Prevention of neural-tube defects with folic acid in China. China-U.S. Collaborative Project for Neural Tube Defect Prevention

Methylenetetrahydrofolate reductase C677T polymorphism and the risk of unexplained recurrent pregnancy loss: a meta-analysis

OBJECTIVE

To investigate the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and the risk of unexplained recurrent pregnancy loss (URPL).

DESIGN

Meta-analysis of published case-control studies of the MTHFR C677T variant and URPL risk.

SETTING

A research institution in China.

PATIENT(S)

Women with URPL.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Odds ratios (ORs) and 95% confidence intervals (CIs) for TT versus CC genotype, CT versus CC genotype, TT versus CT and CC genotype combined, and for T versus C allele.

RESULT(S)

Twenty-six studies with 2120 URPL cases and 2949 controls were included. Overall random-effects ORs of 1.49 (95% CI, 1.12-2.00) for TT versus CC genotype, 1.40 (95% CI, 1.11-1.77) for TT versus CT and CC genotype combined, and 1.21 (95%CI, 1.04-1.40) for T versus C allele were found. Stratified analysis showed that significant strong associations between MTHFR C677T polymorphism and URPL were present only in the five Chinese studies (OR = 2.96 for TT versus CC genotype; OR = 2.30 for TT versus CT+CC genotype; OR = 1.73 for T versus C allele), but not in any other studies, including the studies conducted in the European countries.

CONCLUSION(S)

The MTHFR C677T mutation is not a genetic risk factor for URPL except in a Chinese population.

Exogenous glycine partially attenuates homocysteine-induced apoptosis and membrane peroxidation in chick embryos

The effects of exogenous glycine on homocysteine (HoCys)-induced reductions in chick (Gallus gallus) embryo viability, HoCys-induced increases in brain and hepatic membrane lipid peroxidation, HoCys-induced apoptosis (caspase-3 activities) in brain and hepatic tissues, and HoCys-induced reductions in brain and hepatic S-adenosylemethionine (SAM)/S-adenosylhomocysteine (SAH) levels were studied. Exogenous HoCys caused reductions in percent living embryos and reductions in embryo masses. Exogenous glycine attenuated these HoCys-induced reductions in embryo viability. Brain and liver tissues of HoCys-treated embryos exhibited increased caspase-3 activities, increased lipid hydroperoxide (LPO) levels, and reduced levels of long-chain polyunsaturated membrane fatty acids. While exogenous glycine attenuated HoCys-induced changes in brain caspase-3 activities, brain LPO levels, and brain membrane PUFA levels, exogenous glycine was less effective in attenuating HoCys-induced changes in hepatic caspase-3 activities and hepatic membrane PUFA levels. HoCys-induced reductions in SAM/SAH ratios were observed in brains and livers. Exogenous glycine attenuated HoCys-induced reductions in brain SAM/SAH. However, glycine was unable to attenuate HoCys-induced reductions in hepatic SAM/SAH levels.

Neural tube defects and folate: case far from closed

Neural tube closure takes place during early embryogenesis and requires interactions between genetic and environmental factors. Failure of neural tube closure is a common congenital malformation that results in morbidity and mortality. A major clinical achievement has been the use of periconceptional folic acid supplements, which prevents approximately 50-75% of cases of neural tube defects. However, the mechanism underlying the beneficial effects of folic acid is far from clear. Biochemical, genetic and epidemiological observations have led to the development of the methylation hypothesis, which suggests that folic acid prevents neural tube defects by stimulating cellular methylation reactions. Exploring the methylation hypothesis could direct us towards additional strategies to prevent neural tube defects.

Weekly Administration of Folic Acid and Epidemiology of Neural Tube Defects

OBJECTIVE

In 1999, a folic acid campaign for prevention of neural tube defects was started in Nuevo León, México, with the recommendation of taking a 5000 -mcg tablet of folic acid per week. The purpose of this study was to compare the epidemiology of neural tube defects after four years of the campaign.

METHODS

Cases of anencephaly, spina bifida, and encephalocele (ICD Q00, Q01, Q05, 10th Ed.) from public and private hospitals were registered by immediate notification, death certificates, and fetal death registries. Comparisons of neural tube defects rates, phenotype distribution of cases, and sex ratios, registered before and after the folic acid campaign, were done using the Student's t Test and Chi square test.

RESULTS

There was a 50% reduction in the incidence of anencephaly and spina bifida cases from 93 in 1999 (1.04x1000) to 46 in the year 2003 (0.56x1000) (p<0.001). Spina bifida cases declined up to 70% in 2002 and anencephaly cases up to 50% in 2003. In 1999, overall, the ratio (females: males) was 0.66 with female excess; the sex ratio was similar for anencephaly and spina bifida cases. In the year 2000, female cases showed a significant reduction for both spina bifida and anencephaly (75% and 56% respectively); the sex ratio was 0.57 with a greater male excess for both phenotypes.

CONCLUSIONS

Weekly administration of 5000 mcg of folic acid reduces the incidence of neural tube defects 50%, primarily spina bifida, with a higher reduction of female cases.

Folate intakes and folate biomarker profiles of pregnant Japanese women in the first trimester

OBJECTIVE

To assess the status of dietary folate intake, serum and red blood cell (RBC) folate, and related nutritional biomarkers in healthy Japanese women in early pregnancy.

DESIGN

A cross-sectional, observational study.

SUBJECTS

Pregnant women in the first trimester, at 7-15 weeks gestation (n=70), who were not consuming any folate supplements or folate fortified foods.

METHODS

Three-day dietary records were obtained from each subject to assess dietary folate intake. Blood samples were collected for measurement of biomarkers. Biomarkers and nutrient intake were analyzed in two groups defined by their serum folate concentrations: the low folate group (serum folate < 9 ng/ml) and the high folate group (serum folate > or = 9 ng/ml).

RESULT

Mean serum and RBC folate concentrations in all subjects were 10.3 and 519 ng/ml, respectively. These levels were remarkably higher than the reported values from many other countries despite our subjects receiving no folic acids supplements. However, mean folate intake by our subjects from natural foods was 289 microg/day, which is thought to be low according to the Japanese dietary recommendation specified for pregnant women. The intake of spinach and fruits was significantly greater in the high folate group than in the low folate group.

CONCLUSION

Folate intake was thought to be adequate to maintain a desirable level of serum folate concentration in Japanese pregnant women in the first trimester, although the intake of folate from natural food was not high enough to meet the recommended daily intake.

