EndocrinologyPreconceptional Folic Acid Supplements Are Associated With Reduced Risk Of Premature Birth
Taking folic acid supplements for at least a year before conception is
associated with reduction in the risk of premature birth, according to a
study
by Radek Bukowski (from the University of Texas Medical Branch, United
States of America) and colleagues, published in this week"s PLoS Medicine.
Although most pregnancies last about 40 weeks, many babies (for example
around 12% in the United States) are born before 37 completed weeks of
pregnancy. Babies born prematurely are less likely to survive than
full-term babies and are more likely to have breathing difficulties and
learning or
developmental disabilities. Currently, there are no effective methods of
prevention or treatment of premature (preterm) birth, but previous studies
have suggested that lower concentrations of folate (folic acid) are
associated with shorter duration of pregnancy. Bukowski and colleagues
therefore
tested this idea, by analyzing data collected from a cohort of nearly
35,000 pregnant women.
The results of this study showed that taking folate supplements for at
least one year before conception was associated with a 70% reduction in
spontaneous premature birth between 20 and 28 weeks (a reduction from
0.27% to 0.04%), and a 50% reduction between 28 and 32 weeks (reduction
from
0.38% to 0.18%), as compared to the rate of preterm birth when mothers did
not take additional folate supplementation. Folate supplementation for
less
than a year before conception was not linked to a reduction in the risk of
premature birth in this study, and folate supplementation was not
associated with any other complications of pregnancy.
In a related commentary also published in this week"s PLoS Medicine,
Nicholas Fisk from the University of Brisbane, Australia, and colleagues
(who
were not involved in the original study) say "Methodologically, the study
has several strengths... It is based on a huge dataset, with prospective
recording of dietary supplements and potential confounders, and
gestational age determined accurately on first trimester ultrasound. Those
born
preterm because of intervention were appropriately censored."
Nevertheless, Nicholas Fisk and colleagues also point out limitations to
the study -
for example, this was a secondary analysis of a Down syndrome screening
study, so information on folic acid dose, formulation (with or without
other
supplements), and daily compliance is incomplete. The study design was
observational, so the presence of other factors, such as healthier
behaviors on
the part of women who take folate supplements, may explain the findings.
Further evidence as to whether folic acid prevents spontaneous preterm
birth
will require a randomized controlled trial.
Funding: The FASTER trial on which this study is based was supported by
grant from National Institutes of Health and National Institute of Child
Health and Human Development (RO1 HD 38625).The funders had no role in
study design, data collection and analysis, decision to publish, or
preparation
of the manuscript.
Competing interests: Mary D"Alton (contributing author) has acted as a
consultant for Artemis Health.
Citation:
"Preconceptional Folate Supplementation and the Risk of Spontaneous Preterm Birth: A Cohort Study."
Bukowski R, Malone FD, Porter FT, Nyberg DA, Comstock CH, et al. (2009)
PLoS Med 6(5): e1000061. doi:10.1371/journal.pmed.1000061
PLoS Medicine