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

Facts and Recommendations about Total Homocysteine Determinations: An Expert Opinion

Background: Measurement of plasma total homocysteine has become common as new methods have been introduced. A wide range of disorders are associated with increased concentrations of total homocysteine. The purpose of this review is to provide an international expert opinion on the practical aspects of total homocysteine determinations in clinical practice and in the research setting and on the relevance of total homocysteine measurements as diagnostic or screening tests in several target populations.

Methods: Published data available on Medline were used as the basis for the recommendations. Drafts of the recommendations were critically discussed at meetings over a period of 3 years.

Outcome: This review is divided into two sections: (a) determination of homocysteine (methods and their performance, sample collection and handling, biological determinants, reference intervals, within-person variability, and methionine loading test); and (b) risk assessment and disease diagnosis (homocystinuria, folate and cobalamin deficiencies, cardiovascular disease, renal failure, psychiatric disorders and cognitive impairment, pregnancy complications and birth defects, and screening of elderly and newborns). Each of these subsections concludes with a separate series of recommendations to assist the clinician and the research scientist in making informed decisions. The review concludes with a list of unresolved questions.

Vitamin supplements and the risk for congenital anomalies other than neural tube defects

Randomized trials, supported by many observational studies, have shown that periconceptional use of folic acid, alone or in multivitamin supplements, is effective for the primary prevention of neural tube defects (NTDs). Whether this is true also for other congenital anomalies is a complex issue and the focus of this review. It is useful to consider the evidence not only for specific birth defects separately but, importantly, also for all birth defects combined. For the latter, the Hungarian randomized clinical trial indicated, for periconceptional multivitamin use, a reduction in the risk for all birth defects (odds ratio (OR) = 0.53, 95% confidence interval (CI) = 0.35-0.70), even after excluding NTDs (OR = 0.53, 95% CI = 0.38-0.75). The Atlanta population-based case-control study, the only large observational study to date on all major birth defects, also found a significant risk reduction for all birth defects (OR = 0.80, 95% CI = 0.69-0.93) even after excluding NTDs (OR = 0.84, 95% CI = 0.72-0.97). These and other studies also evaluated specific anomalies, including those of the heart, limb, and urinary tract, as well as orofacial clefts, omphalocele, and imperforate anus. For cardiovascular anomalies, two studies were negative, whereas three, including the randomized clinical trial, suggest a possible 25-50% overall risk reduction, more marked for some conotruncal and septal defects. For orofacial clefts, six of seven case-control studies suggest an apparent reduced risk, which could vary by cleft type and perhaps, according to some investigators, by pill dosage. For limb deficiencies, three case-control studies and the randomized trial estimated approximately a 50% reduced risk. For urinary tract defects, three case-control studies and the randomized trial reported reduced risks, as did one study of nonsyndromic omphalocele. All these studies examined multivitamin supplement use. With respect to folic acid alone, a reduced rate of imperforate anus was observed among folic acid users in China. We discuss key gaps in knowledge, possible avenues for future research, and counseling issues for families concerned about occurrence or recurrence of these birth defects.

Birth defects in Arkansas: Is folic acid fortification making a difference?

BACKGROUND

Since 1998, fortification of grain products with folic acid has been mandated in the United States, in an effort to reduce the prevalence of neural tube defects (NTDs). Published reports have shown a reduction in the prevalence of spina bifida since fortification was mandated, but no published studies have reported a reduction in birth defects, other than NTDs, that are postulated to be associated with folic acid deficiency. This study was performed to determine if fortification has reduced the prevalence of NTDs and other birth defects in Arkansas.

METHODS

Using data from the Arkansas Reproductive Health Monitoring System, prevalences were computed for thirteen specific birth defects with prior evidence supporting a protective effect of folic acid or multivitamins. Prevalences were calculated using data for live births to Arkansas residents for 1993-2000. Exposure to folic acid fortification was classified by birth year as "pre-fortification" (1993-1995), "transition" (1996-1998) or "post-fortification" (1999-2000). Logistic regression analysis was used to compute crude and adjusted prevalence odds ratios comparing the identified time periods.

RESULTS

Prevalences decreased between the pre- and post-fortification periods for spina bifida, orofacial clefts, limb reduction defects, omphalocele, and Down syndrome, but only the decrease in spina bifida was statistically significant (prevalence odds ratio 0.56; 95% confidence interval, 0.37, 0.83).

CONCLUSION

In Arkansas, the prevalence of spina bifida has decreased since folic acid fortification of foods was implemented. Similar studies by other birth defects surveillance systems are needed to confirm a preventive effect of fortification for malformations other than spina bifida.

The primary prevention of birth defects: Multivitamins or folic acid?

Periconceptional use of folic acid alone or in multivitamin supplements is effective for the primary prevention of neural-tube defects. The Hungarian randomized and two-cohort controlled trials showed that periconceptional multivitamin supplementation can reduce the occurrence of some other structural birth defects, i.e. congenital abnormalities. These findings were supported by many, but not all observational studies. Recently there have been two main debated questions. The first one is whether the use of folic acid alone or folic acid-containing multivitamins is better. The second one is connected with the dilemma of whether high dose of folic acid (e.g. 5 mg) might be better than a daily multivitamin with 0.4 - 0.8 mg of folic acid. Comparison of the pooled data of two Hungarian trials using a multivitamin containing 0.8 mg folic acid and the data of the Hungarian Case-Control Surveillance of Congenital Abnormalities using high dose of folic acid seemed to be appropriate to answer these questions. Multivitamins containing 0.4 - 0.8 mg of folic acid were more effective for the reduction of neural-tube defects than high dose of folic acid. Both multivitamins and folic acid can prevent some part of congenital cardiovascular malformations. Only multivitamins were able to reduce the prevalence at birth of obstructive defects of urinary tract, limb deficiencies and congenital pyloric stenosis. However, folic acid was effective in preventing some part of rectal/anal stenosis/atresia, and high dose of folic acid had effect in preventing some orofacial clefts. The findings are consistent that periconceptional multivitamin and folic acid supplementation reduce the overall occurrence of congenital abnormalities in addition to the demonstrated effect on neural-tube defects.

Valproate-induced neural tube defects in folate-binding protein-2 (Folbp2) knockout mice

BACKGROUND

Folate is an important B vitamin that is transported into cells by way of folate-binding proteins and transporters. Folate-binding protein-2 nullizygous (Folbp2(-/-)) mice develop normally; however, we have found them to be more susceptible to the teratogenic effects of arsenate exposure than wild-type control mice.

METHODS

In the current study, we wanted to extend our findings and test the hypothesis that Folbp2(-/-) mice are more susceptible to the teratogenic effects of valproic acid (VPA), a commonly used antiepileptic drug that is known to induce neural tube defects (NTDs) in both humans and laboratory animals.

RESULTS

Folbp2(-/-) mice had higher VPA-induced frequencies of embryonic lethality and exencephaly than did the wild-type control mice during folate supplementation and a control diet, respectively. All other differences in response between the two genotypes were short of reaching statistical significance. Folate supplementation of wild-type, but not Folbp2(-/-) dams reduced embryonic lethality of VPA-treated wild-type embryos compared to the folate-deficient diet.

