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PubMed2005

Reduction of birth prevalence rates of neural tube defects after folic acid fortification in Chile.

To verify whether the decreasing neural tube defects birth prevalence rates in Chile are due to folic acid fortification or to pre-existing decreasing trends, we performed a population survey using a network of Estudio Colaborativo Latino Americano de Malformaciones Congenitas (ECLAMC, Latin American Collaborative Study of Congenital Malformations) maternity hospitals in Chile, between the years 1982 and 2002. Within each maternity hospital, birth prevalence rates of spina bifida and anencephaly were calculated from two pre-fortification periods (1982-1989 and 1990-2000), and from one fortified period (2001-2002). There was no historical trend for spina bifida birth prevalence rates before folic acid fortification, and there was a 51% (minimum 27%, maximum 66%) decrease in the birth prevalence rates of this anomaly in the fortified period. The relative risks of spina bifida were homogeneous among hospitals in the two period comparisons. There was no historical trend for the birth prevalence of anencephaly comparing the two pre-fortified periods, but the relative risks were heterogeneous among hospitals in this comparison. There was a 42% (minimum 10%, maximum 63%) decrease in the birth prevalence rate of anencephaly in the fortified period as compared with the immediately pre-fortified period, with homogeneous relative risks among hospitals. Within the methodological constraints of this study we conclude that the birth prevalence rates for both spina bifida and anencephaly decreased as a result of folic acid fortification, without interference of decreasing secular trends.

Anencephaly↗
PubMed1996

[Prevalence, clinical aspects and prognosis of neural tube defects in The Netherlands].

OBJECTIVE: To determine the live birth prevalence of neural tube defects (NTD) in the Netherlands and describe the clinical picture. DESIGN: Descriptive. SETTING: TNO Prevention and Health, Leiden, the Netherlands. METHOD: Data collected through active surveillance of NTD on a monthly basis by paediatricians throughout the country. RESULTS: From October 1993 to September 1995, 203 infants with NTD were registered. Six were diagnosed with anencephaly, 10 with encephalocele and 157 with spina bifida. On 30 children no further information was available. Seventy-nine per cent of children with spina bifida had a myelomeningocele and 11% had a meningocele. Hydrocephalus was found in 75% of all registered infants and in 81% of infants with myelomeningocele. In 18% of the latter group a kyphosis was diagnosed. In 45% of 131 children prognosis of ambulation fair: they were expected to learn to walk. In 32% prognosis for motor disorder was very poor, and unsupported sitting was considered to be unlikely. At the time of registration, when most children were less than a month old, 55 (27%) had died; in infants with a myelomeningocele this was 35%. In many children treatment had not been started, probably because the prognosis was poor. Some had not been referred to a multidisciplinary team and only one of them received a hydrocephalus valve. CONCLUSION: The prevalence of spina bifida in the Netherlands is at least 100 live-born children per year among 195,000 total births. Mortality in the first month is high and for many surviving infants a severe handicap can be expected. Preventive strategies (such as folic acid supplementation) are urgently needed.

Activities of Daily Living↗
PubMed2003

Vitamin B12 insufficiency and the risk of fetal neural tube defects.

BACKGROUND: Although maternal folate insufficiency is a risk factor for fetal neural tube defects (NTDs), there is controversy about whether vitamin B12 (B12) insufficiency is also associated with an increased risk of NTDs. AIM: To investigate whether low maternal B12 is associated with an increased risk of fetal NTDs. DESIGN: Systematic review. METHODS: A systematic search of Medline between 1980 and October 2002, with an examination of the citations of all retrieved studies. Studies were included that: (i) used a cohort or case-control design; (ii) included case mothers with a prior or current NTD-affected pregnancy; (iii) assessed a group of unaffected 'controls'; and (iv) measured the vitamin B12 status of all participants. RESULTS: Overall, 17 case-control studies were included, mean sample size 33 cases and 93 controls. In 5/6, mean amniotic fluid B12 concentration was significantly lower in case mothers than in controls. Of 11 that measured maternal serum or plasma B12, three observed a significantly lower mean concentration in case mothers vs. controls, while five others found a non-significant lower trend in the case group. One study observed a significantly higher mean concentration of maternal serum methylmalonic acid among the maternal cases, while another found a non-significant lower mean concentration of plasma holo-transcobalamin. Five studies estimated the risk of NTDs in relation to low B12 or B12-related metabolic markers: it was significantly increased in three studies, with a non-significant trend in the fourth. DISCUSSION: There seems to be a moderate association between low maternal B12 status and the risk of fetal NTDs. However, several design limitations, and the inclusion of few study participants, may have under-represented this. A large observational study, using reliable and valid indicators of B12 status in early pregnancy, could best assess the association between B12 insufficiency and the risk of fetal NTDs.

