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Association Between Use of Oral Contraceptives and Folate Status: A Systematic Review and Meta-Analysis

      Abstract

      Objective

      To conduct a systematic review and meta-analysis of the effect of oral contraceptive use on plasma and red blood cell (RBC) folate concentrations.

      Methods

      We searched Medline, EMBASE, Web of Science, and the Cochrane library for human studies published from inception to June 2013 evaluating oral contraceptive use and folate status. Case-control studies, cohort studies, and clinical trials were included. A random-effects model of outcomes was used for the meta-analysis.

      Results

      A total of 2831 women in 17 studies were included in the analysis. In those whose plasma folate concentrations were available, there was a significant folate-lowering effect of oral contraceptives observed (mean reduction 1.27 μg/L; 95% CI 1.85 to 0. 69, P<0.001). Similarly, after analyzing data from 1389 women in 12 studies whose RBC folate concentrations were available, significantly lower folate status was observed among oral contraceptive users (mean reduction 59.32 μg/L; 95% CI 58.03 to 23.04, P<0. 001).

      Conclusion

      Because of the reduction in blood folate concentrations associated with the use of oral contraceptives, it is critical for women of childbearing age to continue folate supplementation during oral contraceptive use.

      Résumé

      Objectif

      Mener une analyse systématique et une méta-analyse quant à l’effet du recours à la contraception orale sur les concentrations plasmatiques et érythrocytaires en folate.

      Méthodes

      Nous avons mené des recherches dans Medline, EMBASE, Web of Science et la Cochrane library en vue d’en tirer les études menées chez l’homme, publiées entre le début de nos travaux et juin 2013, qui ont évalué l’utilisation de contraceptifs oraux et les taux de folate. Les études cas-témoins, les études de cohorte et les essais cliniques ont été admis aux fins de notre analyse. Un modèle à effets aléatoires quant aux issues a été utilisé dans le cadre de la méta-analyse.

      Résultats

      Au total, 2 831 femmes issues de 17 études ont été admises à l’analyse. Chez les femmes pour lesquelles les concentrations plasmatiques en folate étaient disponibles, nous avons constaté que les contraceptifs oraux exerçaient un effet considérable d’atténuation de ces concentrations (baisse moyenne, 1,27 μg/I; IC à 95 %, 1,85 - 0,69, P<0,001). De façon semblable, après avoir analysé les données traitant de 1 389 femmes issues de 12 études pour lesquelles les concentrations érythrocytaires en folate étaient disponibles, nous avons constaté une baisse considérable de ces concentrations chez les utilisatrices de contraceptifs oraux (baisse moyenne, 59,32 μg/I; IC à 95 %, 58,03 - 23,04, P<0,001).

      Conclusion

      En raison de la baisse des concentrations sanguines en folate qui sont associées à l’utilisation de contraceptifs oraux, il est crucial que les femmes en âge de procréer qui ont recours à une telle contraception continuent à prendre une supplémentation en folate.

      Key Words

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