CONCLUSIONS

Unlike our previous findings with arsenate, enhanced susceptibility of Folbp2(-/-) mice to in utero VPA exposure was demonstrated in some dietary folate regimens. Thus, our data indicate a relatively frail relationship between Folbp2 and VPA-induced NTDs.

Folic Acid Awareness in Michigan, 1996–1999

OBJECTIVE

To evaluate the prevalence and trend of folic acid awareness among Michigan mothers during 1996-1999 and to identify maternal characteristics predictive of folic acid awareness.

METHODS

We analyzed data from the Michigan Pregnancy Risk Assessment Monitoring System, a population-based survey of women with recent live births. A positive response to the question, "Before you became pregnant, did you know that folic acid could help prevent some birth defects?" was used as an indicator of folic acid awareness. Logistic regression was used to evaluate trends in folic acid awareness prevalence and the association between folic acid awareness and certain maternal characteristics.

RESULTS

Of the women invited to participate, 7252 responded (67.3%). Overall, folic acid awareness increased from 1996 to 1999 (60.3-71.4%; P < .001). However, folic acid awareness decreased for women with no high school education from 1997 to 1999 (59.3-13.8%, P = .05). In addition, folic acid awareness was lower among black women (adjusted odds ratio [OR] 0.43; 95% confidence interval [CI] 0.4, 0.5, versus other races), women with unplanned pregnancies (adjusted OR 0.6; 95% CI 0.5, 0.8, versus those with planned pregnancies), and those with no high school education (adjusted OR 0.08; 95% CI 0.03, 0.2, versus women with college education).

CONCLUSION

Although folic acid awareness has increased among Michigan mothers overall during 1996-1999, it has decreased among women with less than a high school education, and substantial gaps exist among socioeconomic subgroups. Continued efforts are needed to improve folic acid awareness and consumption of folic acid among women of reproductive age, with special attention focused on populations experiencing gaps or declines in folic acid awareness.

Bioaccessibility of Folic Acid and (6S)-5-Methyltetrahydrofolate Decreases after the Addition of Folate-Binding Protein to Yogurt as Studied in a Dynamic In Vitro Gastrointestinal Model

Milk products are only moderate sources of folate. Nevertheless, they are of interest due to their content of folate-binding proteins (FBP), which in some studies have been reported to increase folate bioavailability. The effect of FBP on folate bioavailability has been widely discussed. The aim of this study was to investigate the bioaccessibility of folic acid and (6S)-5-methyltetrahydrofolate (5-CH3-H4folate) from fortified yogurt using a dynamic in vitro gastrointestinal model (TIM). In addition, the effect of FBP on folate bioaccessibility and the stability of FBP added to yogurt during gastrointestinal passage were investigated. Folate bioaccessibility was 82% from yogurt fortified with folic acid and 5-CH3-H4folate. The addition of FBP to yogurt decreased (P < 0.05) folate bioaccessibility. The lowering effect of FBP was more pronounced in yogurt fortified with folic acid (34% folate bioaccessibility) than from yogurt fortified with 5-CH3-H4folate (57% folate bioaccessibility). After gastrointestinal passage, 17% of the FBP in yogurt fortified with 5-CH3-H4folate and 34% of the FBP in yogurt fortified with folic acid were recovered. No difference in folate bioaccessibility was found between folate-fortified yogurt and folate-fortified pasteurized milk (P = 0.10), whereas the lowering effect of FBP was (P < 0.05) greater in yogurt compared with pasteurized milk. In conclusion, based on the high bioaccessibility of folic acid and 5-CH3-H4folate, yogurt without active FBP can be considered to be an appropriate food matrix for folate fortification.

The Use of Folic Acid for the Prevention of Neural Tube Defects and Other Congenital Anomalies

OBJECTIVE

To provide information regarding the use of folic acid for the prevention of neural tube defects (NTDs) and other congenital anomalies, in order that physicians, midwives, nurses, and other health-care workers can assist in the education of women in the preconception phase of their health care. OPTION: Folic acid supplementation is problematic, since 50% of pregnancies are unplanned and the health status of women may not be optimal.

OUTCOMES

Folic acid supplementation has been proven to decrease or minimize specific birth defects.

EVIDENCE

A systematic review of the literature, including review and peer-reviewed articles, government publications, the previous Society of Obstetricians and Gynaecologists of Canada (SOGC) Policy Statement of March 1993, and statements from the American College of Obstetrics and Gynecology, was used to develop a new clinical practice guideline for the SOGC.

VALUES

Peer-review process within the committee structure.

BENEFITS, HARMS, AND COSTS

The benefit is reduced lethal and severe morbidity birth defects and the harm is minimal. The personal cost is of vitamin supplementation on a daily basis and eating a healthy diet.

RECOMMENDATIONS

1. Women in the reproductive age group should be advised about the benefits of folic acid supplementation during wellness visits (birth control renewal, Pap testing, yearly examination), especially if pregnancy is contemplated. (III-A) 2. Women should be advised to maintain a healthy nutritional diet, as recommended in Canada's Food Guide to Healthy Eating (good or excellent sources of folic acid: broccoli, spinach, peas, Brussels sprouts, corn, beans, lentils, oranges). (III-A) 3. Women who could become pregnant should be advised to take a multivitamin containing 0.4 mg to 1.0 mg of folic acid daily. (II-1A) 4. Women taking a multivitamin with folic acid supplement should be advised not to take more than 1 daily dose of vitamin supplement, as indicated on the product label. (II-2A) 5. Women in intermediate- to high-risk categories for NTDs (NTD-affected previous pregnancy, family history, insulin-dependent diabetes, epilepsy treatment with valproic acid or carbamazepine) should be advised that high-dose folic acid (4.0 mg-5.0 mg daily) supplementation is recommended. This should be taken as folic acid alone, not in a multivitamin format, due to risk of excessive intake of other vitamins such as vitamin A. (I-A) 6. The choice of a 5 mg folic acid daily dose for women considering a pregnancy should be made under medical supervision after minimizing the risk of undiagnosed vitamin B12 deficiency (hypersegmentation of polymorphonuclear cells, macrocystic indices, large ovalocytes, leukopenia, thrombocytopenia, markedly elevated lactate dehydrogenase level, confirmed red blood cell folate level). (II-2A) 7. Signs or symptoms of vitamin B12 deficiency should be considered before initiating folic acid supplementation of doses greater than 1.0 mg. (III-A) 8. A three-generation pedigree on the families of both the pregnant woman and the biological father should be obtained to identify increased risk for congenital birth defects (i.e., NTD, cardiac, chromosomal, genetic). (III-A) 9. Women who become pregnant should be advised of the availability of noninvasive screening tests and invasive diagnostic tests for congenital birth defects (including NTDs): maternal serum "triple marker screen" at 15 to 20 weeks, ultrasound at 16 to 20 weeks, and amniocentesis after 15 weeks of pregnancy if a positive screening test is present. (I-A) VALIDATION: This is a revision of a previous guideline and information from other consensus reviews from medical and government publications has been used.

