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PubMed2006

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.

Adult↗
PubMed2006

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.

Animals↗
PubMed1988

Neutral-red uptake and expression of monocytic antigens in amniotic-fluid mononuclear phagocytes: evaluation of a novel approach for prenatal diagnosis of neural-tube defects.

In cases of fetal neural-tube defects macrophages are present in the amniotic fluid. We found that these viable phagocytic cells take up neutral-red and are easily identified as "red cells" by microscopic examination. This method is suitable for the rapid identification and counting of amniotic-fluid macrophages in suspension. We have studied 298 amniotic fluid samples. In the 226 normal cases studied, 0 to 1,200 macrophages per milliliter amniotic fluid have been found. In contrast, we found 1,250 to 99,000 macrophages per milliliter amniotic fluid in our 70 open neural tube defect (ONTD) cases. Statistical evaluation was performed to estimate the normal and pathologic ranges. Specificity and sensitivity of the neutral-red test and predictive value of positive and negative results have been calculated and presented in comparison with alpha-fetoprotein (AFP) determinations and ultrasonic methods. In 5 cases of anencephaly and 7 normal cases amniotic fluid cells were studied by immunocytochemistry: mononuclear cells present in the abnormal cases showed intense immunoreactivity for the Mo1 and Mo2 surface antigens of the phagocytic cell lineage.

Amniotic Fluid↗
PubMed2006

Recurrent neural tube defects.

We report a case of recurrent neural tube defects in a 30-year-old multigravida with no medical or family history of note. She presented with a significant history of having three (out of four) previous pregnancies affected by neural tube defects diagnosed at the 20-week foetal anomaly ultrasonographical scans, and which resulted in mid-trimester pregnancy terminations. Previous investigations for the foetuses did not yield any obvious cause. We discuss the possible differential diagnoses and aetiological factors. Rare causes of neural tube defects need to be excluded in recurrent cases with no obvious aetiology.

Adult↗
PubMed1992

Folate deficiency alone does not produce neural tube defects in mice.

The incidence of neural tube defects was studied in mouse embryos from dams fed an amino acid-based diet containing 45, 91, 136, 181, 227 or 453 nmol folic acid/kg diet (Experiment 1) or 227, 453, 566, 680, 906, 1132, 1698 or 2266 nmol folic acid/kg diet (Experiment 2). Reproductive tracts were examined 12 d postcoitum and gross and microscopic examination of all embryos was performed. A single implantation was found at levels less than or equal to 181 nmol folic acid/kg diet. With one exception, bred mice fed 227 or 453 nmol folic acid/kg diet in Experiment 1 had 100% resorptions. In Experiment 2, 100% of implantations in mice fed 227 nmol folic acid/kg diet and approximately 75% of implantations in mice fed 453 or 566 nmol folic acid/kg diet resorbed. The 906 nmol folic acid/kg diet was sufficient for successful pregnancy. Mice fed 227 nmol folic acid/kg diet in Experiment 2 weighed approximately 80% of mice fed higher levels of folic acid. Inadequate dietary folic acid resulted in fewer and smaller embryos (which developed normally). These results suggest that folate deficiency alone is insufficient to produce neural tube defects in Swiss-Webster mice. Because individual micronutrients (e.g., folate) can be omitted from the amino acid-based diet, the specific role of folic acid in neurulation can now be studied systematically.

Animals↗
PubMed1995

Homocysteine metabolism in pregnancies complicated by neural-tube defects.

Folic acid taken around the time of conception can prevent many neural-tube defects. Women with low-normal vitamin B12 values may also be at increased risk. We considered whether homocysteine metabolism via the enzyme methionine synthase, which requires both folate and B12, could be the critical defect in folate-related neural tube defects. Blood was obtained during pregnancies that produced 81 infants with neural-tube defects and 323 normal children. Samples were assayed for homocysteine, methylmalonic acid, plasma folate, red-cell folate, and B12. Mothers of children with neural-tube defects had significantly higher homocysteine values (8.62 [SD 2.8] mumol/L) than did B12-matched controls (7.96 [2.5] mumol/L, p = 0.03). The difference was significant (p = 0.004) in the lower half of the B12 distribution after adjusting for plasma folate. Our study shows that an abnormality in homocysteine metabolism, apparently related to methionine synthase, is present in many women who give birth to children with neural-tube defects. Overcoming this abnormality is likely to be the mechanism by which folic acid prevents neural-tube defects. These findings suggest that the most effective periconceptional prophylaxis to prevent neural-tube defects may require B12 as well as folic acid.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1992

The changing epidemiology of neural tube defects. United States, 1968-1989.