Case-Control Studies↗
PubMed1985

Can we afford screening for neural tube defects? The South Wales experience.

Clinical and financial gains and losses accruing from five different options for screening for open neural tube defects were estimated, based principally on the results of detailed monitoring of inputs and outcomes and of process costs in the South Wales Anencephaly and Spina Bifida Study. As well as estimating the overall clinical costs of a screening service it was shown that if the prevalence, including terminations, of open neural tube defects is between 1.25 and five per 1000 births the financial cost of avoiding the birth of a seriously handicapped child who would survive for more than 24 hours is in the range 9000 pounds- 54000 pounds depending on the option adopted and the prevalence of the condition in the target population. Prevalence is the biggest determinant of cost. The data should provide a basis for assessment and discussion of resource priorities in the National Health Service.

Anencephaly↗
PubMed1998

Absorption of dietary and supplemental folate in women with prior pregnancies with neural tube defects and controls.

BACKGROUND: The Public Health Service of the United States recommends that all women capable of childbearing consume .4 mg (400 microg) folic acid per day to decrease the risk of having a pregnancy affected by a neural tube defect such as spina bifida or anencephaly. Three strategies are available to women to achieve this goal: use of dietary supplements; use of fortified foods; and/or increased intake of naturally occurring folate from foods. Identification of the most effective vehicle for delivery of folate to all women is critical in order to prevent these devastating congenital defects. OBJECTIVE: To investigate the difference in response to an oral load of folate both from naturally occurring food sources and synthetic supplements among women with prior pregnancies affected by neural tube defects and controls. METHODS: We compared the absorption of test doses of 400 microg pteroylglutamic acid (unconjugated or synthetic folic acid found in supplements) and 400 microg pteroylpolyglutamic acid (conjugated or food folate) in 10 women with a history of neural tube defect affected pregnancies and eight controls with normal birth outcomes. The folate test dose was given as either 32 fluid ounces of orange juice or a folic acid single supplement pill. All participants received each test dose at separate clinic visits. The response to each test dose was measured by constructing an area under the curve (AUC) from the serum folate levels at 1, 2 and 3 hours post dose and applying a t-test to compare within and between cases and controls. We also compared red cell folate, vitamin B12, zinc and homocysteine between cases and controls. RESULTS: Within group comparisons showed that the area under the curve was significantly greater for the pteroylglutamic acid dose compared to the pteroylpolyglutamic acid dose for both cases and controls (p=0.02 and p=0.03, respectively). In a between group comparison, control women had a greater serum folate response to both forms of the vitamin compared to the case women, but the difference reached statistical significance only for the pteroylglutamic acid dose (p=0.02). Other measured nutrients differed between cases and controls, but did not reach statistical significance. CONCLUSION: We conclude that for all women synthetic folic acid as supplements or fortified foods may be the best way to increase acute folate levels in the blood, and thus delivery to the developing embryo. Further, since case women had a diminished response to both forms of the vitamin, and some case women had almost no response, we speculate that women with prior affected pregnancies may need a larger dose of folate to elicit a plasma response equivalent to the general population.

Absorption↗
PubMed1995

[Prevention of neural tube defects by folic acid administration in early pregnancy. Joint recommendations of the German Society of Nutrition, Gynecology and Obstetrics, Human Genetics, Pediatrics. Society of Neuropediatrics].

OBJECTIVE: Is folic acid supplementation for the prevention of neural tube defects effective? How could periconceptional folic acid supplementation be recommended in Germany and actually put into practice? METHODS: Analysis of the available literature and of the German health care system. RESULTS: According to the available data, it is likely that the rate of neural tube defects can be reduced by periconceptional folic acid. Matters of concern regarding its practical implementation are: difficulties regarding the information of the target group; the presently rare ingestion of vitamin supplements by women of child-bearing age in Germany; the lack of suitable folic acid preparations. CONCLUSIONS: Several German societies have recommended folic acid supplements for women who plan to become pregnant: 4 mg for those at high risk (previous child with neural tube defect) and 0.4 mg/daily for women without a particular risk.