Role of Folate in Colon Cancer Development and Progression

Folate, a water-soluble B vitamin and important cofactor in 1-carbon transfer, is an important nutritional factor that may modulate the development of colorectal cancer. Epidemiologic and clinical studies indicate that dietary folate intake and blood folate levels are inversely associated with colorectal cancer risk. Collectively, these studies suggest an approximately 40% reduction in the risk of colorectal cancer in individuals with the highest dietary folate intake compared with those with the lowest intake. Animal studies using chemical and genetically predisposed rodent models have provided considerable support for a causal relationship between folate depletion and colorectal carcinogenesis as well as a dose-dependent protective effect of folate supplementation. However, animal studies have also shown that the dose and timing of folate intervention are critical in providing safe and effective chemoprevention; exceptionally high supplemental folate levels and folate intervention after microscopic neoplastic foci are established in the colorectal mucosa promote rather than suppress colorectal carcinogenesis. These animal studies in conjunction with clinical observations suggest that folate possesses the dual modulatory effects on carcinogenesis depending on the timing and dose of folate intervention. Folate deficiency has an inhibitory effect whereas folate supplementation has a promoting effect on progression of established neoplasms. In contrast, folate deficiency in normal epithelial tissues appears to predispose them to neoplastic transformation, and modest levels of folate supplementation suppress the development of tumors in normal tissues. Notwithstanding the limitations associated with animal models, these animal studies suggest that the optimal timing and dose of folate intervention need to be established for safe and effective chemoprevention in humans.

Antagonism of Hypervitaminosis A-Induced Anterior Neural Tube Closure Defects with a Methyl-Donor Deficiency in Murine Whole-Embryo Culture

The interaction of a dietary excess of vitamin A (retinoid) and deficiency of methyl-donor compounds was examined in murine early-organogenesis embryonic development. Female mice were fed one of six diets from the time of vaginal plug detection until gestational d 8.0, when embryos were removed and grown in whole embryo culture for 46 h, using serum from rats fed the same diet for 36 d as the culture medium. The six diets were either methyl-donor deficient (designated -FCM: devoid of folic acid, choline and supplemental L-methionine, but having methionine as a component of the protein portion of the diet) or methyl-donor sufficient (designated +FCM: containing folic acid, choline and L-methionine supplementation), in combination with one of three concentrations of retinyl palmitate (0.016, 0.416 or 4.016 g/kg diet). The high dose of retinyl palmitate induced a failure of anterior neuropore closure and hypoplasia of the visceral arches, both of which were significantly ameliorated by simultaneous administration of the methyl-donor-deficient diet. The primary acidic retinoid detected in the rat serum was 9,13-di-cis-retinoic acid, although we hypothesize that teratogenic retinoids were formed by embryonic biotransformation of the retinyl esters to toxic metabolites. Biochemical measurements of metabolites in relevant pathways were performed. We propose that the amelioration of these malformations may be used to determine biochemical pathways critical for retinoid teratogenesis.

Preliminary data on changes in neural tube defect prevalence rates after folic acid fortification in South America

Several South American countries are fortifying wheat flour with folic acid. However, only Chile started in 2000 to add 2.2 mg/kg, providing 360 microg daily per capita, an acceptable dosage for preventing the occurrence of some neural tube defect (NTD) cases. ECLAMC (Spanish acronym for the Latin American Collaborative Study of Congenital Malformations) routinely monitoring birth defects in South America since 1976, surveyed the impact of this fortification. Data from 361,374 births occurred in 43 South American hospitals, distributed in five different countries, active throughout the 1999-2001 triennium, were selected from the ECLAMC network. Birth prevalence rates for three different congenital anomalies with similar expected prevalence rates, were surveyed by the Cumulative Sum Method (CUSUM) method. They were NTD, oral clefts (OC), and Down syndrome (DS). Expected values were derived from observations made in 1999, and CUSUM was applied to the consecutive series of 24 months covering years 2000 and 2001. Only one of three congenital anomaly types, NTDs, in only one of five sampled out countries, Chile, showed a significant decrease, of 31%, during the 2000-2001 biennium, corresponding to the birth of the periconceptionally fortified infants. The level of significance (P < 0.001) was reached in the 20th month after fortification started, corresponding to August 2001. This is the first observation of a significant decrease in the occurrence of NTD after folic acid food fortification in a population little influenced by confounders common in the developed world as pre-existing secular decreasing trends, and partially unregistered induced abortions.

Antibodies to folate receptors impair embryogenesis and fetal development in the rat

BACKGROUND

Folic acid (FA) supplementation reduces neural tube defects (NTDs) by 70%. However, the cause of most NTDs cannot be attributed to folate deficiency, to mutations of genes that encode folate pathway enzymes, and folate receptors (FRs) that mediate cellular folate uptake. Mouse embryos nullizygous for the ortholog of the FRalpha gene have lethal congenital abnormalities that are preventable by administration of folinic acid to the dams. To determine whether antibodies to FRs are similarly teratogenic, we studied a rat model.

METHODS

Immunohistochemistry with an antiserum to rat FRs was used to identify the receptors on reproductive tissues and embryos. Gestation day (GD) 8 rats received intraperitoneal injections of antiserum to the FRs, and their embryos were examined 2-9 days later. Some rats received pharmacologic doses of folinic acid or dexamethasone before the antiserum was administered.

RESULTS

The FRs are present on oocytes, the oviduct, and uterine epithelial cells, and in the embryo at all stages examined between GD4 and GD15. The antiserum has a dose-related effect on embryo viability and organogenesis. Folinic acid prevented teratogenicity resulting from smaller doses of antiserum, but not that caused by larger doses. Resorption of embryos with the larger doses of the antiserum was prevented by dexamethasone.

CONCLUSIONS

FRs are expressed on oocytes, epithelial cells of reproductive organs, and embryonic and extraembryonic tissues. Antiserum to FRs administered to pregnant rats causes embryonic damage. Embryo lethality with smaller doses of antiserum is preventable by administration of folinic acid, while larger doses cause embryo damage by immune-mediated cell lysis, which can be prevented by dexamethasone.

Maternal serum and amniotic fluid hydroxyproline levels in neural tube defects

OBJECTIVE

The present study was aimed to evaluate the alterations of maternal serum and amniotic fluid OH- proline levels in neural tube defects (NTD).

METHODS

38 patients and 23 control subjects were selected from the patients followed up by the Departments of Genetics and Antenatal Care, Zekai Tahir Burak Women's Health, Education and Research Hospital. Amnion fluid and blood samples were synchronously obtained from NTD and control subjects. OH-proline levels were detected spectrophotometrically.

RESULTS

Amniotic fluid OH-proline levels were found to be increased in NTD patients compared to control subjects (p < 0.05). There was no statistically significant difference in serum OH-proline levels between the groups.