Increasing trend of spina bifida and decreasing birth weight in relation to declining body-mass index of young women in Japan

We analyzed the existing data from various surveys on the prevalence of spina bifida, birth weight, and body-mass index (BMI), dietary intake, and smoking habits of Japanese young women. We found that the increasing trend of the prevalence of spina bifida paralleled with the decrease in birth weight, and the decrease in BMI and dietary energy intake and the increase in smoking rate among women of childbearing age. The decreased energy intake is likely due to their distorted self-body image. Based on these findings, we hypothesize that lowering BMI in young women led to increasing prevalence of spina bifida and smaller babies in Japan. This low dietary intake possibly leads to poor folate nutritional status, a risk factor for the development of spina bifida, and increased smoking potentially accelerates these undesirable outcomes. Our hypothesis can be tested using two simultaneous approaches. The first step is an extensive educational campaign for young women to stop smoking, have a realistic body image and eat a sufficient balanced diet. Government officials and health-care workers are encouraged to establish an agenda to educate young women with emphasis on the importance of adequate nutrition during the critical period of reproduction. Together with this campaign, the distribution of folic acid tablets for the prevention of spina bifida can be tried in women of childbearing age through local health centers, which have been well established in Japan.

Acquired and inherited disorders of cobalamin and folate in children

Cobalamin deficiency in the newborn usually results from cobalamin deficiency in the mother. Megaloblastic anaemia, pancytopenia and failure to thrive can be present, accompanied by neurological deficits if the diagnosis is delayed. Most cases of spina bifida and other neural tube defects result from maternal folate and/or cobalamin insufficiency in the periconceptual period. Polymorphisms in a number of genes involved in folate and cobalamin metabolism exacerbate the risk. Inborn errors of cobalamin metabolism affect its absorption, (intrinsic factor deficiency, Imerslund-Gräsbeck syndrome) and transport (transcobalamin deficiency) as well as its intracellular metabolism affecting adenosylcobalamin synthesis (cblA and cblB), methionine synthase function (cblE and cblG) or both (cblC, cblD and cblF). Inborn errors of folate metabolism include congenital folate malabsorption, severe methylenetetrahydrofolate reductase deficiency and formiminotransferase deficiency. The identification of disease-causing mutations in specific genes has improved our ability to diagnose many of these conditions, both before and after birth.

Extremely high prevalence of neural tube defects in a 4-county area in Shanxi Province, China

BACKGROUND

In the past, northern China's Shanxi Province has reported the highest incidence of neural tube defects (NTDs) in the world. However, little is known about the epidemiology of NTDs in this area in recent years.

METHODS

Data were collected from a population-based birth defects surveillance system in 4 counties that captures information on all live births, stillbirths of at least 20 weeks' gestation, and pregnancy terminations at any gestational age resulting from prenatal diagnosis of a birth defect. We also surveyed mothers of NTD case patients to determine their use of folic acid before and during early pregnancy.

RESULTS

During 2003, 160 NTD cases were identified among 11,534 births (NTD birth prevalence = 138.7/10,000 births). The rates of anencephaly, spina bifida and encephalocele were 65.9, 58.1, and 14.7 per 10,000, respectively, and a female predominance was observed among anencephaly cases (male-to-female relative risk [RR], 0.49; 95% confidence interval [CI], 0.30-0.79), but not among spina bifida (RR, 0.90; 95% CI, 0.55-1.45) and encephalocele (RR, 1.03; 95% CI, 0.40-2.69) cases. The percentages of pregnancy termination following prenatal diagnosis of anencephaly, spina bifida, and encephalocele were 50%, 41.8%, and 35.3%, respectively. NTD birth prevalence tended to be higher among mothers aged <20 or > or =30 years (P = .06) and was markedly associated with lower levels of maternal education (P < .001). Among 143 NTD mothers, only 6 (4.2%) used folic acid supplements during the periconceptional period.

CONCLUSIONS

The NTD birth prevalence rate in the study area is among the highest worldwide. Folic acid deficiency may be one important risk factor.

Failure of homocysteine to induce neural tube defects in a mouse model

BACKGROUND

Folate deficiencies have been associated with many adverse congenital abnormalities. It is not clear, however, whether these defects are due to a folate deficiency or to an increase in homocysteine. Homocysteine has been shown to be teratogenic in the chicken-embryo model and it has been suggested that homocysteine-induced defects are mediated by inhibiting the N-methyl-D-aspartate (NMDA) receptor on neural crest cells. The majority of the teratology studies have been carried out using the chicken embryo model. In an effort to develop a murine model of homocysteine-induced neural tube defects, several inbred mouse strains were treated with homocysteine or the NMDA inhibitor MK801 and the fetuses examined for any induced-NTD.

METHODS

Several in-bred mouse strains were administered homocysteine once on gestational day (GD) E8.5 or once daily on GD 6.5-10.5. Additionally, because homocysteine was been reported to mediate its effects through the NMDA receptor, the effect of MK801, an antagonist of this receptor, was also investigated.

RESULTS

Regardless of the mouse treatment time, homocysteine failed to induce neural tube defects in our in-bred mouse strains. Homocysteine also failed to increase the number of neural tube defects in the splotch strain, regardless of the genotype.

CONCLUSIONS

Irrespective of the mouse strain or treatment, homocysteine failed to induce neural tube defects in our mouse models, which is in contrast to what has been reported in the chicken embryo models.

The impact of prenatal diagnosis on neural tube defect (NTD) pregnancy versus birth incidence in British Columbia

The birth incidence of neural tube defect (NTD) cases in British Columbia (B.C.), and elsewhere in North America, is reported to be declining. This decline is being attributed to folic acid (FA) supplementation and food fortification, but 2nd trimester prenatal screening of pregnancies for NTDs and other congenital anomalies has increased during this timeframe, as well. This descriptive, population-based study evaluates the impact of prenatal screening of NTD-affected pregnancies on (1) pregnancy outcome and (2) reporting of NTD births to the provincial Health Status Registry (B.C.H.S.R.); and it assesses (3) the use of periconceptional FA supplementation. NTD cases were ascertained from medical records of health centres providing care to families with NTD-affected pregnancies and newborns; and from NTD cases reported to the B.C.H.S.R. In 1997-1999, the B.C.H.S.R. published a NTD incidence of 0.77/1000. In this study, 151 NTD-affected pregnancies were identified, with an incidence of 1.16/1000. Partial Reporting of induced abortions in a NTD incidence 45.5% low than the actual incidence. Medical records were available for review on 144/151 pregnancies. Prenatal screening identified 86.1% (124/144) of NTD-affected pregnancies, with 72.6% (90/124) resulting in pregnancy termination, and 27.4% (34/124) continuing to term. Use of FA supplementation in the periconceptional period was recorded in 36.4% of pregnancies (39/107). Thus in B.C. the decline in the NTD incidence is due predominantly to pregnancy terminations following prenatal diagnosis, which reduces the NTD incidence by 60%, from 1.16/1000 to 0.47/1000. Continued efforts for primary and the option of secondary prevention of NTDs are recommended in order to improve newborn health in B.C. and elsewhere. These interventions need to be monitored, however, for optimal health care planning.

