Folic acid before pregnancy reduces SGA babies
Taking folic acid before conception significantly reduces the risk of small for gestational age (SGA) babies at birth.
This United Kingdom (UK) population-based study is published in An International Journal of Obstetrics and Gynaecology (BJOG). The study assesses the affects of taking folic acid supplements before and during pregnancy to evaluate the risk to a baby being SGA at birth. Small for gestational age (SGA) babies are defined as having a birth weight in the lowest 10% of babies born.
Being small for gestational age is associated with increased neonatal morbidity and an increased risk of chronic disease in later life such as diabetes, hypertension, obesity, cardiovascular disease and mental health problems.
Folic acid supplements have already been shown to reduce the risk of neural tube defects, such as spina bifida, and is recommended in the UK for women prior to conception.
However, uptake is low in women of child bearing age state the authors, and previous studies have suggested pre-conception use is between 14.8% and 31%, with lower use in younger ages and in ethnic minorities.
The total study population represented a diverse group of women, mean age at pregnancy of 28.7 years, a median BMI of 24.7 and 42% being first time mothers. The majority of women were non-smokers (81.7%).
Of 108,525 pregnancies with information on folic acid supplements, 84.9% had taken folic acid during pregnancy. Commencing the supplement was recorded in 39,416 pregnancies, of which 25.5% of women took it before conception.
Results show that the overall proportion of babies with a birth weight under the 10th percentile was 13.4% and under the 5th percentile was 7%. The highest rate of SGA births occurred in pregnancies where no folate was taken, with 16.3% under the 10th percentile and 8.9% under the 5th percentile.
In pre-conceptile women the prevalence of birth weight lower than the 10th percentile was 9.9% while that of birth weight under the 5th centile was 4.8%.
And in women taking folic acid post-conceptually, birth weight lower than the 10th percentile was 13.8%, while that of birth weight under the 5th centile was 7.1%.
The authors conclude that although folic acid supplements are a standard recommendation in the UK, the policy is poorly followed and strategies are needed to increase uptake. Further research is needed to find out how folic acid supplements produce such a positive result on birth weight and how much the dose of supplements can be increased in women at high risk of SGA, state the authors.
"Increased uptake of folic acid prior to pregnancy and throughout the first trimester could have significant public health benefits given the poor outcomes associated with SGA babies. New strategies are therefore vital to improve the lives of both mothers and babies."
Khaled Ismail, Professor of Obstetrics and Gynaecology, University of Birmingham, co-author of the study.
Of 108 525 pregnancies with information about FA supplementation, 92 133 (84.9%) had taken FA during pregnancy. Time of commencement of supplementation was recorded in 39 416 pregnancies, of which FA was commenced before conception in 10 036, (25.5%) cases. Preconception commencement of FA supplementation was associated with reduced risk of SGA <10th centile (aOR 0.80, 95% CI 0.71–0.90, P < 0.01) and SGA <5th centile (aOR 0.78, 95% CI 0.66–0.91, P < 0.01). This result was reproduced when the data were pooled with other studies in the systematic review, showing a significant reduction in SGA (<5th centile) births with preconception commencement of FA (aOR 0.75, 95% CI 0.61–0.92, P < 0.006). In contrast, postconception folate had no significant effect on SGA rates.
Supplementation with FA significantly reduces the risk of SGA at birth but only if commenced preconceptually independent of other risk factors.
Hodgetts VA, Morris RK, Francis A, Gardosi J, Ismail KM. Effectiveness of folic acid supplementation in pregnancy on reducing the risk of small for gestational age neonates: A population study, systematic review and meta-analysis. BJOG 2014; http://dx.doi.org/10.1111/1471-0528.13202
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