CONCLUSION

The results showed an increase in amniotic fluid OH-proline levels in NTD compared to the control group. It may be suggested that the increased OH-proline levels reflect increased collagen turnover in NTD patients. Indeed, amniotic fluid OH-proline levels may be a candidate as an additional diagnostic parameter in NTD.

The Australian registry of anti-epileptic drugs in pregnancy: experience after 30 months

BACKGROUND

Most women with epilepsy need to take antiepileptic drugs (AEDs) in pregnancy to prevent the potentially harmful effects of seizures. Retrospective studies have demonstrated an increased chance of having a child with a birth defect (BD) in women with epilepsy taking AEDs. It is uncertain how much of this risk is directly caused by the AEDs and whether certain drugs or combinations are associated with a greater risk.

AIMS

To establish a register to evaluate prospectively the incidence of adverse pregnancy outcomes in women exposed to specific AEDs; to determine whether certain AEDs or combinations were associated with a greater risk; and to determine whether other factors influenced the risk.

METHODS

An Australia-wide, prospective, voluntary, telephone-interview based, observational register. Three groups of pregnant women were enrolled: those with epilepsy taking AEDs, those with epilepsy not taking AEDs, and those taking AEDs for a non-epileptic indication. The pregnancy outcomes were evaluated by follow-up interviews and by reference to hospital and treating doctors' records.

RESULTS

Over the first 30 months of the study (till December 2001) 334 eligible women were enrolled, with all states and territories being represented. Two hundred and ninety two pregnancies had been completed, of which 256 (88%) resulted in a healthy live birth, 19 (6.5%) a live birth with a birth defect, four an induced abortion because of a detected malformation on ultrasound, one premature labour with a stillbirth and 12 (4%) spontaneous abortions. Of the completed pregnancies, 269 were exposed to at least one AED during the first trimester. The incidence of birth defects in relation to specific AEDs was: valproate (16.7%), phenytoin (10.5%), lamotrigine (7.7%) and carbamazepine (3.3%), none of which was significantly different from that in women with epilepsy not taking an AED (4.3%, n.s.). The dose of valproate taken was higher in pregnancies with BD compared to those without (mean 2081 mg vs. 1149 mg, p<0.0001). The incidence of folate supplementation being taken prior to conception did not differ for pregnancy outcomes with or without BD (70% vs. 66%, n.s.).

CONCLUSIONS

The model for the Australian Pregnancy Register appears to be successful, with strong enrolment from all regions over the first 30 months. The study is prospective and includes reference to all new AEDs approved in Australia over the past decade. Analysis of the pregnancy outcomes to date may reveal early trends, but numbers are still to small for any definitive conclusions to be made regarding the relative risk in pregnancy of individual AEDs.

Neural tube defects: knowledge and preconceptional prevention practices in minority young women

OBJECTIVE

To assess 1) knowledge of neural tube defect (NTD) prevention by folic acid, 2) frequency of intake of multivitamins and folate- and folic acid-fortified food, and 3) factors associated with knowledge and prevention practices among sexually active minority adolescent and young adult women.

METHODS

Young minority women were enrolled in a folic acid program at 3 urban Houston, Texas, reproductive health clinics and assessed for NTD knowledge and preventive practices. A 3-month supply of multivitamins was also dispensed at enrollment. A 3-month program follow-up survey of a randomly selected sample at 2 sites was conducted.

RESULTS

Of 387 women (mean age: 18 +/- 1.9 years), 72% were black and 28% were Hispanic. At enrollment, clinics were a major source of information of NTD prevention (44%); 52% had heard of folic acid, 45% had heard of NTDs, and 50% had heard of birth defects prevention by multivitamins. Significantly more Hispanic than black young women had heard of NTDs (59% vs 39%). Pregnancy history, regular birth control use, and education level for age were independently associated with knowledge. In young women with low education level for age, regular birth control use was significantly associated with knowledge. At enrollment, daily multivitamin intake was very low (9%) and folate-rich foods were consumed in inadequate amounts. Adequate folate diet was not associated with knowledge. The program follow-up survey indicated that 88% to 92% had knowledge of NTDs and folic acid, and 67% reported taking a daily multivitamin.

CONCLUSIONS

Publicly funded clinics may be the only source of information on NTD prevention for many minority young women. Preliminary evidence suggests that a promotion program improves knowledge, and dispensing of multivitamins increases multivitamin use. However, clinicians in such programs need to reinforce daily adherence to multivitamins in young women.

Do multivitamin or folic acid supplements reduce the risk for congenital heart defects? Evidence and gaps

Congenital heart defects are among the most common congenital anomalies and are the leading cause of infant death due to congenital anomalies. Except for a few known measures, effective primary prevention is not yet feasible for most heart anomalies. Recent reports have associated the use of multivitamin supplements around the time of conception and during early pregnancy with a reduced risk for heart defects in the offspring. We review and discuss the evidence and suggest a framework for further investigation in this area.

Weekly high-dose folic Acid supplementation is effective in lowering serum homocysteine concentrations in women

AIMS

To compare the efficacy of a weekly high-dose (2,800 microg) folic acid supplement with a daily (400 microg) folic acid supplement in lowering homocysteine concentrations in healthy women of childbearing age.

METHODS

Free-living healthy women of childbearing age (n = 138) were randomized to receive a weekly (2,800 microg), a daily (400 microg) folic acid supplement, or placebo. Blood samples were collected at baseline and at 12 weeks and analyzed for serum homocysteine and erythrocyte folate.

RESULTS

At 12 weeks the mean (95% CI) serum homocysteine concentrations declined significantly (p < 0.05) in women receiving the daily [week 12 - baseline: -1.4 (-2.0, -0.70) micromol/l] and the weekly supplement [-1.3 (-2.1, -0.5) micromol/l] versus placebo [0.0 (-0.5, 0.5) micromol/l]. There was no significant difference between the two folate-treated groups (p > 0.05). At 12 weeks the mean erythrocyte folate concentration increased significantly in both supplemented groups versus placebo (p < 0.001). The increase in erythrocyte folate was significantly greater (p < 0.001) in the daily group than in the weekly group [451 (380, 521) vs. 288 (240, 335) nmol/l].

CONCLUSION

A weekly high-dose folic acid supplement was as effective as a daily supplement in lowering homocysteine concentrations in healthy women of childbearing age. Further study is needed to determine if weekly folic acid supplementation is effective in lowering homocysteine concentrations in populations with high homocysteine.