OBJECTIVE: To describe the recent trends and epidemiologic characteristics of neural tube defects in the United States. RESEARCH DESIGN: Ongoing surveillance data. SETTING: Two birth defect surveillance systems: the nationwide Birth Defects Monitoring Program and the Metropolitan Atlanta (Ga) Congenital Defects Program for 1970 through 1989 and 1968 through 1989, respectively. PARTICIPANTS: Between 1970 and 1989, using discharge diagnoses of approximately 1 million live-born and stillborn infants per year, the Birth Defects Monitoring Program identified 15,503 cases of spina bifida and anencephaly. Between 1968 and 1989, using discharge diagnoses and clinical records until age 1 year of 38,000 infants per year, the Metropolitan Atlanta Congenital Defects Program identified 800 cases of spina bifida and anencephaly. INTERVENTIONS: None. MEASUREMENTS/MAIN RESULTS: Nationwide, neural tube defect rates have declined from 1.3 per 1000 births in 1970 to 0.6 per 1000 births in 1989. In Atlanta, neural tube defect rates have declined from 2.0 per 1000 births in 1968 to 0.6 per 1000 births in 1989. Several changes in the epidemiologic characteristics of neural tube defects were observed: (1) the proportion of spina bifida cases has increased; (2) the proportion of neural tube defect cases compared with the proportion of other unrelated defects has increased; (3) the race ratio of whites to other races for isolated neural tube defect cases has declined in Atlanta; and (4) the rate of isolated neural tube defects in females has also decreased. CONCLUSIONS: The declining rates of neural tube defects can be partially explained by increased widespread prenatal diagnostic techniques, strongly suggesting the role of environmental factors in neural tube defects. In particular, the use of multivitamins and folic acid to prevent the occurrence of neural tube defects needs further evaluation. Nevertheless, the changing clinical and epidemiologic characteristics of cases over time points to the etiologic heterogeneity of these conditions.

Anencephaly↗
PubMed1996

[A study on risk factors of neural tube defects].

One hundred and twenty-three cases with neural tube defects collected during 1991 to 1993 from 12 hospitals with birth defect surveillance in Hebei Province, and their pair-matched controls were analyzed with single and multiple conditional logistic regression to study the effects of food and drinking water on occurrence of neural tube defects. Results showed factors contributing to neural tube defects were maternal previous history of birth defects, much consumption of dried and pickled vegetables during pregnancy, too much nitrate content in drinking water (containing more than 10 mg nitrogen per liter of water), less consumption of meat, eggs, and beans in their diet.

China↗
PubMed1996

Neural tube defects and abnormal brain development in F52-deficient mice.

F52 is a myristoylated, alanine-rich substrate for protein kinase C. We have generated F52-deficient mice by the gene targeting technique. These mutant mice manifest severe neural tube defects that are not associated with other complex malformations, a phenotype reminiscent of common human neural tube defects. The neural tube defects observed include both exencephaly and spina bifida, and the phenotype exhibits partial penetrance with about 60% of homozygous embryos developing neural tube defects. Exencephaly is the prominent type of defect and leads to high prenatal lethality. Neural tube defects are observed in a smaller percentage of heterozygous embryos (about 10%). Abnormal brain development and tail formation occur in homozygous mutants and are likely to be secondary to the neural tube defects. Disruption of F52 in mice therefore identifies a gene whose mutation results in isolated neural tube defects and may provide an animal model for common human neural tube defects.

Animals↗
PubMedDate not supplied

Neural tube defects: a primary prevention role for nurses.

Neural tube defects are among the most common and serious birth defects. Most of these defects are caused by multifactorial inheritance. Research over the past decade has led to advances in understanding the etiology of these congenital anomalies. Folic acid has been shown to reduce the risk of first-time occurrence of neural tube defects as well as recurrent risk. Other genetic and environmental factors are under investigation. In this article, the nurse's role in the primary prevention of these birth defects is described.

Female↗
PubMed1999

The incidence of nephrolithiasis in patients with spinal neural tube defects.

PURPOSE: Bladder stones are common in patients with spinal neural tube defects but there are little data on the incidence of renal calculi in this population. We examined the incidence, nature and risk factors of nephrolithiasis in our clinic population of patients with neural tube defects. MATERIALS AND METHODS: We retrospectively reviewed the charts and radiological studies of 327 patients followed at our neural tube defects clinic with routine radiological imaging of the urinary tract. Additional confirmatory studies were performed when stones were noted. RESULTS: Renal calculi were identified in 20 patients with neural tube defects (6.1%). The incidence of nephrolithiasis increased with age. Renal stones were noted in 19 patients (10.7%) 12 years old or older. Management of the stones in these patients resulted in overall 53% stone-free and 87% recurrence rates after intervention. Major risk factors for new and/or recurrent renal stone formation were bacteriuria in 95% of the cases, lower urinary tract reconstruction in 80%, pelvicalicectasis in 70%, vesicoureteral reflux in 65%, a thoracic level spinal defect in 60% and renal scarring in 55%. CONCLUSIONS: These data suggest that there is a higher incidence of nephrolithiasis in patients with neural tube defects than in the general population and the risk of stone recurrence is also elevated. Most patients with stones had undergone lower urinary tract reconstruction. Other risk factors were bacteriuria, pelvicalicectasis, vesicoureteral reflux and a thoracic level neural tube defect.

