The results are based on a study of folate supplementation by 38,033 participants, researchers from the University of Texas Medical Branch at Galveston told attendees at the 28th Annual Society for Maternal-Fetal Medicine (SMFM) meeting.
According to the researchers, this study represents the first and largest U.S. study to look at the effects of folate supplementation prior to conception on early pre-term delivery.
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.
Lead researcher Radek Bukowski told attendees that the benefits were of particular note against very early premature births, those babies who are at the greatest risk of complications such as cerebral palsy, mental retardation, chronic lung disease, and blindness.
The study is an observational analysis based on data from an earlier trial sponsored by the National Institutes of Health (NIH).
"Thanks to the depth and breadth of the NIH study, which included an early pregnancy ultrasound of each participant, we had highly accurate evidence of the gestational ages of the preterm deliveries," said Bukowski.
"This evidence enabled us to determine that folate supplementation for at least one year is linked to a 70 per cent decrease in very early preterm deliveries (20 to 28 weeks in gestational age) and up to a 50 per cent reduction in early preterm deliveries of 28 to 32 weeks."
Bukowski and co-workers limited their study to singleton pregnancies and excluded pregnancies with complications including pre-eclampsia, chronic hypertension, and congenital or chromosomal abnormalities.
The research was welcomed by leading non-profit organization for pregnancy and baby health, March of Dimes. Commenting on the research, Alan Fleischman, senior vice president and medical director said: "Dr. Bukowski's research makes us optimistic that taking folic acid for at least one year before pregnancy also may greatly reduce the risk of premature birth.
"We hope this new research also will spur more health care professionals to urge their female patients to make folic acid part of their daily routine as a simple step toward having a healthy baby in the future."
Katharine Wenstrom, president of the Society for Maternal-Fetal Medicine (SMFM), said: "In addition to its benefits in preventing pregnancy complications, previous studies have suggested that folic acid may also have beneficial effects in preventing stroke and cardiovascular disease in adults."
Further benefits of folic acid and folate intakes were reported recently by Norwegian scientists. Writing in the British Medical Journal (doi: 10.1136/bmj.39079.618287.0B), researchers reported that folic acid supplements during early pregnancy could also reduce the risk of cleft lip in infants by 33 per cent.
Source: 28th Annual Society for Maternal-Fetal Medicine (SMFM) meeting
"Preconceptional Folate Prevents Preterm Delivery"
Authors: R. Bukowski et al.