Epidemiology of neural tube defects

Neural tube defects (NTDs)-malformations secondary to abnormal neural tube closure between the third and fourth weeks of gestational age-have a complex and imperfectly understood etiology in which both genetic and environmental factors appear to be involved. A number of specific chromosomal or single-gene disorders, presumably not affected by environmental influences, are associated with the development of NTDs, but such syndromal cases account for a small proportion of NTDs in live-born infants. Analysis of recurrence patterns within families and of twin-concordance data provides evidence of a genetic influence in nonsyndromal cases, but factors such as socioeconomic status and geographic area (independent of race or ethnicity) are also associated with variations in the incidence of NTDs. The prevalence at birth of both anencephaly and spina bifida has decreased, but the advent of antenatal diagnosis and elective termination of affected pregnancies has undermined the reliability of birth prevalence rate as an estimate of incidence. Some occupational and other exposures, including maternal use of antiepileptic drugs (AEDs), are associated with increased risk for NTDs. Among women who have had an NTD-affected pregnancy, recurrence risk is markedly higher than the risk for a first NTD-affected pregnancy in the general population. There is strong evidence, overall, for a protective effect of adequate folate consumption. In some high-risk groups, however, such as women taking AEDs, folate supplementation has not been proven to reduce NTD risk.

Reduced-folate carrier (RFC) is expressed in placenta and yolk sac, as well as in cells of the developing forebrain, hindbrain, neural tube, craniofacial region, eye, limb buds and heart

BACKGROUND

Folate is essential for cellular proliferation and tissue regeneration. As mammalian cells cannot synthesize folates de novo, tightly regulated cellular uptake processes have evolved to sustain sufficient levels of intracellular tetrahydrofolate cofactors to support biosynthesis of purines, pyrimidines, and some amino acids (serine, methionine). Though reduced-folate carrier (RFC) is one of the major proteins mediating folate transport, knowledge of the developmental expression of RFC is lacking. We utilized in situ hybridization and immunolocalization to determine the developmental distribution of RFC message and protein, respectively.

RESULTS

In the mouse, RFC transcripts and protein are expressed in the E10.0 placenta and yolk sac. In the E9.0 to E11.5 mouse embryo RFC is widely detectable, with intense signal localized to cell populations in the neural tube, craniofacial region, limb buds and heart. During early development, RFC is expressed throughout the eye, but by E12.5, RFC protein becomes localized to the retinal pigment epithelium (RPE).

CONCLUSIONS

Clinical studies show a statistical decrease in the number of neural tube defects, craniofacial abnormalities, cardiovascular defects and limb abnormalities detected in offspring of female patients given supplementary folate during pregnancy. The mechanism, however, by which folate supplementation ameliorates the occurrence of developmental defects is unclear. The present work demonstrates that RFC is present in placenta and yolk sac and provides the first evidence that it is expressed in the neural tube, craniofacial region, limb buds and heart during organogenesis. These findings suggest that rapidly dividing cells in the developing neural tube, craniofacial region, limb buds and heart may be particularly susceptible to folate deficiency.

Periconceptional multivitamin folic acid use, dietary folate, total folate and risk of neural tube defects in South Carolina

PURPOSE

To investigate whether dietary folate or multivitamin folic acid taken 3 months before conception and during the first 3 months of pregnancy reduces the risk of isolated occurrent neural tube defect (NTD)-affected pregnancies.

METHODS

This population-based case control study conducted between 1992 and 1997 included 179 women with NTD-affected pregnancies and 288 randomly selected controls. Women completed a food frequency questionnaire and were interviewed about lifestyle behaviors, pregnancy histories and use of multivitamins.

RESULTS

Use of 0.4 mg or more of multivitamin folic acid at least 3 times per week during the periconceptional period showed no statistically significant reduction in NTD risk [adjusted odds ratio (AOR) = 0.55, 95% confidence interval (CI) = 025, 1.22]. After adjusting for covariates, protective effects for NTDs were observed at the highest quartiles of dietary folate and total folate (daily dietary folate plus daily multivitamin folic acid); the respective odds ratios were 0.40 (95% CI = 0.19, 0.84) and 0.35 (95% CI = 0.17, 0.72).

CONCLUSIONS

This study illustrates some of the difficulties in determining effects of folic acid and dietary folate in a population where the consumption of foods rich in folate and the use of multivitamins are increasing and the rate of NTDs is declining. Studies are needed to monitor future changes in folate levels and their effect on health.

A population-based birth defects surveillance system in the People's Republic of China

We describe a unique birth defects surveillance system in the People's Republic of China. The system was instituted in March 1992 as a component of an evaluation of the effectiveness of a public health campaign using periconceptional folic acid supplementation to prevent neural tube defects, and currently surveys birth cohorts of approximately 150 000 infants per year. Local health care providers collect information in the form of detailed written descriptions and photographs of affected infants. The system allows for detection of birth defects at the local level with later definitive classification and coding; however, information is limited to structural anomalies that are visible on physical examination. This birth defects surveillance system provides an extensive database of infants with major and minor external structural anomalies, including the unique feature of a photographic record for most cases. These data can be used for aetiological studies, descriptive epidemiology and identification of unusual trends.

Periconceptional use of folic acid supplements in Oslo

BACKGROUND

Periconceptional supplementation with folic acid has been shown to decrease the occurrence of neural tube defects (NTD). A daily supplement of 400 micro g folic acid from the month before pregnancy and the first 2 to 3 months of pregnancy is recommended in Norway. We wanted to evaluate the use of folic acid supplements among pregnant women in Oslo, and to explore demographic factors that were associated with periconceptional intake.

METHODS

All women attending antenatal ultrasound screening at the two main obstetric departments in Oslo during 3 months in 2001 were invited to answer questions regarding folic acid supplementation before and during their present pregnancy.

RESULTS

A total of 1541 women (91, 5%) participated in the study, of which 26% were nonwestern immigrants. Only 17% of all women had started the folic acid supplementation preconceptionally (22% of the nonimmigrant vs. 2% of the immigrant population). Folic acid had been used by 58% at some time during the present pregnancy (73% of the nonimmigrant vs. 19% of the immigrant population). Regression analysis demonstrated that the difference in periconceptional use of folic acid between the two population groups could not be explained by registered demographic factors other than immigrant status.

CONCLUSIONS

Most pregnant women in Oslo do not use folic acid as recommended and a dramatically low usage is seen among the immigrant population, indicating that more widespread information is necessary. Furthermore, fortification of cereals with folic acid should be considered to secure a sufficient intake of folic acid in all fertile women.

Folic acid supplements and fortification affect the risk for neural tube defects, vascular disease and cancer: evolving science

Folic acid supplements reduce the risk of neural tube defects and may be associated with reduced risk for vascular disease and cancer. Research data from both observational and controlled intervention studies provide strong support for the existing public health policies related to folic acid and neural tube defects. However, educational efforts to promote daily intake of folic acid supplements by women of reproductive age have not, in most cases, resulted in increased supplement use. In contrast, food fortification appears to be associated with a reduction in neural tube defects in the United States and Canada but is not practiced universally. The potential for folic acid supplements to reduce the incidence and severity of vascular disease and cancer is the focus of major research efforts including ongoing intervention studies.

Periconceptional folic acid use and the prevalence of neural tube defects in The Netherlands

OBJECTIVE

To study the effect of increased folic acid intake on the prevalence of neural tube defects (NTD) in The Netherlands.

STUDY DESIGN

Using the capture-recapture method, the prevalence of NTD was estimated on the basis of five different registries on births affected by NTD.