Dose-Response Relationship, Drug↗
PubMed2005

[Does folic acid have effects on other health problems than neural tube defects?].

BACKGROUND: While it is widely accepted that periconceptional supplement of 400 microg (microgram) folic acid reduces the risk of neural tube defects in pregnancy, it remains to be established whether folic acid has other beneficial effects on larger population groups. Evidence concerning effect of increased intake on cardiovascular disease, cancer and other diseases has recently been evaluated in a report to the Directorate of Health and Social Welfare in Norway. MATERIAL AND METHODS: Research reports published mainly from 1998 to 2003 on folic acid intake and disease have been evaluated. RESULTS: Sufficient evidence that increased folic acid intake may prevent cancer or cardiovascular diseases is not yet available, hence at present there is no indication for recommending augmented intake for other groups than fertile women. However, several intervention studies with folic acid supplementation are in progress to establish its effect on cardiovascular mortality and morbidity. INTERPRETATION: If the ongoing intervention studies show a beneficial clinical effect on cardiovascular disease, it would be a further argument for fortification of foods, in addition to reducing the risk of neural tube defects in pregnancy.

Cardiovascular Diseases↗
PubMed1981

Prenatal diagnosis of neural tube defects: predictive value of AF-AFP in a low-risk population.

Amniotic fluid alpha-fetoprotein (AF-AFP) determinations were performed on 1,215 women who were at low risk for fetal neural tube defects and who were undergoing mid-trimester amniocentesis for cytogenetic indications, primarily age-related aneuploidy. Maternal sera obtained before amniocentesis and amniotic fluids were assayed in duplicate for alpha-fetoprotein by radioimmunoassay. Of the 1,215 low-risk women, eight (0.7%) had significant elevations of AF-AFP (greater than or equal to +5 SD). In none of the cases was the elevation associated with a fetal neural tube defect. Two cases with elevated AF-AFP were associated with chromosome aberrations; one with impending fetal demise; one with fetal blood contamination; and one case was due to a laboratory error. In one case, no source for the elevated AFP was found, and a normal infant was delivered at term. In the final two cases, the cause of the elevated AF-AFP was a fetal abdominal wall defect (one gastroschisis and one omphalocele). The predictive value of an elevated AFP varies with the population screened, and is reduced by routine ultrasonography before amniocentesis, which at least identifies anencephaly. In a low-risk population, an elevated AF-AFP is most often not associated with a fetal neural tube defect. Because of the low predictive value and the nonspecificity of AF-AFP, genetic counselors should reconsider the recommendation of routine AF-AFP in low-risk maternal populations.

Amniocentesis↗
PubMed1982

An epidemiologic study of neural tube defects in Los Angeles County I. Prevalence at birth based on multiple sources of case ascertainment.

Epidemiologic studies of the neural tube defects (NTDs), anencephalus and spina bifida, have for the most part been based on single sources of case ascertainment in past studies. The present investigation attempts total ascertainment of NTD cases in the newborn population of Los Angeles County residents for the period 1966-1972. Design of the study, sources of data, and estimates of prevalence rates based on single and multiple sources of case ascertainment are here discussed. Anencephalus cases totaled 448, spina bifida 442, and encephalocele 72, giving prevalence rates of 0.52, 0.51, and 0.08 per 1000 total births, respectively, for these neural tube defects--rates considered to be low. The Los Angeles County prevalence rates are compared with those of other recent North American studies and support is provided for earlier suggestions of low rates on the West Coast.

Anencephaly↗
PubMed2006

Neural tube defects and associated anomalies in a fetal and perinatal autopsy series.

