title: Vitamin C supplementation to prevent premature rupture of the chorioamniotic membranes: a randomized trial.
abstract: BACKGROUND
  Vitamin C is involved in the synthesis and degradation of collagen and is important for maintenance of the chorioamniotic membranes. Inadequate availability of ascorbic acid during pregnancy has been proposed as a risk factor for premature rupture of the chorioamniotic membranes (PROM).
  
  
  OBJECTIVE
  The objective of the study was to evaluate the effectiveness of 100 mg vitamin C/d in preventing PROM.
  
  
  METHODS
  A controlled double-blind trial was performed. Pregnant women (n = 126) in their 20th wk of gestation were invited; 120 accepted and were randomly assigned to 2 groups (100 mg vitamin C/d or placebo). Every 4 wk, plasma and leukocyte vitamin C concentrations were measured, and each subject was evaluated for cervicovaginal infection. The incidence of PROM was recorded for each group as an indicator of the protective effect of vitamin C supplementation.
  
  
  RESULTS
  One hundred nine patients finished the study. Mean plasma vitamin C concentrations decreased significantly throughout the pregnancy in both groups (P = 0.001), and there were no significant differences between groups. Between weeks 20 and 36, mean leukocyte vitamin C concentrations decreased from 17.5 to 15.23 microg/10(8) cells in the placebo group and increased from 17.26 to 22.17 microg/10(8) cells in the supplemented group (within- and between-group differences: P = 0.001). The incidence of PROM was 14 per 57 pregnancies (24.5%) in the placebo group and 4 per 52 pregnancies (7.69%) in the supplemented group (relative risk: 0.26; 95% CI: 0.078, 0.837).
  
  
  CONCLUSIONS
  Daily supplementation with 100 mg vitamin C after 20 wk of gestation effectively lessens the incidence of PROM.
authors.affiliation: Public Health Research Branch, National Institute of Perinatology, Mexico City, Mexico. casanuev@servidor.unam.mx
authors.forename: Esther
authors.initials: E
authors.lastname: Casanueva
authors.forename: Carmina
authors.initials: C
authors.lastname: Ripoll
authors.forename: Maricruz
authors.initials: M
authors.lastname: Tolentino
authors.forename: Rosa Maria
authors.initials: RM
authors.lastname: Morales
authors.forename: Frania
authors.initials: F
authors.lastname: Pfeffer
authors.forename: Pablo
authors.initials: P
authors.lastname: Vilchis
authors.forename: Felipe
authors.initials: F
authors.lastname: Vadillo-Ortega
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism / Q000627:therapeutic use*; D001205:Ascorbic Acid / Q000097:blood / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000453:epidemiology / Q000517:prevention & control*; D006801:Humans; D008800:Mexico / Q000453:epidemiology; D011247:Pregnancy
chemical_list: D000975:Antioxidants; D001205:Ascorbic Acid