RESULTS

Total prevalence over the 1988-1998 period varied between 1.43 and 1.96 per 1000 live and still births. No decrease in total prevalence was found to have taken place during that period. Scrutiny of the last 2 years, 1997 and 1998, in which increased folic acid intake might be expected to have had an effect, did not give any indication that the prevalence of NTD was falling.

CONCLUSIONS

A decrease in the Dutch prevalence of NTD during the study period could not be demonstrated due to the relatively small number of women using folic acid periconceptionally. This does not mean automatically that periconceptional folic acid use is ineffective in reducing the Dutch prevalence of NTD. Further monitoring is needed.

The epidemiology of adverse pregnancy outcomes: an overview

This paper provides an overview of the occurrence, etiology and temporal trends of adverse pregnancy outcomes. Disparities between developed and developing countries are highlighted for maternal mortality, infant mortality, stillbirth and low birth weight. The higher rate of low birth weight in developing countries is primarily due to intrauterine growth restriction rather than preterm birth. Much of the excess intrauterine growth restriction is caused by short maternal stature, low prepregnancy body mass index and low gestational weight gain (due to low energy intake). No important contribution has been established for micronutrient intake, nor have different fetal growth trajectories been demonstrated to reflect the timing of exposure to nutritional or other etiologic factors. Infant mortality has declined substantially over time both in developed and developing countries despite no decline (and even an increase) in low birth weight. Several developed countries have reported a temporal increase in fetal growth in infants born at term, a reduction in stillbirth rates and prevention of neural tube defects. More progress is required, however, in understanding the etiology and prevention of preterm birth.

Frequency of Down's syndrome and neural-tube defects in the same family

BACKGROUND

There is evidence that some mothers of infants with Down's syndrome have abnormal metabolism of folate and methyl, as well as mutations in folate genes, which are features that are also seen in neural-tube defects (NTD). We therefore investigated whether Down's syndrome and NTD arise more often in the same family than would be expected from the incidence of each disorder considered separately.

METHODS

We studied two series of families using information obtained from medical records about maternal age, pregnancy outcome, congenital malformations, and karyotype: the first, 493 families from Israel who were at high risk of NTD (445 with a history of NTD and 48 with isolated hydrocephalus); and the second, 516 families from the Ukraine at high risk of Down's syndrome.

FINDINGS

In the families at risk of NTD, there were a total of 11 pregnancies affected by Down's syndrome in 1492 at-risk pregnancies (compared with 1.87 expected on the basis of maternal age), which was a significant increase (p<0.00001). In the families at risk of Down's syndrome, there were seven NTD pregnancies in 1847 at risk, compared with 1.37 expected (p<0.001).

INTERPRETATION

In this study, we provide direct evidence of a link between Down's syndrome and NTD. Folate supplementation before conception has the potential to reduce the frequency of Down's syndrome.

Decreasing prevalence of neural tube defects in Utah, 1985-2000

BACKGROUND

The Utah Birth Defect Network, a statewide surveillance program based in the Utah Department of Health, monitors the occurrence of all neural tube defects (NTDs). Retrospectively and prospectively population-based data was utilized to assess the trend in prevalence for NTDs in Utah from 1985-2000.

METHODS

The Utah Birth Defect Network (UBDN) has prospectively identified NTDs in Utah since 1994. NTD cases, including meningomyelocele, meningocele, anencephaly (including exencephaly), encephalocele and craniorachischisis, born to women who are residents of Utah at delivery are reviewed by a pediatric geneticist. All NTDs occurring from 1985-1993 were ascertained retrospectively and documented to be a case. NTDs from all pregnancy outcomes are included (live births, stillbirths and pregnancy terminations) during the entire study period.

RESULTS

NTDs in Utah have decreased significantly between 1985-2000 and remain at the lowest prevalence over the last three of those years. The most significant decrease was seen from 1993-2000. The downward trend was demonstrable for anencephaly and meningomyelocele but not for encephalocele. The proportion of NTDs diagnosed prenatally, as well as those pregnancies terminated after prenatal diagnosis have remained constant, without any evidence of an increasing trend since 1990. However, the proportion of pregnancy terminations occurring prior to twenty weeks gestation has increased significantly since 1990.

CONCLUSIONS

The reason for the observed decrease is not known but is likely the result of simultaneous prevention activities locally and nationally, the Utah population's propensity for vitamin and supplement consumption, and recent food fortification. The Centers for Disease Control and Prevention recommended in 1992 that all women in their childbearing years take folic acid daily. The Utah Folic Acid Educational Campaign targeted all women of childbearing years beginning in 1996 with this message. Additionally, fortification of grains was voluntary from 1996, became mandatory in 1998 at which point NTD prevalence declined to its lowest level. These factors may have collectively contributed to the reduction observed in NTD prevalence within Utah, demonstrating the positive impact of an important public health endeavor.

Diet quality and risk of neural tube defects

Many studies have examined the impact of single nutrients on neural tube defect (NTD) risk, particularly folate. The impact of dietary patterns or nutrients in combination has received much less attention. This study examines the association of diet quality with NTD risk, using food frequency data from a population-based case-control study of NTDs (n=454 cases and 462 controls). The diet quality score was based on low (<10th percentile among controls) versus high (>90th percentile) values for intakes of iron, vitamins B(6) and A, calcium, folate, and percentage of kilocalories from fat and from sweets (range=0-14). Women with a low score (i.e., <4, or <10th percentile) had an elevated risk of an NTD-affected pregnancy (odds ratio 1.6, 95% CI 1.0-2.6). Stratified analyses suggested that the effect may be restricted to certain groups of women who may be at greater nutritional risk (i.e., women who did not take vitamin supplements or regularly consume breakfast cereals before pregnancy).

Comparison of the effect of low-dose supplementation with L-5-methyltetrahydrofolate or folic acid on plasma homocysteine: a randomized placebo-controlled study

BACKGROUND

Food fortification with folic acid has been introduced in several countries for the prevention of neural tube defects. Fortification has lowered total homocysteine (tHcy) concentrations in the US population, a consequence that may have health benefits. However, folic acid fortification could mask vitamin B-12 deficiency. Synthetic L-5-methyltetrahydrofolate (L-MTHF) may be more appropriate than folic acid as a fortificant because it is unlikely to mask the hematologic indicators of vitamin B-12 deficiency.

OBJECTIVE

The objective of the study was to compare the effectiveness of 100 micro g folic acid/d with that of equimolar L-MTHF in lowering tHcy in healthy volunteers.

DESIGN

The study was designed as a 24-wk, randomized, placebo-controlled intervention. Free-living healthy volunteers (n = 167) were randomly assigned to receive a daily supplement containing folic acid (100 microg), L-MTHF (113 microg), or placebo. Blood collected at baseline and at 8, 16, and 24 wk was analyzed for tHcy, plasma folate, and red blood cell folate (RCF) concentrations.

