Folic acid: abortifacient or pseudoabortifacient?

Trends of folate, vitamin B12 , and homocysteine levels in different trimesters of pregnancy and pregnancy outcomes

OBJECTIVE

To evaluate the effect of folate and vitamin B₁₂ levels on pregnancy progression and outcomes.

METHODS

The present study is a prospective follow up study of 100 pregnant women. Biochemical investigations (plasma homocysteine, folate, and vitamin B₁₂ levels) were performed on all pregnant women in first, second, and third trimesters. Nonparametric tests were used to compare the differences in median levels and odds ratio analysis for the assessment of the risk between the selected biomarkers and adverse pregnancy progression and outcomes.

RESULTS

The pregnant women at their first antenatal care visit were found to be predominantly folate replete (97%) and vitamin B₁₂ deficient (60%). Hyperhomocysteinemia in first and second trimesters was found to pose more than 3-fold increased risk for adverse pregnancy outcomes (P = .006 and .0002, respectively). Low birth weight (LBW) was found to be the most common adverse pregnancy outcome (52%), and was significantly associated with vitamin B₁₂ deficiency in the first and second trimesters (82%, P < .0001; 71.4%, P = .04, respectively).

CONCLUSION

The vitamin B₁₂ deficiency is more common among Indian pregnant women as compared to folate deficiency. Hyperhomocysteinemia is an independent risk factor for pregnancy complications. Vitamin B₁₂ deficiency in first and second trimesters is associated with LBW babies.

Periconceptional intake of vitamins and fetal death: a cohort study on multivitamins and folate

BACKGROUND

Women planning to conceive are often advised to take multivitamins. Whether this affects the survival of the fetus is not known.

METHODS

We used data from 35 914 women in the Danish National Birth Cohort who at recruitment had reported the number of weeks of supplement use during a 12-week periconceptional period. A telephone interview provided information about maternal characteristics and data on fetal death came from registers. The associations between periconceptional multivitamin or folate-only use and early (<20 weeks) and late (≥20 weeks) fetal death were estimated by hazard ratios (HR) with 95% confidence intervals (CI). Follow-up started at 8 completed weeks of gestation, and comparisons were made with no supplement use at any time during the periconceptional period.

RESULTS

Any multivitamin use was associated with a small increased crude risk of fetal death [HR 1.12 (1.01-1.25)], which was restricted to early losses [HR 1.18 (1.05-1.33)] compared with late losses [HR 0.82 (0.62-1.10)]. Adjustment for maternal factors increased this excess risk further. Whereas regular users of multivitamins (4-6 weeks of 6) before conception had more early losses [HR 1.29 (1.12-1.48)], a decreased risk of late losses was indicated when use started after conception [HR 0.65 (0.39-1.09)]. Folate-only use was not associated with fetal death.

CONCLUSIONS

Multivitamin use was associated with a modest increased risk of early fetal death. For late fetal death, regular supplement use after conception may decrease risk, but numbers were small. Further studies on preconceptional multivitamin use are needed to guide public health recommendations.

Spontaneous abortion and the prophylactic effect of folic acid supplementation in epileptic women undergoing antiepileptic therapy

BACKGROUND

Antiepileptic drugs (AEDs) like phenytoin (PHE), carbamazepine (CBZ), barbiturates and valproic acid (VPA) interfere with folic acid absorption and metabolism, which in turn can be the cause of adverse pregnancy outcome.

OBJECTIVE

To study the prophylactic effect of folic acid supplementation with regard to spontaneous abortion and preterm delivery (fetal demise after week 20 of gestational age) in pregnant women receiving AED therapy, as well as benefits of most common dosage and preconceptional commencement.

METHODS

Prospective examination of 104 patients, registered in EURAP from 1999-2004 at a single center and a retrospective analysis of data from our epilepsy databank completed with medical records and patients interviews of the Department of Neurology of Innsbruck University Hospital from 1971 to 1999.

RESULTS

388 pregnancies in 244 patients were analyzed. Pregnancies with folic acid supplementation showed significant reduction of spontaneous abortion. With regard to monotherapies, in the group of women taking VPA, supplementation of folic acid had significant benefit. Other examined monotherapies (CBZ, PHE, and PB) known to interfere with folic acid showed no significant results.

CONCLUSIONS

This study confirms the prophylactic effect of folic acid supplementation on spontaneous abortion. For AED therapy, folic acid supplementation should be part of the therapy of every pregnant epileptic woman, especially for those treated with VPA.

[Analysis of the frequencies of genotype combinations of 4 polymorphisms of genes acting on the folate cycle in the Spanish population]

BACKGROUND AND OBJECTIVE

Studies on different populations have shown a great variability of the frequencies of different polymorphisms in genes acting in the folate cycle. The present study was aimed to analyze the frequency in the Spanish population of each genotype combination of four polymorphisms, one of them -1561C-T of the glutamate carboxypeptidase II (GCPII) gene- being the first time that is studied in Spain. The study included a meta-analysis of the published data.

SUBJECTS AND METHOD

Using the Spanish Collaborative Study of Congenital Malformations (ECEMC) Network, blood samples of 190 mother-child couples with newborns without any congenital defect, were obtained from 15 Spanish autonomous regions. The study polymorphisms were the 677C-T and 1298A-C polymorphisms of the methylenetetrahydrofolate reductase (MTHFR), the 66A-G of the methionine synthase reductase (MTRR), and the 1561C-T polymorphism of the GCPII gene. To estimate the range for the population frequencies, 99% confidence intervals were calculated.