Adolescent↗
PubMed1995

Looking for causes of neural tube defects: where does the environment fit in?

The neural tube defects anencephaly and spina bifida are important causes of infant mortality and morbidity. Recent studies suggest that many of these defects can be prevented by the periconceptional use of folic acid. At the same time, we do not know what causes most cases of neural tube defects and there is evidence to suggest that they are etiologically heterogeneous. Additional research needs to be directed toward the role of occupational and environmental exposures in the etiology of these defects. Importantly, studies need to examine embryologically and anatomically specific types of defects and develop accurate information on biologically relevant exposures. Exposures toward which attention needs to be directed include organic solvents; agricultural chemicals, including pesticides; water nitrates; heavy metals such as mercury; ionizing radiation; and water disinfection by products. We also recommend that additional attention be paid to mechanisms of neural tube closure and to the potential role of genetic heterogeneity in the absorption and metabolism of xenobiotics and in their effects on the neural tube.

Anencephaly↗
PubMed1983

Ontogeny and adult behavior of mice with congenital neural tube defects.

Effects of abnormal neural tube development were studied in immature and adult mice. The behavior of affected adult mice was found to resemble that of mice that exhibit the "waltzer syndrome." Behavioral ontogenetic studies indicate that effected mice are deficient in labyrinthine responses as shown by the late development or lack of negative geotaxic behaviors and the delayed loss of pivoting behavior. Retarded maturation of neural responses was indicated by a delay in the appearance of the startle response. Evidence that circling behavior in adult mice of the "waltzer syndrome" may be a result of central nervous system disorders alone, or in concert with abnormalities of the inner ear, was provided by the fact that open field activity was increased in affected mice that exhibit circling behavior as adults.

Age Factors↗
PubMed1989

Dietary folate as a risk factor for neural-tube defects: evidence from a case-control study in Western Australia.

A population-based case-control study was conducted to test the hypothesis that the risk of the occurrence of neural-tube defects in infants with no other birth defects (isolated neural-tube defects) is associated inversely with the maternal dietary intake of free and/or total folate in early pregnancy. Information was collected from the mothers of 77 case subjects with isolated neural-tube defects who were born in Western Australia from 1982 to 1984, from the mothers of 77 control subjects with birth defects other than neural-tube defects (control group 1) and from the mothers of 154 control subjects with no birth defects (control group 2). The case and control subjects were matched individually by the date of the mother's last menstrual period. Odds ratios were adjusted for a number of potentially-confounding variables, such as the country of birth of the parents, paternal social class, previous pregnancy outcome, interval between index and previous pregnancy and pregnancy order. Crude and adjusted odds ratios showed a protective effect of an increasing intake of free folate in the first six weeks of pregnancy. Adjusted odds ratios, with reference to the lowest quartile of intake, (and their 95% confidence intervals) were 0.72 (0.25-2.08), 0.37 (0.11-1.23) and 0.31 (0.10-0.97) for quartiles 2-4 when control group 1 was used, and 0.44 (0.17-1.13), 0.34 (0.13-0.90) and 0.16 (0.06-0.49) when control group 2 was used. Similar, but weaker, trends were seen when total folate intake was the exposure variable. These findings support the hypothesis that the dietary intake of folate in early pregnancy protects against the occurrence of isolated neural-tube defects in infants. Measures of postpartum dietary folate and of postpartum serum and red-cell folate levels showed no association with the occurrence of neural-tube defects in infants.

Diet↗
PubMed1979

Antenatal diagnosis of neural tube defects in Canada: extension of a collaborative study.

Experience with the diagnosis of neural tube defects from alpha1-fetoprotein (AFP) concentrations in amniotic fluid is reported from a prospective study of five laboratories testing for 13 Canadian genetic centres. The results of the study indicate that antenatal diagnosis of open neural tube defects is being carried out effectively in Canada (in 99.2% of cases the AFP measurements were interpreted correctly). Amniocentesis should be recommended to women at high risk for having a child with a neural tube defect (i.e., those who have a child, a parent or a sibling with a neural tube defect). The rate of neural tube defects in 182 high-risk pregnancies was 2.2% for an open defect and 1.1% for a closed defect, whereas the rate in 673 pregnancies in which amniocentesis was being performed for other reasons was 0.3%. This suggests that the AFP concentration should be measured in any sample of amniotic fluid collected for other reasons (usually fetal karyotyping). There were three instances of false-negative results, for a rate of 0.4%. Two closed neural tube defects were not detected; this limitation of the test has also been found by others. One of the six fetuses with an open neural tube defect, who died in utero, had a large myelocele in the neck that was not recognized. There were also four instances of false-positive results, for a rate of 0.5%. The findings suggest that AFP values that are more than 2 but less than 7 standard deviations (SDs) above the mean may indicate a neural tube defect, and that values 7 or more SDs above the mean very likely indicate such a defect, although other reasons for such high values (e.g., fetal erythrocytes in the amniotic fluid, intrauterine death and mistaken gestational age) must be ruled out by other methods.