RESULTS

At 24 wk, after adjustment for baseline values, mean (95% CI) tHcy was 14.6% (9.3, 19.5%) and 9.3% (3.7, 14.6%) lower, mean plasma folate was 34% (14, 56%) and 52% (30, 78%) higher, and mean RCF was 23% (12, 35%) and 31% (19, 44%) higher in the L-MTHF and folic acid groups, respectively, than in the placebo group. L-MTHF was more effective than was folic acid in lowering tHcy (P < 0.05). At 24 wk, the increases in plasma folate and RCF concentrations did not differ significantly between the 2 supplemented groups.

CONCLUSION

Low-dose L-MTHF is at least as effective as is folic acid in reducing tHcy concentrations in healthy persons.

Folate intake and the risk of neural tube defects: an estimation of dose-response

BACKGROUND

Studies have shown that folic acid supplementation in early pregnancy markedly reduces the risk of neural tube defects (NTDs). Investigation of the relation between relative dose of supplemental folic acid or total folate intake and NTD risk is limited.

METHODS

We used data from 23,228 women, predominantly from the northeastern United States, enrolled between October 1984 and June 1987 in a prospective study of early prenatal exposures and pregnancy outcomes. Diet and vitamin intake data were gathered in the early second trimester. NTDs were ascertained through prenatal testing and by report of the delivering physician. Data analyses included multiple logistic regression and restricted spline regression modeling.

RESULTS

For each additional 500 dietary folate equivalents consumed per day, the prevalence of NTDs decreased by 0.78 cases (95% confidence interval [CI] = 0.47-1.09) per 1,000 pregnancies. Compared with women having the lowest total folate intakes (0-149 folate equivalents per day), the prevalence of NTDs declined by 34%, 30%, 56% and 77% among the offspring of those women consuming 150-399, 400-799, 800-1199 and > or = 1200 folate equivalents per day, respectively (P-value for linear trend = 0.016).

CONCLUSIONS

Our results suggest that NTD risk declines markedly with modest increases of total folate in early pregnancy. Total folate dose, rather than supplemental folate alone, should be considered in formulating public health guidelines for NTD prevention.

[Prophylaxis of neural tube defects with folic acid in pregnant women from a health district]

OBJECTIVES

To evaluate the knowledge about the prophylaxis of neural tube defects (NTD) with supplements of folic acid and the correct therapeutic compliance.

DESIGN

Observational, descriptive study.

PARTICIPANTS

346 pregnant women attending to deliver at the department of obstetrics and gynaecology, university hospital.

MATERIAL AND METHODS

The following outcomes were gathered through a questionnaire: demographic variables, previous personal or family history of a pregnancy affected by a NTD, planning of pregnancy, knowledge about the value of the use of folic acid, health professional who prescribed it, and the beginning and duration of the prophylaxis.

RESULTS

95% of the participants used supplements of folic acid during their pregnancy. A 34% was able to describe folic acid as an efficacious method to diminish the incidence of NTD. The percentage of women who used correctly the prophylaxis was significantly greater when it was prescribed by a family physician (P=.003).

CONCLUSIONS

A great proportion of women from our health district take folic acid during pregnancy, but just a small percent accomplishes the treatment correctly. The lack of awareness among women about the need for periconceptional folic acid supplements and how it should be taken following the recommendations to prevent NTD are the main reasons for not accomplishing a correct prophylaxis. Family physicians could play an important role as health educators.

Water chlorination and birth defects: a systematic review and meta-analysis

The authors used the Medline data retrieval system for 1966-2001 to identify and synthesize the epidemiological evidence for adverse effects of prenatal exposure to chlorination byproducts on birth defects. For 5 studies that provided estimates of the effect of exposure on 1 or several birth defects, the authors calculated summary odds ratios and 95% confidence intervals using the Mantel-Haenszel method for a fixed-effects model, and the DerSimonian-Laird method for a random-effects model. The results of this meta-analysis provide evidence for an effect of exposure to chlorination byproducts on the risk of any birth defect, and of neural tube and urinary system defects. The results for respiratory system, major cardiac, and oral cleft defects were heterogeneous and inconclusive. Differences in the susceptibility of populations, and different approaches in exposure assessment, may explain the heterogeneity of the results.

The prevention of congenital anomalies with periconceptional folic acid supplementation

Large randomized trials have demonstrated the critical role of folic acid supplementation in the prevention of neural tube defects. Since 1992, a number of national and international professional societies have released guidelines recommending folic acid supplementation of at least 0.4 mg/day for all women of childbearing age or women planning pregnancies, and 4 mg/day for women with a previous infant with a neural tube defect. Furthermore, a reduction in the incidence of congenital cardiac and urologic anomalies has been demonstrated in some studies following periconceptional folic acid supplementation. There is growing evidence of a possible role of folic acid supplementation in the prevention of other congenital anomalies, including cardiac defects. Since 1998, mandatory fortification of certain foods with folate has been associated with at least a 54% reduction in the incidence of open neural tube defects, yet rates of periconceptional folic acid use remain suboptimal, especially in minority women. Innovative strategies in educating women, health-care providers, and pharmacists on the benefits of folic acid supplementation need to be explored. Mandatory folate fortification of foods needs to be defined and monitored.

Folic acid supplements during early pregnancy and likelihood of multiple births: a population-based cohort study

BACKGROUND

Folic acid supplements are recommended for women of childbearing age to prevent neural tube defects in their offspring. Results of some studies, however, suggest an increase in multiple births associated with use of vitamin supplements that contain folic acid during pregnancy. Our aim was to assess this association.

METHODS

We used data from a population-based cohort study from which we assessed the occurrence of multiple births in women (n=242015) who had participated in a campaign to prevent neural tube defects with folic acid supplements (400 microg per day) in China. Folic acid use was ascertained before pregnancy outcome was known. We studied the relation between multiple births and any use of folic acid pills before or during early pregnancy; additionally, we investigated mechanisms by which folic acid could potentially affect the occurrence of multiple births by examining pill-taking at three time periods: before ovulation, around the time of fertilisation, and after conception.

FINDINGS

1496 (0.62%) multiple births occurred in a cohort of 242015 women who had registered with the study between October, 1993, and September, 1995, and who had a pregnancy not affected by a birth defect; the rate of multiple births in women who did and did not take folic acid before or during early pregnancy was 0.59% and 0.65%, respectively (rate ratio 0.91; 95% CI 0.82-1.00).

INTERPRETATION

Our findings suggest that consumption of folic acid supplements during pregnancy is not associated with an increased occurrence of multiple births.

