Abstract
OBJECTIVES: To assess the effect of timing of folic acid (FA) supplementation during pregnancy on the risk of the neonate being small for gestational age (SGA).
DESIGN: A population database study and a systematic review with meta-analysis including the results of this population study.
SETTING AND DATA SOURCES: A UK regional database was used for the population study and an electronic literature search (from inception until August 2013) for the systematic review.
PARTICIPANTS AND INCLUDED STUDIES: Singleton live births with no known congenital anomalies; 111,736 in population study and 188,796 in systematic review.
OUTCOME MEASURES, DATA EXTRACTION AND ANALYSIS: The main outcome was SGA based on customised birthweight centile. Associations are presented as odds ratios (OR) and adjusted odds ratios (aOR), adjusted for maternal and pregnancy-related characteristics.
RESULTS: 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.
CONCLUSION: Supplementation with FA significantly reduces the risk of SGA at birth but only if commenced preconceptually independent of other risk factors.
SYSTEMATIC REVIEW REGISTRATION: This systematic review was prospectively registered with PROSPERO number CRD42013004895.
Original language | English |
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Pages (from-to) | 478-90 |
Number of pages | 13 |
Journal | BJOG: An International Journal of Obstetrics & Gynaecology |
Volume | 122 |
Issue number | 4 |
Early online date | 26 Nov 2014 |
DOIs | |
Publication status | Published - Mar 2015 |
Keywords
- Adult
- Birth Weight
- Dietary Supplements
- Female
- Fetal Development
- Folic Acid
- Great Britain
- Health Knowledge, Attitudes, Practice
- Humans
- Infant, Newborn
- Infant, Small for Gestational Age
- Pregnancy
- Pregnancy Outcome
- Prenatal Nutritional Physiological Phenomena
- Risk Factors