Amniocentesis↗
PubMed2006

Are encephaloceles neural tube defects?

OBJECTIVE: Encephalocele is classified as a neural tube defect, but questions have been raised regarding whether its epidemiological characteristics are similar to those of other neural tube defects. DESIGN: We compared characteristics of temporal trends in, and the impact of folic acid grain fortification on, the prevalence of encephalocele, spina bifida, and anencephaly using data from the Metropolitan Atlanta Congenital Defects Program, a population-based birth defects surveillance system. Prevalences of encephalocele, spina bifida, and anencephaly were compared by maternal age, gender, race, birth weight, ascertainment period (1968-1981, 1982-1993, or 1994-2002), and fortification period (1994-1996 [prefortification] and 1998-2002 [postfortification]) using prevalence ratios with 95% confidence intervals. Temporal trends were assessed using Poisson and negative binomial regression models. RESULTS: Prevalence rates of encephalocele (n = 167), spina bifida (n = 650), and anencephaly (n = 431) were 1.4, 5.5, and 3.7 per 10 000 live births, respectively. Encephalocele was similar to anencephaly in showing an increased prevalence among girls and multiple gestation pregnancies and to spina bifida and anencephaly in an annual prevalence decrease between 1968 and 2002 (-1.2% for encephalocele, -4.2% for spina bifida, and -3.6% for anencephaly). With fortification, prevalence decreased for spina bifida but not significantly for encephalocele or anencephaly. CONCLUSIONS: Encephalocele shows more similarities to spina bifida or anencephaly than it shows differences with respect to characteristics, temporal trend, and impact of fortification. Additional studies should be done to explore the etiologic heterogeneity of encephalocele using better markers of folate status and a wider range of risk factors.

Adolescent↗
PubMed1983

[Genetic counseling and prenatal diagnosis in families with neural tube defects].

An analysis of 141 families with children with neural-tube defects was performed. The families were consulted in the Department of Genetics, the Institute of Mother and in Child the period between 17.01.1978 and 29.02.1980. The family histories were obtained from the parents. The diagnosis was established on the basis of autopsy data and/or medical records. In cases of multiple congenital malformations coexisting with a neural-tube defect the precise diagnosis of the syndrome was established after a thorough search of the medical literature. Analysis of the material, showed that in 10 families (6,5%) neural-tube defect was associated with other malformations. There were 5 cases of sporadic syndromes (cloacal extrophy-2, aberrant tissue bands-2, sacrococageal teratoma-1), 3 families with Meckel's syndrome and 2 cases in which the nature of the syndrome was not determined. In 131 families the neural-tube defect was isolated and multifactorial inheritance was assumed (table VII). 113 families were given information about the cause of malformation, risk of recurrence, possibility of prenatal diagnosis and indications for amniocentesis (estimation of alpha-foetoprotein in amniotic fluid). After receiving genetic counseling and being fully informed about prenatal diagnosis the parents were asked about their procreative plans and their attitude to amniocentesis. Out of these families 74,3% planned next pregnancy (table IX), 57,6% wanted to have prenatal diagnosis (table VI). 131 family histories (probands with isolated neural-tube defect) were reviewed to determine recurrence risk for relatives. The recurrence risk for sibs was found to be: 4,9% (table III) and was higher than the expected risk (3,4%) from the population incidence of neural-tube defects in Poland (1, 15/1000 births including stillbirths). The recurrence risk for second and third degree relatives was found to be 0,1% (table IV) and 0,3% (table V) respectively.

Adolescent↗
PubMed1975

Prenatal diagnosis of a neural tube defect: Meckel syndrome.

A severe neural tube defect diagnosed in a 191/2-week-old "at risk" fetus on the evidence of a markedly elevated alpha-fetoprotein level in the amniotic fluid, turned out to be an occipital myelocoele. However, the fetus also had polycystic kidneys and postaxial hexadactyly on all extremities. The karyotype was normal. These are the features of the rare Meckel syndrome, caused by a pleiotropic, autosomal, recessive gene, and one and possibly two other sibs were also affected.

Abnormalities, Multiple↗