Neural tube defects (NTDs) are congenital malformations of the central nervous system (CNS) secondary to abnormal closure of the neural tube during embryonic development. This study provides information on NTD rate, distribution, associated morphologic anomalies and organ weights in a Danish fetal and perinatal autopsy series during a 16 year period. The data were extracted from the autopsy reports of a consecutive series of 1984 fetal and perinatal autopsies from the Copenhagen area performed in the period 1989-2004. Registered parameters included: The location and morphology of the NTD, associated morphological anomalies, and organ weights. Organ weights were evaluated according to new fetal autopsy standards and grouped as low, normal or high. Ninety-seven NTD cases were found (4.9%): Spina bifida (38 cases), cephalocele (17 cases) and anencephaly (42 cases). 63% of NTD cases had associated morphologic anomalies. Among the most common were hydrocephalus, NTD in another region, and anomalies in the urogenital system. 58% of the NTD cases had abnormal weight of one or more organs. Most notable was low adrenal weight not only in anencephalic fetuses but also in cases with cephalocele, suggesting a possible association.

Anencephaly↗
PubMed1983

The efficacy of a serum screening service for neural-tube defects: the South Wales experience.

Serum-alpha-fetoprotein (AFP) levels were measured in more than 15 000 pregnant women in an investigation designed to examine the operational issues entailed in a large-scale population screening programme for antenatal detection of neural-tube defects. The proportion of open neural-tube defects (ONTD) terminated as a result of serum screening was 56.1% (66.6% for anencephaly and 40.7% for open spina bifida). The principle causes of poor efficacy were: failure of pregnant women to undergo screening (18.2% of ONTD were not screened); failure of the screening test to detect ONTD (20.4% of those screened were below the 90th centile); decisions against termination of detected ONTD (14% of ONTD detected by serum AFP were not terminated). Given present practices and knowledge it is doubtful whether overall efficacy levels above 65% for open spina bifida can be achieved under normal service conditions. The establishment of a regional or national screening programme on grounds of clinical efficacy alone may be premature. The decision would seem to hinge principally around a careful consideration of the economic issues.

Anencephaly↗
PubMed2000

Second trimester levels of maternal serum inhibin A in pregnancies affected by fetal neural tube defects.

Inhibin A is effective as a second trimester maternal serum marker for Down syndrome screening. In the present study, inhibin A levels were measured in second trimester maternal serum samples from 28 pregnancies affected with open neural tube defects; 12 associated with open spina bifida and 16 associated with anencephaly. Each measurement was expressed as a multiple of the median (MoM) for control singleton pregnancies (n=1464) of the same completed week of gestation. Inhibin A levels were not significantly altered in cases of open neural tube defects; the median value was 0.96 MoM in cases of open spina bifida and 1.19 MoM in cases of anencephaly. Therefore, second trimester maternal serum inhibin A levels will not have an impact on prenatal detection of open neural tube defects.

Anencephaly↗
PubMed1991

Heterogeneity of neural tube defects in Europe: the significance of site of defect and presence of other major anomalies in relation to geographic differences in prevalence.

In the period 1980-1987, neural tube defects were two to three times more prevalent in populations covered by EUROCAT registries in the United Kingdom and Ireland (UKI) than in Continental Europe and Malta (CEM). 1864 NTD cases in a total population of 580,000 births in UKI and 455 cases in a population of 380,000 births in CEM were analysed to find if there were differences in the ratio of prevalence rates between UKI and CEM according to site of the defect and association with non-central nervous system (CNS) anomalies. The prevalence rate ratio was high for anencephaly with accompanying spina bifida, iniencephaly, and upper spina bifida, and low for encephalocele, lower spina bifida, and anencephaly without other neural tube defects. There was a greater female excess for anencephaly with accompanying spina bifida, iniencephaly, and upper spina bifida than for other defects in both geographic areas. There was a female excess for encephalocele in UKI but a male excess in CEM. Certain sites (anencephaly with accompanying spina bifida, iniencephaly, and encephalocele) were more likely to have accompanying non-CNS anomalies. The prevalence rate ratio of multiply malformed NTD was in general lower than for isolated NTD but showed the same pattern by site. The prevalence rate ratio was high for multiply malformed anencephaly with accompanying spina bifida, iniencephaly, and upper spina bifida. The sex ratio was similar between isolated and multiply malformed cases when site of the defect is taken into account. It is concluded that the geographic prevalence pattern and sex ratio differ according to site of NTD but do not differ substantially according to whether NTD is isolated or associated with non-CNS anomalies.

Abnormalities, Multiple↗
PubMed2001

Association between lower hair zinc levels and neural tube defects.

