Folic Acid

The vast majority of Irish women have heard of folic acid, but most do not take it, a survey of Irish women by the Boyne Research Institute reported. A survey of Irish women of reproductive age (720kb PDF) showed that although nearly all women (95%) had heard of folic acid, and nearly three-quarters (72%) knew that it prevented spina bifida, only a small fraction (5.5%) were taking folic acid. Between October 2002 and March 2003, the Institute surveyed 500 women in Drogheda, sampled in order to be representative of the Irish population.

Folic acid, a B vitamin, prevents about 70% of new cases of neural tube defects, a group of defects of the brain and spinal cord, that include spina bifida. Rates of neural tube defects have gone down sharply in Ireland since 1950 when nearly one in every 100 babies was born with this sometime fatal condition. Now about one in every 1,000 Irish babies is born with a neural tube defect. A possible explanation lies in improvements in the Irish diet, such as more fresh fruit and vegetables, over the course of the last 60 years. Just the same, the Irish Department of Health recommends that all women between the ages of 15 and 44, who are capable of becoming pregnant, should take a 400 µg tablet of folic acid daily.

The Institute's first folic acid study was carried out among uncles and aunts in Irish families with a neural tube defect. This retrospective study showed that use of folic acid before and during pregnancy grew steadily during the years 1990-2000, reaching a level of nearly 60% of pregnancies supplemented beforehand and 90% supplemented during the pregnancy. However, pregnancies to smokers were less likely to be supplemented.

Published article (316Kb PDF)
PubMed abstract

BRI carried out an intervention study to increase folic acid use in these families, whose female relatives are at higher risk of themselves having a child with an NTD. The intervention was simple, consisting of a package of information and a sample of folic acid tablets. As measured by the differences reported by questionnaire before the intervention and after the intervention, the number of relatives taking folic acid doubled. Thus the intervention was successful. However the percentage of female relatives taking folic acid reached only 19% after the intervention.

Published article (544Kb PDF)
PubMed abstract

A second intervention study involving the Boyne Research Institute was carried out in families attending the Spina Bifida Clinic at Children's National Medical Center in Washington, DC. Female family members were interviewed before and after an intervention (as above, a mailed-out package of information), about their knowledge and use of folic acid. Again, the results were similar: relatives were very knowledgeable about folic acid and its benefits, but did not take folic acid as recommended. However, the intervention did increase both knowledge and use of folic acid among these relatives.

Published article (560Kb PDF)
PubMed abstract

Supplemental folic acid prevents miscarriage

Why did we do this study? Evidence that folic acid, taken as recommended, can prevent miscarriage, is seen in some, but not all, previous studies.

What did we do? We evaluated the protective effect of folate on miscarriage among first cousin once removed pregnancies, that is, pregnancies to first cousins.

What did we find? Our data indicate that the percentage of pregnancies that ended in miscarriage was 10.7% if folic acid pills were taken before pregnancy, compared to 13.8% of pregnancies miscarrying when the mother did not take folic acid before pregnancy.

The difference was bigger when women took folic acid pills during early pregnancy. Among these women, 9.6% of their pregnancies ended in miscarriage when they took folic acid pills compared to 15.7% of pregnancies to women who did not take folic acid during early pregnancy.

In the first case (folic acid taken before pregnancy) the difference was 0.65. That is, 35% of pregnancies that would have miscarried did not. In the second case, the difference was 0.37; that is, 63% of miscarriages were prevented.

So what? Our study supports others that found that folic acid prevents some proportion of miscarriages. Pre-pregnancy counselling should include the benefits of folic acid against miscarriage, as well as birth defects.

Published article (172Kb PDF)
PubMed abstract


graph of timing of supplemental folic acid

Timing of supplemental folic acid an important factor in preventing birth defects

Why did we do this study? It is well known that folic acid pills taken periconceptionally prevent birth defects. That is, the pills should be taken before pregnancy starts and for at least the first three months of pregnancy. While we showed that supplemental folic acid lowered the risk of miscarriage, the question remaining was: could we detect an effect of timing of folic acid intake.

What did we do? This analysis was undertaken among first cousins once removed, since many of them had been born since folic acid recommendations commenced.

What did we find? Among first cousin pregnancies that were supplemented, the most effective at preventing birth defects was folic acid intake both before and during pregnancy. Here 3.5% of pregnancies were born with a birth defect. Next most effective was folic acid intake during early pregnancy, with a birth defect rate of 4.6%. For women who did not take folic acid at all, the risk of birth defects was 8.2%. The linear trend was statistically significant (p-0.004).

So what? Clearly, the recommendation to commence taking folic acid before pregnancy begins and continue taking the pills during pregnancy is well-founded. None of these pregnancies had a neural tube defect, indicating the preventive effect of folic acid against other birth defects.



graph of amount of supplemental folic acid