Vitamin C supplementation to prevent premature rupture of the chorioamniotic membranes: a randomized trial.

Randomized controlled trial in pregnant women with singleton pregnancies at about 20 weeks of gestation attending a prenatal clinic in Mexico City. Eligible participants had no acute or chronic disease and were not taking vitamin supplements.

Oral vitamin C, 100 mg once daily as one tablet with water before breakfast, started at 20 weeks of gestation and continued through pregnancy follow-up. The active comparator was placebo.

Vitamin C supplementation reduced premature rupture of the chorioamniotic membranes compared with placebo. PROM occurred in 4 of 52 pregnancies in the vitamin C group versus 14 of 57 in the placebo group, with a relative risk of 0.26 and 95% CI 0.078 to 0.837. Leukocyte vitamin C concentrations increased from 17.26 to 22.17 g/10 8 cells in the supplemented group, while plasma vitamin C declined over time in both groups with no between-group difference. The authors concluded that 100 mg/day vitamin C after 20 weeks of gestation lowers PROM incidence.

The trial was small and conducted at a single prenatal clinic, which limits generalizability. Per-arm randomized sample sizes were not explicitly stated in the source text, and adherence was self-reported rather than objectively verified. Follow-up was limited to pregnancy outcomes, so longer-term maternal and infant effects were not assessed.