The expression of the NR1-subunit of the NMDA receptor during mouse and early chicken development

It has been suggested that homocysteine-induced defects are mediated by the inhibition of the N-methyl-d-aspartate (NMDA) receptor on neural crest cells. However, the majority of this work has been performed using the chicken embryo model. In an effort to better understand the molecular events involved a murine model of homocysteine-induced defects was sought. However, it has been previously shown that homocysteine failed to induce congenital defects in several strains of mouse. Therefore, in an effort to better understand the difference in the susceptibility between these two species we investigated the ontogeny of the NMDA receptor in the mouse and chicken. To determine the expression of the NMDA receptor we performed Western blot analysis using an antibody to the NR1-subunit of the NMDA receptor in both the chicken and mouse embryos. Further, we used RT-PCR to determine the temporal expression of this subunit in the murine embryos from gestational day 8.5 to 18.5 to confirm our Western blot analysis. Results from these studies demonstrated that the expression of the NMDA receptor was expressed during the early stages of development in the chick embryo but neither the transcript nor the protein was detected in mouse embryos until later in development. These results demonstrate that during the stages of neurulation and/or early heart development the expression of the NR1-subunit of the NMDA receptor was not detected. The expression of this gene increased and was detectable by gestational days 14.5-15.5 and continued to increase in its expression until term. Therefore, these experiments suggest that homocysteine-induced defects may be mediated via the NMDA receptor.

Low folic acid status and its association with anaemia in urban adolescent girls and women of childbearing age in Sri Lanka

Folic acid deficiency is implicated in the aetiology of nutritional anaemia and adverse pregnancy outcomes for the fetus. Data on folic acid status among adolescent girls and non-pregnant, non-lactating young women are limited. We assessed folic acid status in a random sample of 552 subjects (277 adolescent girls aged 15-18.9 years and 275 women aged 19-30 years) living in Colombo, Sri Lanka. The association of low folic acid status with anaemia was evaluated. Socio-economic, food intake and anthropometric data were obtained. Hb, serum folic acid, vitamin B12 and ferritin and plasma homocysteine concentrations were measured. Forty-three per cent of subjects studied had low serum folic acid concentrations (<3 ng/ml) and 47 % had low Fe stores (serum ferritin <20 microg/l). Overall prevalence of anaemia was 12.9 %, and 43.9 % of anaemic subjects had both low folic acid status and depleted Fe stores (serum ferritin <12 microg/l). Both low folate status and depleted Fe stores were significantly associated with anaemia (odds ratio = 2.32; 95 % CI 1.34, 4.01 and odds ratio = 5.98; 95 % CI 3.36, 10.63, respectively). Serum folic acid concentration was associated (r = 0.108, P = 0.015) with folate intake as indicated by a computed folate index. Folate index was associated inversely with household size and positively with economic status and education level. In this study population low folic acid status, besides depleted Fe stores, was associated with anaemia. The high prevalence of low folic acid status observed highlights the need for nutrition education to improve intakes of folate, Fe and other micronutrients among adolescent girls and young women.

Folate and human reproduction

The influence of folate nutritional status on various pregnancy outcomes has long been recognized. Studies conducted in the 1950s and 1960s led to the recognition of prenatal folic acid supplementation as a means to prevent pregnancy-induced megaloblastic anemia. In the 1990s, the utility of periconceptional folic acid supplementation and folic acid food fortification emerged when they were proven to prevent the occurrence of neural tube defects. These distinctively different uses of folic acid may well be ranked among the most significant public health measures for the prevention of pregnancy-related disorders. Folate is now viewed not only as a nutrient needed to prevent megaloblastic anemia in pregnancy but also as a vitamin essential for reproductive health. This review focuses on the relation between various outcomes of human reproduction (ie, pregnancy, lactation, and male reproduction) and folate nutrition and metabolism, homocysteine metabolism, and polymorphisms of genes that encode folate-related enzymes or proteins, and we identify issues for future research.

Folic acid: a public-health challenge

Despite worldwide public-health campaigns recommending periconceptional daily supplementation of synthetic folic acid to reduce the risk of neural tube defects, many women are not following these recommendations. At the same time, in most European countries no decline in defects has been recorded in recent years. Vulnerable groups are those with a low standard of education, young people, and women with unplanned pregnancies. Furthermore, in most countries without mandatory fortification, the general population is not consuming the recommended 0.4 mg of food folate per day. Voluntary fortification improves the situation, but does not reach all parts of the population. In the USA, Canada, and Chile, mandatory fortification of flour substantially improved folate and homocysteine status, and neural tube defects rates fell by between 31% and 78%. Nevertheless, many countries do not choose mandatory folic acid fortification, in part because expected additional health benefits are not yet scientifically proven in clinical trials, in part because of feared health risks, and because of the issue of freedom of choice. Thus, additional creative public-health approaches need to be developed to prevent neural tube defects and improve the folate status of the general population.

Applicability of alkyl-bonded ultra-pure silica stationary phases for gradient reversed-phase HPLC of folates with conventional and volatile buffers under highly aqueous conditions

Applicability of several alkyl-bonded silica stationary phases was tested for gradient RP-HPLC of folates under highly aqueous conditions. High retention of folates was achieved on alternative phases with enhanced polarity and classical phases with higher carbon content. Phases exhibiting polar secondary interactions were found to provide better selectivity for late-eluting folates, whereas selectivity for early-eluting folates was mostly dependent on hydrophobic interactions. Best selectivity in phosphate buffered mobile phase was achieved on polar-endcapped silica phases (Aquasil C18 and HyPurity Aquastar) followed by alternative Atlantis dC18. Classical phases exhibited poorer separation of 10-formyl-folic acid and 5-formyl-tetrahydrofolate, but it could be considerably improved by increasing the buffer pH. Strong secondary interactions of ion-exchange character on polar-embedded phases resulted in marked peak deterioration, loss of recovery and dramatic changes in retention behaviour for early- and late-eluting folates when changing the mobile phase composition and pH. Therefore, polar-embedded phases such as HyPurity Advance were found to be unsuitable for separating folates. Stationary phases exhibited peak deterioration when using volatile buffer of low ionic strength. Better results were obtained with classical phases, whereas alternative phases showed not only peak deterioration but also a decrease in recovery and poorer selectivity due to increased secondary interactions in volatile buffer.