Epilepsy and pregnancy: Report of an Epilepsy Research Foundation Workshop

Pregnancy in women with epilepsy (WWE) is known to be associated with a higher risk of congenital malformations than is associated with pregnancy in non-epileptic women. Several factors have been identified to account for the increased risk, including the direct teratogenic effects of antiepileptic drug (AED) therapy, indirect effects of these drugs by interfering with folate metabolism, genetic abnormalities in drug or folate metabolism, and possibly an arrhythmogenic effect of maternal drug therapy on the embryonic heart, leading to ischaemia in developing tissues. A harmful effect of maternal seizures on the developing embryo has not been proven, although seizures and status epilepticus account for most of the excess maternal mortality in women with epilepsy. Abrupt withdrawal of drug therapy by the mother may be an important contributory factor. Less is known about the psychomotor development of children born to mothers with epilepsy because few studies have been designed to follow their progress throughout childhood. Retrospective studies suggest that impaired cognitive development may be associated with maternal drug therapy, particularly valproate. There is an urgent need to evaluate these risks and, with this in mind, several prospective registers have been set up to collect data from pregnancies in women with epilepsy.

Neural tube defects in the offspring of thalassemia carriers

OBJECTIVES

The risk of neural tube defects (NTDs) is negatively correlated with maternal folate levels in early pregnancy. Thalassemia carriers often have reduced red cell folate contents. The aim of this study was to verify whether thalassemia carriers are at increased risk of having offspring with a NTD.

METHODS

We retrospectively evaluated the prevalence of thalassemia carriers among 75 women who had prenatal diagnoses of NTDs made at our center.

RESULTS

The prevalence of beta-thalassemia carriers among the affected pregnancies was significantly higher than in the general population (22.5 versus 14%, p < 0.05, chi(2) test).

CONCLUSION

Although inconclusive, these data indicate that folate supplementation is mandatory among women with thalassemia who are planning a pregnancy.

Influence of reporting error on the relation between blood folate concentrations and reported folic acid-containing dietary supplement use among reproductive-aged women in the United States

BACKGROUND

Folic acid intake is the most important predictor of blood folate concentrations among nonpregnant women, but the reporting of folic acid-containing supplement use is subject to error.

OBJECTIVE

We assessed the effect of reporting error of supplement use on blood folate concentrations.

DESIGN

Data from the third National Health and Nutrition Examination Survey were analyzed. Respondents to that survey were asked twice about supplement use: ie, during the household interview, to recall use in the previous month, and during the physical examination, to recall use in the previous 24 h. To examine the effect of error reporting, we classified women (aged 15-44 y) into 5 groups according to supplement use in the previous month (nonusers, those ingesting < 400 micro g/d, and those ingesting >or= 400 micro g/d) and in the 24 h before the physical examination (yes or no). We expected nonappreciable differences in red blood cell (RBC) folate concentration by status of 24-h recall within the same category of previous-month use because RBC folate reflects long-term average consumption. We calculated covariate-adjusted means of serum and RBC folate concentrations.

RESULTS

Among women who reported average daily use of >or= 400 micro g folic acid in the previous month, the adjusted mean RBC folate was 436.5 nmol/L (95% CI: 406.7, 466.3 nmol/L) in those who did not take the supplement in the previous 24 h and 519.7 nmol/L (95% CI: 496.2, 543.2 nmol/L) in those who did do so (P < 0.01). This significant difference indicates apparently erroneous reporting of supplement use in the previous month by some participants.

CONCLUSION

The effect of reporting error on blood folate concentrations is important in interpreting survey results, evaluating health education campaigns, and identifying populations needing special education programs.

Audit of prenatal and postnatal diagnosis of isolated open spina bifida in three university hospitals in The Netherlands

OBJECTIVE

To audit the current Dutch policy of prenatal detection of isolated open spina bifida based on offering detailed ultrasound examination only on indication.

METHODS

A retrospective analysis of prenatally diagnosed isolated spina bifida cases and of newborns diagnosed with this condition was carried out in three university hospitals. The data were collected from databases and clinical records of the departments of prenatal diagnosis, obstetrics, neonatology, child neurology and neurosurgery of the three centers.

RESULTS

Between January 1996 and December 1999, 88 cases of isolated open spina bifida were diagnosed prenatally by ultrasound investigation. Thirty-eight cases (43%) were diagnosed before the 24th week of gestation. Of these, 35 (92%) ended in termination of the pregnancy at the parents' request. Of the remaining 50 cases (57%) diagnosed after the 24th week of gestation, eight (16%) pregnancies were terminated beyond the legal limit for termination due to the severity of the condition. Of the 88 cases of isolated spina bifida, 25 infants (28%) were still alive at the age of 4 years. In the same audit period 112 newborn infants with isolated open spina bifida were admitted to the neonatology, child neurology, or neurosurgery ward of the three centers. Of these cases, 47 (42%) had been diagnosed prenatally and 65 (58%) were an unexpected finding at birth. In 24 infants (21%) surgical treatment was withheld because of the severity of the condition and predicted poor outcome, whereas the remaining 88 infants (79%) underwent surgical repair.

CONCLUSION

The current practice in The Netherlands of offering ultrasound screening to high-risk patients only leads to the early detection of a minority of cases of spina bifida. Most cases are diagnosed either after the 24th week of gestation or they remain undiagnosed until after birth. When spina bifida is diagnosed before the 24th week of gestation the vast majority of parents opt for termination. In order to reduce the birth prevalence of spina bifida in The Netherlands the introduction of a policy of routine ultrasound screening should be considered.

Folate content in strawberries (Fragaria x ananassa): effects of cultivar, ripeness, year of harvest, storage, and commercial processing

Folate concentrations in strawberries and folate retention during storage and commercial processing of strawberries were investigated. No previous study has focused on the effects of cultivar, ripeness, and year of harvest of strawberries with respect to the folate content. This study showed the folate concentration in strawberries to significantly depend on all of these different factors. Total folate was quantified using a modified and validated radioprotein-binding assay with external calibration (5-CH(3)-H(4)folate). Folate content in 13 different strawberry cultivars varied from 335 microg/100 g of dry matter (DM) for cv. Senga Sengana to 644 microg/100 g of DM for cv. Elsanta. Swedish harvests from 1999 and 2001 yielded higher folate concentrations than did the harvest from 2000, and the grade of ripeness affected the folate content in strawberries. This study indicated high folate retention in intact berries during storage until 3 or 9 days at 4 degrees C (71-99%) and also in most tested commercial products (79-103%). On the basis of these data fresh strawberries as well as processed strawberry products are recommended to be good folate sources. For instance, 250 g (fresh weight) of strawberries ( approximately 125 microg of folate) supplies approximately 50% of the recommended daily folate intake in various European countries (200-300 microg/day) or 30% of the U.S. recommendation (400 microg/day).

Association of neural tube defects and folic acid food fortification in Canada

Many women do not receive folic acid supplements before conception. In response, most of Canada's cereal grain products were being fortified with folic acid by January, 1998, thereby providing an additional 0.1-0.2 mg per day of dietary folate to the Canadian population. We assessed the effect of supplementation on prevalence of open neural tube defects in the province of Ontario. Among 336 963 women who underwent maternal serum screening over 77 months, the prevalence of open neural tube defects declined from 1.13 per 1000 pregnancies before fortification to 0.58 per 1000 pregnancies thereafter (prevalence ratio 0.52, 95% CI 0.40-0.67, p<0.0001). At a population level, folic acid food fortification is associated with a pronounced reduction in open neural tube defects.