Folic-acid linked to fewer pregnancy complications
all pregnancies, may be reduced by multivitamin supplements that
contain folic acid, suggests new study.
The folic acid-containing multivitamin supplements were found to reduce the risk of pre-eclampsia by 63 per cent amongst the 2,951 pregnant women followed for the new study, report Canadian researchers in the American Journal of Obstetrics and Gynecology. "The findings of our study and others give hope of a new prevention strategy for pre-eclampsia, which needs further evaluation," wrote lead author Shi Wu Wen from the University of Ottawa. Pre-eclampsia occurs when a mother's blood pressure rises to the hypertensive range, and excretion of protein in the urine becomes too high. It is estimated to be responsible for about 60,000 deaths worldwide. It is not known why some expectant mothers develop pre-eclampsia, although oxidative stress has been proposed to play a part. The role of antioxidants to reduce oxidative stress had been supported by a small clinical trial that linked vitamin C and E intake to fewer biomarkers for pre-eclampsia for predominantly low-risk participants. However, trials and a recent review of ten trials, five of which were deemed to be high quality, reported that the overall science for vitamins C and E was unconvincing. The new observational study suggests that folic acid supplementation during the second trimester of pregnancy. The researchers collected demographic and clinical data for the women, with only regular daily supplement takes included in this study. Blood samples were taken to determine levels of folate and homocysteine. Wen and co-workers report that supplementation with multivitamins containing folic acid was associated with an average 10.5 micromoles per litre increase in folate levels, an average decrease pf 0.39 micromoles per litre in homocysteine levels, and a 63 per cent reduction in the risk of pre-eclampsia. "We did not observe [however] an association between serum folate or plasma homocysteine level with pre-eclampsia," noted the researchers. "In large-scale epidemiologic studies, it is difficult to tightly control for factors that may affect the measured values of folate or homocysteine." In discussing the mechanism, the researchers stated that there are compelling biologic reasons why folic acid may reduce the risk of pre-eclampsia. "Supplementation of large doses of folic acid in early gestation may work at both stages of pre-eclampsia development," they wrote. "Folic acid, or folate, is one of the B vitamins. It is a coenzyme in the production of nucleic acids and therefore is required by all cells for growth. The placenta develops from a single cell to a complex entity with a weight of about 500 g during pregnancy. An adequate cellular folate supply may play an important role in the implantation and development of the placenta," explained the researchers. "Folate may also reduce the risk of developing pre-eclampsia by improving endothelial function at both placental and systemic levels, directly or indirectly by its effect on lowering blood homocysteine level." Wen and co-workers called for randomised, controlled trials to investigate the link between folic acid supplementation and pre-eclampsia risk and "provide definitive evidence regarding the relationship." "Findings from observational studies such as the current one can help the design of future randomised trials (eg, when the supplementation should be initiated and what dose should be used, etc) and to establish the equipoise for future randomised trials," they concluded. The results add to the well-established benefits of the vitamin that links folate deficiency in early pregnancy to increased risk of neural tube defects (NTD) - most commonly spina bifida and anencephaly - in infants. This connection led to the 1998 introduction of public health measures in the US and Canada, where all grain products are fortified with folic acid - the synthetic, bioavailable form of folate. While preliminary evidence indicates that the measure is having an effect with a reported 15 to 50 per cent reduction in NTD incidence, parallel measures in European countries, including the UK and Ireland, are still on the table. Women of childbearing age are currently recommended a daily dose of 400 micrograms starting before conception. Source: American Journal of Obstetrics and Gynecology January 2008, Volume 198, Issue 1, Pages 45.e1-45.e7 "Folic acid supplementation in early second trimester and the risk of pre-eclampsia" Authors: Shi Wu Wen, X.-K. Chen, M. Rodger, R. Rennicks White, Q. Yang, G.N. Smith, R.J. Sigal, S.L. Perkins, M.C. Walker