Awareness and use of folic acid, and blood folate concentrations among pregnant women in northern China--an area with a high prevalence of neural tube defects

BACKGROUND

The prevalence of neural tube defects (NTDs) in northern China remains high after 10 years since periconceptional supplementation with folic acid has been known to be effective in reducing the risk of NTDs.

OBJECTIVE

The objectives of this study were to characterize folic acid awareness and use and to examine the association between folic acid supplementation with blood folate concentrations among early pregnant women in an area with a high prevalence of NTDs in northern China.

SUBJECT AND METHOD

From December 2002 to February 2004, 693 early pregnant women were recruited and interviewed about folic acid awareness, knowledge and use. Four millilitres of venous blood was drawn and blood folate concentrations were measured.

RESULTS

About 36% of women reported having ever heard of folic acid. Of these, 82.7% knew that folic acid can prevent NTDs, and 64.5% knew the best time to take it. Overall, 15% of women reported having ever taken folic acid. However, only 34.3% had begun to take it before the last menstrual period. Women with less education (21.1%), farmers (19.6%), rural dwellers (23.5%), and women who had a previous child (23.0%) were less likely to be aware of folic acid, and were less likely to take folic acid. Among women who had ever heard of folic acid, 37.5% took it during current pregnancy, compared with only 2.0% among those who had not. Women who were aware of folic acid were 25 times more likely to take it than women who were not. Overall, 44% of women had plasma folate deficiency, and 35% had red cell folate deficiency. Those who reported having ever taken folic acid had a lower rate of plasma folate deficiency (13.7%), compared with those who reported not taking folic acid (49.4%). The former group's mean plasma concentrations were twice as high as those of the latter group.

CONCLUSION

The levels of folic acid awareness, knowledge and use among Chinese women living in a high NTD prevalence area during early pregnancy were very low and folate deficiency was quite prevalent. Campaigns aimed at increasing the awareness, knowledge, and periconceptional use of folic acid should target to less educated, parous women and women living in rural areas.

Erythrocyte folate, plasma folate and plasma homocysteine during normal pregnancy and postpartum: a longitudinal study comprising 404 Danish women

OBJECTIVE

To assess folate and homocysteine status during normal pregnancy and postpartum in a longitudinal setting.

METHODS

This study, performed in 1995-1996, comprised 404 healthy pregnant Danish Caucasian women residential in Copenhagen County. Women taking folic acid tablets or vitamin B12 injections were not included. Dietary multivitamin supplements containing folic acid 100 microg or vitamin B12 1 microg, taken by 34%, were discontinued at inclusion. Participants had normal renal function. Folate status [erythrocyte (Ery-) folate, plasma (P-) folate, P-homocysteine] was measured at 18, 32 and 39 wk of gestation and 8 wk postpartum when the women were lactating.

RESULTS

Through 18, 32 and 39 wk of gestation and postpartum, P-folate demonstrated a significant fall: median values were 14.4, 10.2, 9.3 and 8.9 nmol/L, respectively (P < 0.0001). The prevalence of low P-folate <6 nmol/L increased during pregnancy from 0.7% to 19.0% postpartum (P < 0.0001). Ery-folate displayed a similar, significant fall: median value was 0.84, 0.75, 0.65 and 0.55 micromol/L, respectively (P < 0.0001). The prevalence of low Ery-folate <0.40 micromol/L increased during pregnancy from 0.5% to 17.2% postpartum (P < 0.0001). P-homocysteine demonstrated a significant increase: median value was 6.4, 7.0, 7.7 and 10.8 micromol/L, respectively (P < 0.0001). The prevalence of P-homocysteine >13 micromol/L increased during pregnancy from 0.7% to 20.8% postpartum (P < 0.0001). The prevalence of low folate status (defined as P-folate <6 nmol/L and P-homocysteine >13 micromol/L) was 0%, 0%, 1.2%, and 8.4% at 18, 32 and 39 wk of gestation and 8 wk postpartum, respectively.

CONCLUSION

Low folate status occurs among Danish pregnant women, especially in late pregnancy and postpartum during lactation. Despite new guidelines for folic acid supplement since 1997, only 13% of pregnant women followed the guidelines in 2003. The official recommendations for periconceptional folic acid supplement should be reconsidered and reinforced.

Research goals for folate and related B vitamin in Europe

In the past decade, the understanding of folate bioavailability, metabolism and related health issues has increased, but several problems remain, including the difficulty of delivering the available knowledge to the populations at risk. Owing to the low compliance of taking folic acid supplements, for example, among women of child-bearing age who could lower the risk of having a baby with a neural tube defect, food-based strategies aimed at increasing the intake of folate and other B-group vitamins should be a priority for future research. These should include the development of a combined strategy of supplemental folate (possibly with vitamin B(12)), biofortification using engineered plant-derived foods and micro-organisms and food fortification for increasing folate intakes in the general population. Currently, the most effective population-based strategy to reduce NTDs remains folic acid fortification. However, the possible adverse effect of high intakes of folic acid on neurologic functioning among elderly persons with vitamin B(12) deficiency needs urgent investigation. The results of ongoing randomized controlled studies aimed at reducing the prevalence of hyperhomocysteinemia and related morbidity must be available before food-based total population approaches for treatment of hyperhomocysteinemia can be recommended. Further research is required on quantitative assessment of folate intake and bioavailability, along with a more thorough understanding of physiological, biochemical and genetic processes involved in folate absorption and metabolism.

A population-based case-control study of risk factors for neural tube defects in four high-prevalence areas of Shanxi province, China

Shanxi province in Northern China has one of the highest reported prevalence rates of neural tube defects (NTD) in the world. To explore the risk factors for NTDs in Shanxi province, we carried out a population-based case-control study in four selected counties with prevalence rates >10 per 1000 births during 2003. Using a multi-logistic regression model analysis (alpha = 0.10), 158 NTD cases were compared with 226 control mothers. Maternal factors significantly associated with increased risk for an NTD were a primary school education or lower (adjusted odds ratio [OR] 2.32, 95% confidence interval [CI] 1.09, 4.97); a history of a previous birth defect-affected pregnancy (adjusted OR 5.27, 95% CI 0.98, 28.37); history of a fever or 'cold' (adjusted OR 3.36, 95% CI 1.68, 6.72); use of analgesic and antipyretic drugs (adjusted OR 4.89, 95% CI 0.92, 25.97); daily passive exposure to cigarette smoke (adjusted OR 1.60, 95% CI 0.94, 2.73); poor ventilation during heating (adjusted OR 3.91, 95% CI 0.75, 20.81); and consumption of >or= six meals per week containing pickled vegetables (adjusted OR 3.86, 95% CI 1.11, 13.47) during pregnancy. Factors which appeared to be protective were meat consumption one to three times per week (adjusted OR 0.62, 95% CI 0.37, 1.06), or >or= four times per week (adjusted OR 0.28, 95% CI 0.11, 0.77); and legume consumption >or= six times per week (adjusted OR 0.39, 95% CI 0.17, 0.89). Differences in risk were found between the two most common phenotypes, anencephaly and spina bifida. Most of the environmental factors had stronger positive and negative associations with risk for anencephaly rather than spina bifida, whereas history of a previous birth defect-associated pregnancy, as well as legume consumption, were more strongly associated with the risk for spina bifida than for anencephaly. The findings suggest that aetiological heterogeneity may exist between anencephaly and spina bifida.

