Vitamin C supplementation in pregnancy.
BACKGROUND
Vitamin C supplementation may help reduce the risk of pregnancy complications like pre-eclampsia, intrauterine growth restriction and maternal anaemia. There is a need to evaluate the efficacy and safety of vitamin C supplementation in pregnancy.


OBJECTIVE
To evaluate the effects of vitamin C supplementation, alone or in combination with other separate supplements, on pregnancy outcomes, adverse events, side-effects and use of health resources.


METHODS
We searched the Cochrane Pregnancy and Childbirth Group Trials Register (23 June 2004), Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2004), MEDLINE, Current Contents and EMBASE.


METHODS
All randomised or quasi-randomised controlled trials evaluating vitamin C supplementation in pregnant women. Interventions using a multivitamin supplement containing vitamin C or where the primary supplement was iron were excluded.


METHODS
Two authors independently assessed trials for inclusion, extracted data and assessed trial quality.


RESULTS
Five trials, involving 766 women, are included in this review. No difference was seen between women supplemented with vitamin C alone or combined with other supplements compared with placebo for the risk of stillbirth (relative risk (RR) 0.87, 95% confidence intervals (CI) 0.41 to 1.87, three trials, 539 women), perinatal death (RR 1.16, 95% CI 0.61 to 2.18, two trials, 238 women), birthweight (weighted mean difference (WMD) -139.00 g, 95% CI -517.68 to 239.68, one trial, 100 women) or intrauterine growth restriction (RR 0.72, 95% CI 0.49 to 1.04, two trials, 383 women). Women supplemented with vitamin C alone or combined with other supplements were at increased risk of giving birth preterm (RR 1.38, 95% CI 1.04 to 1.82, three trials, 583 women). Significant heterogeneity was found for neonatal death and pre-eclampsia. No difference was seen between women supplemented with vitamin C combined with other supplements for the risk of neonatal death (RR 1.73, 95% CI 0.25 to 12.12, two trials, 221 women), using a random-effects model. For pre-eclampsia, women supplemented with vitamin C combined with other supplements were at decreased risk when using a fixed-effect model (RR 0.47, 95% CI 0.30 to 0.75, four trials, 710 women); however, this difference could not be demonstrated when using a random-effects model (RR 0.52, 95% CI 0.23 to 1.20, four trials, 710 women).


CONCLUSIONS
The data are too few to say if vitamin C supplementation, alone or combined with other supplements, is beneficial during pregnancy. Preterm birth may have been increased with vitamin C supplementation.
Rumbold
A
A
Department of Obstetrics and Gynaecology, University of Adelaide, Women's and Children's Hospital, 72 King William Road, North Adelaide, SA, Australia, 5006. alice.rumbold@adelaide.edu.au
Crowther
C A
CA
D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000009:adverse effects; D019587:Dietary Supplements / Q000009:adverse effects; D005260:Female; D005313:Fetal Death / Q000517:prevention & control; D006801:Humans; D007231:Infant, Newborn; D011225:Pre-Eclampsia / Q000517:prevention & control; D011247:Pregnancy; D011248:Pregnancy Complications / Q000209:etiology / Q000517:prevention & control*; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000209:etiology / Q000517:prevention & control; D016032:Randomized Controlled Trials as Topic
D001205:Ascorbic Acid