RESULTS

The frequencies observed in our country were significantly different from others, being similar to those obtained in countries of the Mediterranean European area. The 1561C-T polymorphism of the GCPII gene has a frequency in Spain of 5.11%, which is also similar to the values observed in France (5%) and in Italy (6%). On the other hand, the frequency of the genotypes CTCC, TTAC is quite few, while the genotype TTCC was not observed in any mother or infants. A meta-analysis was performed for a big sample (23,612 individuals) and the results showed that with a 99% of probability the values for the genotype combinations CTCC, TTAC, and TTCC were within 0.10-0.24; 0.20-0.36; and 0.003-0.05, respectively.

CONCLUSIONS

Our results are important to further analyze the relationship with some health problems and individual susceptibilities. Indeed, considering the published observations of the structure and function of the MTHFR enzyme, it is understandable that those genotype combinations that are quite little frequent, may be related to the embryo-fetal viability, and to the life style of each population.

Folic acid and methionine in the prevention of teratogen-induced congenital defects in mice

INTRODUCTION

Periconceptional supplementation with multivitamins containing folic acid reduces the risk of congenital malformations. We have previously investigated the effect on the murine development of a multiple retinoic acid competitive antagonist, Bristol-Myers-Squibb 189453, showing that treated fetuses were affected with heart defects, thymus aplasia or hypoplasia, and severe anomalies of the central nervous system. Hereby, we analyzed the effects of nutritive therapy involving folic acid and methionine on teratogen-induced congenital defects in mice.

MATERIALS AND METHODS

A total of 132 outbred CD1 litters were studied. Pregnant mice were divided into four experimental groups, and an oral supplementation of H(2)O or folic acid, or methionine, or folic acid+methionine was administered from 0.5 days postcoitum until the end of pregnancy. At 7.5 days postcoitum, mice from all these groups were administered Bristol-Myers-Squibb 189453 to induce the teratogenic effect. At the end of pregnancy, fetuses were dissected and tissues were analyzed by histology and flow cytometric assays.

RESULTS

Folic acid reduces congenital heart diseases from 81.3% to 64.8%, neural tube defects from 20.3% to 3.7%, and thymus abnormalities from 98.4% to 27.8%, restoring a normal number of differentiated thymus cells. Methionine is less effective in contrasting congenital heart diseases and neural tube defects, and induces thymus cell proliferation but not differentiation. Folic acid+methionine weakly reduce congenital heart diseases and neural tube defects, but consistently reduce the incidence of fetuses affected with thymus pathologies from 98.4% to 67.7%.

CONCLUSIONS

Our results suggest that folic acid and methionine periconceptional supplementations may influence the incidence of congenital defects and may probably induce negative selection of embryos presenting developmental anomalies.

Physiology of folate and vitamin B12 in health and disease

Folate is a water-soluble B-vitamin and enzymatic cofactor that is necessary for the synthesis of purine and thymidine nucleotides and for the synthesis of methionine from homocysteine. Impairment of folate-mediated one-carbon metabolic pathways can result from B-vitamin deficiencies and/or single nucleotide polymorphisms, and increases risk for pathologies, including cancer and cardiovascular disease, and developmental anomalies including neural tube defects. Although several well validated metabolic and genomic biomarkers for folate deficiency exist, our understanding of the biochemical and genetic mechanisms whereby impaired folate metabolism increases risk for developmental anomalies and disease is limited, as are the mechanisms whereby elevated folate intake protects against these pathologies. Therefore, current initiatives to increase folate intakes in human populations to ameliorate developmental anomalies and prevent disease, while effective, lack predictive value with respect to unintended adverse outcomes.

Bringing individuality to public health recommendations

The data generated from the human genome project offers unprecedented opportunities to elucidate the etiology of chronic diseases and developmental anomalies that arise from deleterious genome-diet interactions. Folate metabolism is an attractive system to explore such relationships. Folate is necessary for the synthesis of purine and thymidine deoxyribonucleotides and S-adenosylmethionine, a cofactor required for DNA methylation. Impaired folate metabolism results from primary folate deficiency, alcohol, gastrointestinal disorders that result in malabsorption, single nucleotide polymorphisms, increased folate catabolism and secondary nutrient deficiencies in vitamin B-6, vitamin B-12 and iron arising from a variety of pathologies. Any of these conditions singly or in combination influence DNA synthesis, DNA integrity, allelic-specific gene expression, chromatin structure and DNA mutation rates. Biochemical manifestations of impaired folate metabolism include increased uracil uptake into DNA, altered DNA methylation status and elevated homocysteine and S-adenosylhomocysteine in serum and tissues. These biochemical changes are associated with risk for cancer, cardiovascular disease, neural tube defects and some neuropathies and anemia, although direct causative mechanisms have not been established in all cases. Interactions between folate and the genome are reciprocal; polymorphisms in key genes influence folate nutritional requirements, indicating that dietary folate adequacy likely exerts selective pressure and thereby influences genetic variation. Other studies indicate that exposure to excess folate, perhaps at levels that occur at the upper end of the intake distribution curve, may have unintended consequences in promoting embryo viability. Therefore individualizing folic acid dietary recommendations necessitates a detailed understanding of all genetic and physiological variables that influence the interaction of folate with the genome and their relationship to the disease process.

Prevalence of aneuploidies in South Carolina in the 1990s

PURPOSE

Folate insufficiency due to nutritional deficiency or folate processing gene mutations has been proposed as a trisomy 21 risk factor. This study examined the possibility that increased folic acid intake among women of childbearing age may decrease the prevalence of trisomy 21 and other aneuploidies.

METHODS

The prevalence of aneuploidies from 1990 through 1999 was compared with folic acid use in women of childbearing age in South Carolina.

RESULTS

Folic acid use and the prevalence of all aneuploidies significantly increased during this period.

CONCLUSION

Increased folic acid utilization in South Carolina was not associated with decreased prevalence of trisomy 21 or other aneuploidies.