Trends of selected malformations in relation to folic acid recommendations and fortification: An international assessment

BACKGROUND

Two crucial issues relative to the benefits and impact of folic acid in the prevention of birth defects are whether supplementation recommendations alone, without fortification, are effective in reducing the population-wide rates of neural tube defects (NTDs), and whether such policies can reduce the occurrence of other birth defects. Using data from 15 registries, we assessed rates and trends of 14 major defects, including NTDs, in areas with official recommendations or fortification to assess the effectiveness of recommendations and fortification on a wide range of major birth defects.

METHODS

We evaluated surveillance data through 2003 on major birth defects from population-based registries from Europe, North America, and Australia. All included ascertainment of pregnancy terminations (where legal). Trends before and after policies or fortification were assessed via Poisson regression and were compared via rate ratios.

RESULTS

Significant changes in trends were seen for NTDs in areas with fortification but not in areas with supplementation recommendations alone. For other major birth defects, there was an overall lack of major trend changes after recommendations or fortification. However, some significant declines were observed for select birth defects in individual areas.

CONCLUSIONS

Recommendations alone remain an ineffective approach in translating the known protective effect of folic acid in population-wide decline in NTD rates. Fortification appears to be effective in reducing NTDs. The effect on other birth defects remains unclear.

A known functional polymorphism (Ile120Val) of the human PCMT1 gene and risk of spina bifida

Folate binding protein 1 (Folr1) knockout mice with low maternal folate concentrations have been shown to be excellent animal models for human folate-responsive neural tube defects (NTDs). Previous studies using the Folr1 knockout mice revealed that maternal folate supplementation up-regulates the expression of the PCMT1 gene in Folr1 nullizygous neural tube tissue during neural tube closure. PCMT1 encodes the protein repair enzyme l-isoaspartate (d-aspartate) O-methyltransferase (PIMT) that converts abnormal d-aspartyl and l-isoaspartyl residues to the normal l-aspartyl form. PIMT is known to protect certain neural cells from Bax-induced apoptosis. Pcmt1-deficient mice present with abnormal AdoMet/AdoHcy homeostasis. We hypothesized that a known functional polymorphism (Ile120Val) in the human PCMT1 gene is associated with an increased risk of folate-responsive human NTDs. A case-control study was conducted to investigate a possible association between this polymorphism and risk of spina bifida. Compared to the Ile/Ile and Ile/Val genotypes, the homozygous Val/Val genotype showed decreased risk for spina bifida (adjusted odds ratio=0.6, 95% confidence interval: 0.4-0.9). Our results showed that the Ile120Val polymorphism of PCMT1 gene is a genetic modifier for the risk of spina bifida. Val/Val genotype was associated with a reduction in risk for spina bifida.

Folate concentrations and folic acid supplementation among women in their first trimester of pregnancy in a rural area with a high prevalence of neural tube defects in Shanxi, China

BACKGROUND

Although an information campaign concerning periconceptional folic acid supplementation was launched in 1998 in Shanxi Province, China, the prevalence of neural tube defects in rural areas was reported as high as 140 per 10,000 births in 2002. The blood folate concentrations and the practice of folic acid supplementation among pregnant women in rural areas of the province are described.

METHODS

A total of 483 pregnant women (mean gestation, 8.1 weeks) in a rural area of Shanxi were interviewed. Nonfasting blood samples and information on folic acid supplementation were collected. Folate concentrations in plasma and erythrocytes were determined by a microbiological assay.

RESULTS

The mean concentrations of plasma and erythrocyte folate for pregnant women was 10.4 nmol/liter and 375.8 nmol/liter, respectively. Deficiencies of plasma and erythrocyte folate were observed in 20.9% and 47.6% of women, respectively. Seasonal variations were noted in the prevalence of folate deficiency, with significantly lower plasma folate concentrations in spring and summer and lower erythrocyte folate concentrations in seasons other than summer. Among pregnant women, <10% reported having taken or currently taking folic acid, and virtually no women (0.6%) took folic acid as recommended.

CONCLUSIONS

Women in rural areas had low plasma and erythrocyte folate levels, and folate deficiency was highly prevalent in the area. Few women followed the recommendations regarding folic acid supplementation, and the information campaign in Shanxi was unsuccessful. These findings suggest the urgent need for combined strategies in rural areas to fortify grain with folic acid and promote folic acid supplements for childbearing-age women.

Maternal and offspring MTHFR gene C677T polymorphism as predictors of congenital atrial septal defect and patent ductus arteriosus

To observe the association of MTHFR gene C677T locus polymorphism with occurrence of congenital heart defects (CHDs), 21 patients with atrial septal defect (ASD), 35 patients with patent ductus arteriosus (PDA), one patient with both conditions combined, and their biological parents were collected as the case group. Another 104 normal individuals and their biological parents without a family history of birth defects were selected as the control group. MTHFR C677T genotypes of each sample were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results showed for the occurrence of ASD, the odds ratio (OR) of TT genotype was 4.08 [95% confidence interval (95% CI) = 1.28-13.24] compared with CT genotype. For the occurrence of PDA, the ORs of TT were 3.44 (95% CI = 0.89-16.13) and 2.38 (95% CI = 0.92-6.14) compared with CC and CT genotypes, respectively. Author as meant? Compared with CC + CT genotype combination, the ORs of TT were 3.95 (95% CI = 1.38-11.44) and 2.60 (95% CI = 1.02-6.36) for ASD and PSD respectively. The results also had sex differences and the statistical significance was only observed in male ASD and female PDA. The ORs of T allele carriers were 2.29 (95% CI = 1.08-4.92) and 1.88 (95% CI = 1.02-3.47) compared with C allele for the occurrences of ASD and PDA respectively. The analysis of parents genotype showed that the OR of TT mothers was 2.31 (95% CI = 0.96-5.59, P < 0.05) compared with (CC + CT) for the occurrence of PDA in offspring. So this study could give a clue that MTHFR C677T locus variation was related with occurrence of ASD and PDA, and the carriers of TT genotype and T allele had higher risk of diseases. The mother carrying TT genotype was associated with occurrence of PDA in offspring.

