Jan Helge Seglem Mortensen1, Nina Øyen2, Tatiana Fomina3, Mads Melbye4, Steinar Tretli5, Stein Emil Vollset6, Tone Bjørge7. 1. Department of Global Public Health and Primary Care, University of Bergen, Norway; Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway. Electronic address: jan.mortensen@igs.uib.no. 2. Department of Global Public Health and Primary Care, University of Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway. 3. Department of Global Public Health and Primary Care, University of Bergen, Norway. 4. Department of Epidemiology Research, National Health Surveillance and Research, Statens Serum Institut, Copenhagen, Denmark; Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark; Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA. 5. Cancer Registry of Norway, Oslo, Norway. 6. Department of Global Public Health and Primary Care, University of Bergen, Norway; Norwegian Institute of Public Health, Oslo, Norway. 7. Department of Global Public Health and Primary Care, University of Bergen, Norway; Cancer Registry of Norway, Oslo, Norway.
Abstract
BACKGROUND: There is evidence that increased intake of folate protects against the development of several types of cancer. Some studies have, however, raised concern about the safety of folate in relation to cancer risk. Here we examined the risk of maternal cancer after intake of supplemental folic acid in pregnancy. METHODS: This is a population-based cohort study comprising 429,004 women with data from the Medical Birth Registry of Norway, the Cancer Registry of Norway, and other national registries from 1999 to 2010. Altogether 3781 cancer cases were identified during follow-up (average 7 years). Cox proportional hazards regression models were used to estimate hazard ratios of maternal cancer according to folic acid use prior to and during one or two or more pregnancies as compared to no supplement use. RESULTS: Folic acid supplementation use had no overall effect on cancer risk in women using folic acid supplementation in one (HR 1.08; 95% CI 1.00-1.18) or two or more pregnancies (HR 1.06; 95% CI 0.91-1.22) (ptrend=0.12). Analyses of 13 cancer types revealed no associations between folic acid and cancer. CONCLUSION: Folic acid supplementation before and during pregnancy had no overall effect on maternal cancer risk. IMPACT: Folic acid substitution before and/or during pregnancy does not increase the short-term overall maternal cancer risk.
BACKGROUND: There is evidence that increased intake of folate protects against the development of several types of cancer. Some studies have, however, raised concern about the safety of folate in relation to cancer risk. Here we examined the risk of maternal cancer after intake of supplemental folic acid in pregnancy. METHODS: This is a population-based cohort study comprising 429,004 women with data from the Medical Birth Registry of Norway, the Cancer Registry of Norway, and other national registries from 1999 to 2010. Altogether 3781 cancer cases were identified during follow-up (average 7 years). Cox proportional hazards regression models were used to estimate hazard ratios of maternal cancer according to folic acid use prior to and during one or two or more pregnancies as compared to no supplement use. RESULTS:Folic acid supplementation use had no overall effect on cancer risk in women using folic acid supplementation in one (HR 1.08; 95% CI 1.00-1.18) or two or more pregnancies (HR 1.06; 95% CI 0.91-1.22) (ptrend=0.12). Analyses of 13 cancer types revealed no associations between folic acid and cancer. CONCLUSION:Folic acid supplementation before and during pregnancy had no overall effect on maternal cancer risk. IMPACT: Folic acid substitution before and/or during pregnancy does not increase the short-term overall maternal cancer risk.