Efficacy of vitamin C supplementation during pregnancy in the prevention of preterm birth: a systematic review and meta-analysis.

2025
Revista brasileira de ginecologia e obstetricia : revista da Federacao Brasileira das Sociedades de Ginecologia e Obstetricia 47
- Ana Gabriela Alves Pereira
- Gabriela Oliveira Gonçalves Molino
- Ana Clara Felix de Farias Santos
- Maírla Marina Ferreira Dias
- Nicole Dos Santos Pimenta
- Nicole Dos Santos Pimenta
- Pedro Henrique Costa Matos da Silva

PubMed: 40584396
DOI: 10.61622/rbgo/2025rbgo1

Study Design

Type: Meta-Analysis
Sample size: n = 567
Population: 17 RCTs (21,567 patients)
Methods: Systematic search in PubMed, Cochrane and Embase; random-effects model meta-analysis

Objective

Preterm birth is a leading global cause of neonatal mortality and morbidity, with oxidative stress playing a role in its pathogenesis. Vitamin C, a powerful antioxidant, may help reduce this risk. This study assessed the effectiveness of vitamin C supplementation, both alone and with vitamin E, in preventing preterm birth compared to a placebo.

Data source

Databases were systematically searched in PubMed, Cochrane and Embase in December 2023 and updated in May 2024.

Study selection

Included RCTs evaluated vitamin C's effect on preterm birth and related neonatal outcomes.

Data collect

Statistical analyses used a random-effects model for pooled risk ratios (RR) and 95% confidence intervals (CI). Heterogeneity was assessed with the I² statistic.

Data synthesis

Seventeen RCTs (21,567 patients) were analyzed. Vitamin C supplementation showed no significant difference compared to placebo for preterm birth (RR 1.04; 95% CI 0.96, 1.14). No significant differences were observed for neonatal death (RR 0.77; 95% CI 0.55, 1.08), NICU admission (RR 1.03; 95% CI 0.95, 1.13), preterm PROM (RR 1.04; 95% CI 0.63, 1.71), or birth weight (MD 52.41; 95% CI -19.65, 124.47). A slight decrease in gestational age was observed (MD 0.26; 95% CI -0.02, 0.55).

Conclusion

Vitamin C supplementation alone or in combination with vitamin E does not significantly prevent preterm birth or improve related neonatal outcomes.

Research Insights

Vitamin C→Increased Birth Weight
No significant differences were observed for ... birth weight (MD 52.41; 95% CI -19.65, 124.47).
Effect
Neutral
Effect size
Small
Vitamin C→Increased Gestational Age
A slight decrease in gestational age was observed (MD 0.26; 95% CI -0.02, 0.55).
Effect
Neutral
Effect size
Small
Vitamin C→Reduced NICU Admission
No significant differences were observed for ... NICU admission (RR 1.03; 95% CI 0.95, 1.13).
Effect
Neutral
Effect size
Small
Vitamin C→Reduced Neonatal Death
No significant differences were observed for neonatal death (RR 0.77; 95% CI 0.55, 1.08).
Effect
Neutral
Effect size
Small
Vitamin C→Reduced Pre-Term Premature Rupture of Membranes
No significant differences were observed for ... preterm PROM (RR 1.04; 95% CI 0.63, 1.71).
Effect
Neutral
Effect size
Small
Vitamin C→Reduced Preterm Births
Vitamin C supplementation showed no significant difference compared to placebo for preterm birth (RR 1.04; 95% CI 0.96, 1.14).
Effect
Neutral
Effect size
Small