The impact of plasma folate levels of mothers and newborns on intrauterine growth retardation and birth weight

Folate plays an important role in the genomic stability of human cells. In our studies of the impact of environmental pollution on human health, we have found that air pollution can affect pregnancy outcome. As it may be also affected by nutrition, we examined the effect of plasma folate levels of mothers and newborns on intrauterine growth retardation (IUGR) and birth weight (BW) in cohorts from Prague (N=319) and Teplice (N=444). The lower plasma levels (<6.1 nmol/L) were observed in 7.1% of mothers in Prague, and in 9.6% of mothers in Teplice. The higher plasma levels (>36.5 nmol/L) were observed in 28.4% of mothers in Prague, and in 15.7% of mothers in Teplice. The higher plasma levels were observed in 75.4% of newborns in Prague, and 73.2% of newborns in Teplice. When comparing maternal high versus low folate plasma levels and IUGR by logistic regression, the risk of IUGR was significantly decreased for European cohort (according to ethnicity) with gestation age >36 weeks [N=536, OR=0.44, P=0.026], and even more pronounced in the group of European smokers [N=157, OR=0.14, P=0.015]. Using multiple regression analysis, plasma folate levels of mothers and newborns significantly affected the birth weight of newborns of smoking mothers (P<0.05). The obtained results seem to indicate a positive effect of folate on pregnancy outcome, especially its potential to decrease the risk of IUGR in European population and lower birth weight in smoking European mothers. It would be warranted to study the effect of folate levels on pregnancy outcomes in the relationship to different environmental pollution and life styles of mothers.

Congenital structural anomalies in offspring of women with epilepsy—a population-based cohort study in Finland

BACKGROUND

Offspring of women with epilepsy may have an increased risk for congenital malformations, probably attributable to maternal antiepileptic medication. We conducted this population-based study to obtain valid and accurate estimates on major congenital malformations in the offspring of women with epilepsy, based on a large and representative patient cohort.

METHODS

We identified all women (n = 6,535) entitled to full reimbursement for antiepileptic medication indicated for epilepsy for the first time between 1985 and 1994 from the Social Insurance Institution of Finland database. A reference cohort (n = 14,704) was identified from the Finnish Population Register Centre. Information on children born between 1993 and 2000 (patient cohort, n = 2,162; reference cohort, n = 5,413) was obtained from the Medical Birth Register. Information on children born with malformation (patient cohort, n = 116; reference cohort, n = 151) was obtained from the Finnish Register of Congenital Malformations.

RESULTS

The prevalence of major malformation was 54/1,000 births among patients with epilepsy and 28/1,000 births among mothers without epilepsy, corresponding to a 2-fold overall risk for malformation in the offspring of women with epilepsy. The risk for spina bifida [odds ratio (OR) = 11.3, 95% confidence interval (CI) 2.34-108] and congenital anomalies of genital organs (OR = 8.38, 95% CI 2.15-47.4) was substantially elevated in the offspring of mothers with epilepsy.

CONCLUSIONS

The absolute excess in the prevalence of major malformations was 26/1,000 births in the offspring of mothers with epilepsy in relation to the offspring of reference mothers. The highest relative risk was observed in spina bifida and congenital anomalies of genital organs. However, these malformations cover only a small proportion of all major malformations.

A decreasing rate of neural tube defects following the recommendations for periconceptional folic acid supplementation

BACKGROUND/AIM

Neural tube defects (NTDs) are the most common birth defects, resulting in severe mortality and morbidity. In 1995, the supplementation of folic acid periconceptionally was officially recommended in Germany. The impact of the recommendations on the rate of NTDs was assessed.

METHODS

An active surveillance system was established in the northern Rhine area. From 1996, all departments of obstetrics were asked to report cases of NTDs in all abortions, live births and stillbirths. Compliance with the recommendations was evaluated in a sample of mothers who delivered at the Department of Obstetrics of Düsseldorf University in 2001.

RESULTS

From 1996-2003, 520 NTDs were reported. Compared to the rate of NTDs in 1996 (10.5/10,000), the average incidence in the years 1997 to 2003 dropped (6.8/10,000). The intake of folic acid, as recommended, was low among the general population (21.1%).

CONCLUSION

Active surveillance data on the rate of NTDs are compatible with the maximum decrease of about 20% to be expected from data on the implementation of the recommendations. A much greater decrease in NTDs should be the challenge for the future.

Reevaluating the benefits of folic acid fortification in the United States: economic analysis, regulation, and public health

Before a 1996 US regulation requiring fortification of enriched cereal-grain products with folic acid, 3 economic evaluations projected net economic benefits or cost savings of folic acid fortification resulting from the prevention of pregnancies affected by a neural tube defect. Because the observed decline in neural tube defect rates is greater than was forecast before fortification, the economic gains are correspondingly larger. Applying both cost-benefit and cost-effectiveness analytic techniques, we estimated that folic acid fortification is associated with annual economic benefit of 312 million dollars to 425 million dollars. The cost savings (net reduction in direct costs) were estimated to be in the range of 88 million dollars to 145 million dollars per year.

Management of epilepsy in women

There are many aspects to the management of epilepsy in women related to their role in reproduction. Some of these need to be considered in adolescents, some are related to pregnancy, concerning both the mother and her infant, and others with the menstrual cycle and the menopause. This review considers contraception, fertility, teratogenicity, and the use of folic acid. It also discusses the special investigations in pregnancy, hyperemesis, the effect of pregnancy on the control of epilepsy, the effect of seizures on the fetus, a first fit in pregnancy, pseudoseizures, seizures during delivery, vitamin K, breast feeding, postpartum maternal epilepsy, hereditary risks, counselling, catamenial epilepsy, the menopause, and bone density.

Folates en période péri-conceptionnelle et prévention du risque de fente orofaciale : rôle des apports alimentaires en France

BACKGROUND

Orofacial clefts are among the most frequent congenital malformations at birth with a prevalence of 1 in 700 births in Europe. The implication of environmental factors in their etiology has been demonstrated. The role of folic acid, or folates, in the prevention of orofacial clefts is still debated although its efficacy has been demonstrated for the prevention of neural tube defects.

