamin C levels between women with preterm birth and controls and effect sizes of efficacy of vitamin C supplementation in prevention of preterm birth
Forest plots showing effect sizes of differences in vitamin C levels between women with preterm birth and controls and effect sizes of efficacy of vitamin C supplementation in prevention of preterm birth

An overview of included studies evaluating efficacy of vitamin C supplementation in prevention of preterm birth

Study ID (first author, year)CountryInclusion criteria regarding gestational age and if previous history of preterm birth was requiredAge of the participants in years (mean±SD, unless otherwise specified)Vitamin C dosage, commencement/duration of supplementationControl, blindingFrequency of preterm birth in vitamin C group (n/N)Frequency of preterm birth in control group (n/N)Study conclusions
1Casanueva et al. 2005 (27)Mexico<20 weeks, no
  • Vitamin C: 27.5±7.4

  • Control: 27.4±7.7

100 mg daily, commenced after 20 weeks of gestation (duration not specified)Placebo, double-blind7/5214/57No significant difference (p=0.142).
2Hajifoghaha et al. 2008 (17)/Haji Foghaha et al. 2009 (16)Iran20 weeks, no
  • Vitamin C: 23.88±4.62

  • Control: 24.00±4.56

100 mg daily, from 20 to 36 weeks of gestationPlacebo, single-blind3/577/60No significant difference (p=0.18).
3Hans et al. 2010 (28)Uganda4 to 12 weeks, no
  • Median (range)

  • Vitamin C: 24 (18–39)

  • Control: 25 (18–37)

400 mg daily (two tablets of 100 mg two times a day), until deliveryNo vitamin C, open-label15/18718/197No significant difference (p=0.719).
4Kiondo et al. 2014 (30)Uganda12–22 weeks, no
  • Age group (%)

  • Vitamin C: ≤19 (19.5)

  • 20–29 (53.0)

  • 30–34 (17.0)

  • ≥35 (10.5)

  • Control: ≤19 (21.0)

  • 20–29 (54.3)

  • 30–34 (14.8)

  • ≥35 (9.9)

1000 mg daily, until deliveryPlacebo, triple-blind47/41551/418No significant difference (p=0.7).
5Steyn et al. 2003 (29)South AfricaBefore 26 weeks, history of previous preterm birth
  • Median (range)

  • Vitamin C: 28 (18–44)

  • Control: 28 (19–45)

500 mg daily (250 mg twice a day), until 34 weeks of gestationPlacebo, double-blind50/10035/100Significantly more preterm birth in vitamin C group compared to control group (p=0.031).

Characteristics of included studies which evaluated vitamin C levels

Study ID (first author, year)CountryBlood sample type, measurement method, time of taking the blood sampleNumber of participantsMean age ± SD in years; Mean gestational age ± SD in weeksMean ± SD of vitamin C levelsConclusionMINORS quality score and category
Preterm birthControlPreterm birthControlPreterm birthControl
1Agil et al. 2008 (9)SpainPlasma, HPLC, at delivery (within 30 minutes)4030NR±NR; NR±NRNR±NR; NR±NR59.33±16.32 μmol/L60.12±9.04 μmol/LComparable levels in both groups.17/24 Moderate
2Al Rashedy et al. 2012 (10)EgyptSerum, HPLC, NS151524.6±3.2; 33.9±1.6 (of neonates)25.5±3.4; 37.2±1.6 (of neonates)23.5±11.2 μmol/mL25.4±10.4 μmol/mLNo significant difference between groups.15/24 Moderate
3Guajardo et al. 1995 (8)USAPlasma, HPLC, at delivery152529.5±4.3; 31.4±3.4 (of neonates)26.2±5.3; 39.6±0.94 (of neonates)1.33±0.62 mg/dL0.72±0.69 mg/dLLevel was significantly higher in the preterm group than in the term group (p<0.05).16/24 Moderate
4Joshi et al. 2008 (7)IndiaPlasma, spectrophotometry, just after delivery4010023.6±3.3; 34.9±1.8 (of neonates)22.1±2.9; 38.9±1.0 (of neonates)257.8±54.1 μmol/L228.0±63.2 μmol/LLevel was significantly higher in the preterm group than in the term group (p=0.01).18/24 Moderate
5Eryürek et al. 1991 (11)TurkeyBlood, spectrophotometry (ascorbate + dehydroascorbate), immediately after the delivery710NR±NR; NR±NRNR±NR; NR±NR6.08±1.75 μg/mL4.91±1.72 μg/mLNo significant difference between groups.14/24 Moderate
DOI: https://doi.org/10.2478/eabr-2025-0010 | Journal eISSN: 2956-2090 | Journal ISSN: 2956-0454
Language: English
Submitted on: Dec 8, 2024
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Accepted on: Jan 21, 2025
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Published on: Sep 14, 2025
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year

© 2025 Ana V. Pejcic, Nemanja Z. Petrovic, Milan D. Djordjic, Milos N. Milosavljevic, published by University of Kragujevac, Faculty of Medical Sciences
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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