Though folic acid supplementation has reduced the incidence of Neural Tube Defects (NTD), NTD still constitutes one of the important congenital malformations having wide medical, social and ethical implications. Zinc deficiency has been reported to produce NTD in animals. This study was designed to evaluate zinc status of the newborn babies with NTD and their mothers. Eighty newborn babies with NTD and their mothers served as cases. Eighty apparently normal newborn babies and their mothers served as controls. Serum and scalp hair zinc levels were analyzed by atomic absorption spectrophotometry. The mean (+/- SD) serum and hair levels in normal mothers were 74.1 +/- 4.1 micrograms/dl and 142.3 +/- 8.0 micrograms/g respectively. The mean (+/- SD) serum and hair levels of the mothers who delivered NTD babies were 75.7 +/- 5.6 micrograms/dl and 129.9 +/- 5.3 micrograms/g respectively. The mean (+/- SD) serum and hair levels in normal newborn babies were 77.8 +/- 5.3 micrograms/dl and 188.8 +/- 6.2 micrograms/g respectively. The mean (+/- SD) serum and hair levels in NTD babies were 80.1 +/- 12.9 micrograms/dl and 174.2 +/- 10.7 micrograms/g respectively. The hair zinc levels of the affected babies and their mothers were significantly lower (P < 0.001) than the controls. This study has found association between NTD and decreased hair zinc levels and large population based studies are recommended to confirm the association between zinc and NTD and to investigate whether zinc supplementation would reduce the overall incidence of NTD.

Developing Countries↗
PubMed1978

Inidcations for prenatal diagnosis in relatives of patients with neural tube defects.

We have reviewed the family histories of children with neural tube defects to determine which relatives are at sufficient risk to be offered amniocentesis for prenatal diagnosis. The recurrence risks for sibs was 6%; therefore, women with one affected child should be made aware of the availability of this test for monitoring subsequent pregnancies. The empiric recurrence risks for various groups of second and third degree relative exceeds 1% only for mothers' sisters' children. The lower values for the other groups may reflect either true biologic differences of reporting biases. Unit the matter is clarified, all sibs of affected children and all sibs of the parents of affected children should be informed of the availability of amniocentesis for monitoring their (or their spouse's) pregnancies.

Amniocentesis↗
PubMed1981

Improved diagnosis of neural tube defects: measurement of concanavalin A-reactive variants of AFP in amniotic fluid.

The proportion of alphafetoprotein (AFP) not reacting with Concanavalin A(Con A) was determined by crossed line affinity immunoelectrophoresis (CLAIE) in amniotic fluid obtained from 16 pregnancies with open neural tube defects and other fetal abnormalities, and 25 pregnancies with normal outcome. The percentage of Con A non-reactive AFP was significantly lower in the presence of open neural tube defects (less than 3.9%, n = 13) compared with that in normal pregnancy (range 6.4-25.2%, n = 25). In this retrospective analysis, 2 pregnancies affected by open neural tube defect escaped diagnosis on the basis of an ambiguous total AFP estimation (+2SD less than x less than +5SD) in the amniotic fluid. These observations suggest that the elimination of false diagnose based on total AFP levels may be possible, if supplementary analysis by CLAIE is performed.

Amniotic Fluid↗
PubMed1975

[Present situation of prenatal diagnosis of neural tube defects].

Anencephaly and spina bifida both are malformations of unknown etiology which are caused by an absent or incomplete closure of the neural tube. The risk of recurrence for the malformations is 5% in families with one child with a neural tube defect and 10%, if two such children have already been born. Neural tube defects can be diagnosed already before 20th week of gestation by ultrasonics and alpha-fetoprotein measurement in amniotic fluid, if an underdeveloped neurocranium or a free communication between amniotic and cerebrospinal fluid is present. By these diagnostic techniques and possibly following interruption the probability in risk families can be significantly lowered.

Abortion, Legal↗
PubMed1997

Congenital abnormalities in Durgapur Steel Plant Hospital with special reference to neural tube defect.

In a retrospective study of congenital abnormalities from January, 1991 to December, 1993 in Durgapur Steel Plant Hospital, a referral hospital covering wide industrial belt, the incidence of neural tube defects was detected remarkably high. It was revealed that increased incidence of neural tube defects was found in patients from low socio-economic status with gross nutritional deficiency and inadequate antenatal care.

Congenital Abnormalities↗