METHODS

A case-control study was conducted in 7 hospitals in 4 centers in France. Cases (N=240) were children with non-syndromic orofacial cleft referred to one of the study hospitals for initial surgical repair in 1998 and 1999. Controls (N=236) matched for gender, geographic origin, and age were chosen in paediatric departments of the same hospitals. Usual dietary intake of folates was estimated using a food frequency questionnaire submitted to the mother at hospital. During the same interview, data on sociodemographic characteristics, medical and obstetrical history, tobacco and alcohol consumption, and vitamin supplements, were obtained. Odds ratios associated with quintiles of dietary intake of folates were estimated using logistic regression adjusting for known confounders.

RESULTS

A significant dose-response relationship between the risk of orofacial clefts and a decrease in the intake of folates from diet was found, stronger for cleft palate without cleft lip. Only few women (<1%) declared having taken vitamin supplements containing folic acid when planning their pregnancy.

CONCLUSION

Our study further suggests that folates are useful for the prevention of orofacial clefts during the periconceptual period. In our study, the estimated average daily intake of folates (270 microg/day) was below French national recommendations for the prevention of neural tube defects (400 microg/day). Since those insufficient folate intakes during the periconceptual period are not presently met by vitamin supplementation, the solution may come from the food fortification program proposed and implemented by the National Agency for Food Safety (AFSSA).

Avaliação de campanhas de saúde com ênfase na sífilis congênita: uma revisão sistemática

Campanhas têm sido instrumentos de políticas públicas de saúde, freqüentemente utilizadas no Brasil para esclarecer, motivar ou conseguir o apoio da população e/ou dos profissionais de saúde, em ações relevantes para a saúde pública. Esta revisão procurou levantar subsídios para a avaliação de campanhas de saúde, particularizando-se as metodologias utilizadas, tendo em vista a avaliação de campanhas dirigidas ao controle da sífilis congênita. Os conjuntos de palavras-chave utilizados foram "sífilis congênita + avaliação"; "campanhas de saúde + avaliação" e, "campanha + saúde + avaliação". As bases de dados pesquisadas foram a Medline (Medical Literature Analysis and Retrieval System Online) da National Library of Medicine (EUA), a LILACS (Literatura Latino-Americana e do Caribe em Ciências da Saúde) e da PAHO (Pan-American Health Organization), no período de 1980 e 2003. Foram incluídos 37 artigos nessa revisão, sendo 15 referentes à sífilis congênita e avaliação e 22 à campanha de saúde e avaliação. A revisão realizada mostrou que existe um espaço a ser preenchido neste campo, principalmente no que se refere à construção metodológica. Apesar da palavra avaliação constar nesses vários artigos, a fundamentação teórica encontrada não foi totalmente condizente com as propostas apresentadas.

Decline in the prevalence of spina bifida and anencephaly by race/ethnicity: 1995-2002

OBJECTIVE

In an effort to reduce the occurrence of neural tube defects (NTDs), folic acid fortification of US enriched grain products was authorized by the Food and Drug Administration in March 1996 and required by January 1998. Fortification has been shown to result in an important decline in the prevalence of spina bifida and anencephaly in the general US population; however, fortification's impact on specific racial/ethnic groups has not been well described. We sought to characterize the decline in the prevalence of spina bifida and anencephaly among specific racial/ethnic groups during the transition to mandatory folic acid fortification in the United States.

METHODS

Data from 21 population-based birth defects surveillance systems were used to examine trends in prevalence of spina bifida and anencephaly for specific racial/ethnic groups for the years 1995-2002. These years were divided into 3 periods: prefortification, optional fortification, and mandatory fortification. Race/ethnicity was defined as Hispanic, non-Hispanic white, and non-Hispanic black. Prevalence ratios were calculated for each racial/ethnic group by dividing the prevalence from the mandatory fortification period by the prevalence in the prefortification period.

RESULTS

The study included data on 4468 cases of spina bifida and 2625 cases of anencephaly. The prevalence of spina bifida and anencephaly was highest among Hispanic births, followed by non-Hispanic white births, with the lowest prevalence among non-Hispanic black births. Significant declines in spina bifida and anencephaly were observed among Hispanic births and non-Hispanic white births. The prevalence ratio for non-Hispanic black births was of borderline significance for spina bifida and was not significant for anencephaly.

CONCLUSIONS

The results of this study suggest that folic acid fortification is associated with significant decreases in the prevalence of spina bifida and anencephaly among non-Hispanic white and Hispanic births. The magnitude of the reduction was similar between these 2 groups and was more pronounced for spina bifida than for anencephaly. The decline in the prevalence of spina bifida and anencephaly among non-Hispanic black births did not reach statistical significance. Efforts to increase folic acid consumption for the prevention of NTDs in pregnancies among women of all races/ethnicities should be continued, and studies to identify and elucidate other risk factors for NTDs are warranted.

Health state preference scores of children with spina bifida and their caregivers

Cost-effectiveness evaluations of interventions to prevent or treat spina bifida require quality of life information measured as preference scores. Preference scores of caregivers also may be relevant. This study tested whether the preference scores of children with spina bifida and their caregivers would decrease as disability in the child increased. Families of children aged 0-17 with spina bifida (N = 98) were identified using a birth defect surveillance system in the state of Arkansas. Primary caregivers of children with spina bifida identified other families with an unaffected child (N = 49). Preference scores for child health states were determined using the Health Utilities Index--Mark 2 (HUI2). Caregiver preference scores were determined using the Quality of Well-Being (QWB) scale. Children with spina bifida were categorized into three disability levels according to the location of the child's lesion. Mean preference scores declined for both affected children and the primary caregiver as disability in the child increased. In multivariate analysis, the preference score of the child was a significant and positive predictor of the primary caregiver's preference score. A more modest association was found for caregiver health preference scores by lesion location. The findings can inform cost-effectiveness evaluations of interventions to treat or prevent spina bifida.

Reported multivitamin consumption and the occurrence of multiple congenital anomalies

The purpose of this case-control study was to determine whether multivitamin use is associated with the occurrence of multiple congenital anomalies (MCA). MCA case-infants were infants with two or more major birth defects affecting at least two different organ systems, with no recognized chromosome abnormality or single gene disorder. Control-infants were a random sample of live births with no major birth defects from the same population (metropolitan Atlanta) and time period (1993-1997) as the case-infants. Exposure to multivitamins, cereals, and supplements was ascertained from a maternal telephone interview and classified based on folic acid content. We compared women who used multivitamins three or more times per week with women who were not exposed to vitamins/cereals/supplements during the periconceptional period (3 months before pregnancy through the first trimester), adjusting for maternal age, education, race/ethnicity, first degree family history of a major birth defect, pre-pregnancy maternal body mass index, gravidity, and first trimester alcohol use and cigarette smoking. Periconceptional multivitamin use was associated with MCA among all infants (adjusted odds ratio [aOR]=2.4, 95% confidence interval [CI] 0.9-6.7), and especially when analysis was limited to those with no family history of major defects (aOR=4.0, 95% CI 1.3-12.8). MCA-infants with urinary obstructive defects were more common among multivitamin-exposed infants than among unexposed infants, but this defect did not occur within a consistent pattern of defects. While these findings provide some support for one previous study, the interpretation remains unclear given the proven protective effect of multivitamins containing folic acid on isolated neural tube defects and possibly other types of defects.

