A randomised, double-blind placebo-controlled trial of ascorbic acid supplementation for the prevention of preterm labour

Abstract

In a previous study from this institution, patients at high risk for preterm labour were screened for the presence of bacterial vaginosis (BV). When BV was present, they were randomised to receive either treatment (metronidazole) or placebo (vitamin C). There were significantly more patients with preterm labour in the metronidazole group. The aim of this double-blind randomised placebo-controlled trial study was to determine whether vitamin C could indeed reduce the recurrence risk of preterm labour. Patients with a history of preterm labour in a preceding pregnancy were randomised to receive 250 mg vitamin C or a matching placebo twice daily until 34 weeks' gestation. They attended a dedicated premature labour clinic. Significantly more women delivered before term in the group that received vitamin C, but there was no difference in the outcome of the babies between the two groups. Supplementation with vitamin C did not prevent premature labour.

The Role of Placental Oxidative Stress and Lipid Peroxidation in Preeclampsia

“…In a systematic review aimed at assessing the benefits of vitamin supplementation in improving various pregnancy outcomes, women who were taking any type of vitamin(s) were less likely to develop preeclampsia than control subjects (relative risk, 0.68; 95% CI, 0.54-0.85) (80). The metaanalysis included four trials comprising 5580 women (77,79,81,82). The risk of preeclampsia significantly decreased after supplementation with vitamins C and E and after multivitamin supplementation.…”

The effects of vitamin C supplementation on pre-eclampsia in Mulago Hospital, Kampala, Uganda: a randomized placebo controlled clinical trial

“…This could be because the women who took supplements developed pre-eclampsia earlier and hence delivered at an earlier gestational age. An earlier study showed that vitamin C supplements given during pregnancy were associated with preterm delivery than controls [46] although this did not translate in poorer neonatal outcomes. However, this was more likely to be a chance finding as more women in this group had a previous history of miscarriage and ante partum haemorrhage.…”

Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function (VCSIP): Rationale, design, and methods of a randomized, controlled trial of vitamin C supplementation in pregnancy for the primary prevention of effects of in utero tobacco smoke exposure on infant lung function and respiratory health

“…A 2005 Cochrane review of vitamin C supplementation in pregnancy concluded that women supplemented with vitamin C were at an increased risk of preterm birth (RR 1.38, 95% CI 1.04 to 1.82, 3 trials, 583 women). 40 This meta-analysis was significantly influenced by one trial, 41 the only trial of the three to demonstrate this pattern of increased preterm deliveries in the treated group. Of note, 43% of the randomized patients were smokers in this study, 41 and there was no significant difference in the incidence of prematurity within the subgroups of smokers by treatment group.…”

“…40 This meta-analysis was significantly influenced by one trial, 41 the only trial of the three to demonstrate this pattern of increased preterm deliveries in the treated group. Of note, 43% of the randomized patients were smokers in this study, 41 and there was no significant difference in the incidence of prematurity within the subgroups of smokers by treatment group. A trial of 10,154 women who were allocated to vitamins C and E in pregnancy versus placebo did not show any significant difference in preterm births.…”