Preconception care by family physicians and general practitioners in Japan

BACKGROUND

Preconception care provided by family physicians/general practitioners (FP/GPs) can provide predictable benefits to mothers and infants. The objective of this study was to elucidate knowledge of, attitudes about, and practices of preconception care by FP/GPs in Japan.

METHODS

A survey was distributed to physician members of the Japanese Academy of Family Medicine. The questionnaire addressed experiences of preconception education in medical school and residency, frequency of preconception care in clinical practice, attitudes about providing preconception care, and perceived need for preconception education to medical students and residents.

RESULTS

Two hundred and sixty-eight of 347 (77%) eligible physicians responded. The most common education they reported receiving was about smoking cessation (71%), and the least was about folic acid supplementation (12%). Many participants reported providing smoking cessation in their practice (60%), though only about one third of respondents advise restricting alcohol intake. Few reported advising calcium supplementation (10%) or folic acid supplementation (4%). About 70% reported their willingness to provide preconception care. Almost all participants believe medical students and residents should have education about preconception care.

CONCLUSION

FP/GPs in Japan report little training in preconception care and few currently provide it. With training, most participants are willing to provide preconception care themselves and think medical students and residents should receive this education.

Embryology of neural tube development

Neurulation is the process of forming the neural tube, which will become the brain and spinal cord. This article reviews the various cellular processes involved in neurulation and discusses possible roles of folate in this process.

Folic acid supplementation and the occurrence of congenital heart defects, orofacial clefts, multiple births, and miscarriage

Key research findings relative to the question of whether maternal use of folic acid before and during pregnancy reduces the chance that offspring will be born with a congenital heart defect or an orofacial cleft are reviewed in this paper. Observational studies in general support an association between maternal use of multivitamins containing folic acid and a reduction in the occurrence of congenital heart defects and orofacial clefts. Results from one randomized controlled trial (RCT) provide the strongest evidence that multivitamins prevent congenital heart defects, but this RCT did not provide evidence that multivitamins prevent orofacial clefts. In addition, most observational and interventional studies are not designed to detect an independent effect from folic acid. Early studies suggested that periconceptional multivitamin use was associated with an increased occurrence of both miscarriages and multiple births, which has resulted in a great deal of controversy about the safety of folic acid use during pregnancy. We also review reports that were designed to answer these questions with more definitive data. When more substantial evidence about the effect of periconceptional folic acid on the occurrence of congenital heart defects and orofacial clefts is reported, we will have additional support for promoting folic acid intervention programs. All women capable of becoming pregnant should continue to consume 400 mug/d of folic acid in addition to a healthy diet as advised.

Hungarian cohort-controlled trial of periconceptional multivitamin supplementation shows a reduction in certain congenital abnormalities

BACKGROUND

The 1984-1991 Hungarian randomized controlled trial (RCT) of periconceptional multivitamin supplementation containing folic acid (0.8 mg) showed a significant reduction in the first occurrence of neural tube defects (NTDs), and of urinary tract and cardiovascular abnormalities, but no reduction in orofacial clefts. A controlled cohort trial was designed to confirm or deny these results.

METHODS

Supplemented women were recruited from the Hungarian Periconceptional Service using the same multivitamin as the Hungarian RCT. Unsupplemented pregnant women were recruited in the standard regional antenatal care clinics and were matched to each supplemented pregnant woman on the basis of age, socioeconomic status, place of residence, and year of pregnancy.

RESULTS

A total of 3056 informative offspring were evaluated in each cohort. The occurrence of congenital cardiovascular malformations (31 vs. 50) was reduced (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.38-0.96) in the supplemented cohort, accounted for mainly by ventricular septal defects (5 vs. 19; OR, 0.26; 95% CI, 0.09-0.72). There was no significant difference (14 vs. 19) in the occurrence of urinary tract defects between the two cohorts, but stenosis/atresia of pelvic-ureteric junction (2 vs. 13) showed a significant reduction (OR, 0.19; 95% CI, 0.04-0.86). The protective effect of the folic acid-containing multivitamin for NTDs (one offspring in the supplemented vs. nine in the unsupplemented cohort) was confirmed (OR, 0.11; 95% CI, 0.01-0.91). There was, however, no protective effect on orofacial clefts or on multiple congenital abnormalities.

CONCLUSIONS

The results of this cohort-controlled trial support the findings of the previous Hungarian RCT. The primary prevention of some major structural birth defects by multivitamins containing folic acid or by folic acid has great public health importance.

Developmental consequences of in utero sodium arsenate exposure in mice with folate transport deficiencies

Previous studies have demonstrated that mice lacking a functional folate binding protein 2 gene (Folbp2-/-) were significantly more sensitive to in utero arsenic exposure than were the wild-type mice similarly exposed. When these mice were fed a folate-deficient diet, the embryotoxic effect of arsenate was further exacerbated. Contrary to expectations, studies on 24-h urinary speciation of sodium arsenate did not demonstrate any significant difference in arsenic biotransformation between Folbp2-/- and Folbp2+/+ mice. To better understand the influence of folate pathway genes on arsenic embryotoxicity, the present investigation utilized transgenic mice with disrupted folate binding protein 1 (Folbp1) and reduced folate carrier (RFC) genes. Because complete inactivation of Folbp1 and RFC genes results in embryonic lethality, we used heterozygous animals. Overall, no RFC genotype-related differences in embryonic susceptibility to arsenic exposure were observed. Embryonic lethality and neural tube defect (NTD) frequency in Folbp1 mice was dose-dependent and differed from the RFC mice; however, no genotype-related differences were observed. The RFC heterozygotes tended to have higher plasma levels of S-adenosylhomocysteine (SAH) than did the wild-type controls, although this effect was not robust. It is concluded that genetic modifications at the Folbp1 and RFC loci confers no particular sensitivity to arsenic toxicity compared to wild-type controls, thus disproving the working hypothesis that decreased methylating capacity of the genetically modified mice would put them at increased risk for arsenic-induced reproductive toxicity.