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Periconceptional vitamin supplementation and neural tube defects; evidence from a case-control study in Western Australia and a review of recent publications.

STUDY OBJECTIVE: The aim was to assess the association of neural tube defects with periconceptional vitamin supplementation. DESIGN: This was a matched, population based case-control study. SETTING: Western Australia, 1982-1984. PARTICIPANTS: Mothers of 77 cases (93% of those eligible) with isolated neural tube defects, mothers of 77 matched control infants with defects other than neural tube defects (control group I), and mothers of 154 liveborn, matched, control infants with no birth defects (control group II) participated in the study. MEASUREMENTS AND MAIN RESULTS: Information was collected by interview and self administered questionnaire. Crude and adjusted odds ratios (and their 95% confidence intervals) showed a small but non-significant protective effect of folate supplementation in comparisons with both control groups. The adjusted ratios for the three months before pregnancy were 0.69 (0.06, 8.53) with control group I, and 0.11 (0.01, 1.33) with control group II. In the first six weeks of pregnancy, the adjusted odds ratios were 0.70 (0.32, 1.52) with control group I and 0.74 (0.29, 1.88) with control group II. The odds ratios for vitamin supplementation of any kind were all very close to or greater than one, and all confidence intervals embraced unity. CONCLUSIONS: These data do not provide evidence of an association between periconceptional vitamin supplementation and neural tube defects, although a protective effect of folate supplementation cannot be excluded with confidence, due to the low power of the study. Of three other observational studies of vitamins and neural tube defects, two have shown an association. While further studies of this kind may be of value, evidence must now be sought from randomised controlled trials.

Case-Control Studies

Congenital urinary abnormalities and neural tube defects.

The records of 178 children with a neural tube defect were reviewed to determine the pattern of associated congenital urinary malformation. Ten (6%) of the children had a significant congenital urinary malformation. Although unilateral renal agenesis was the most common single congenital urinary abnormality, as a group, abnormalities in fusion or migration were equally common in this study and more common in several previously reported studies. Lower congenital urinary tract abnormalities were also identified but were less common. No correlation was found between the level of the neural tube defect and the specific congenital urinary abnormality.

Child

Spectrum of neural-tube defects in 34 infants prenatally exposed to antiepileptic drugs.

We analyzed the spectrum of neural-tube defects associated with maternal exposure to antiepileptic drugs (AEDs) and the possible contribution of familial and genetic factors to epilepsy or neural-tube defects. No specific association with maternal family history of neural-tube defects or epilepsy was seen. The ratio of spina bifida to anencephaly (33:1) suggested a specific association with caudal defects. Hydrocephaly was documented in at least 21 cases. Other midline defects, all associated with valproate (VPA), were hypospadias (two), hypertelorism (two), partial agenesis of corpus callosum, agenesis of septum pellucidum with lissencephaly of medial sides of occipital lobes, Dandy-Walker anomaly, and ventricular septal defect. This study shows that most neural-tube defects following maternal VPA use are severe open defects. They are frequently complicated by hydrocephaly and other midline defects. Prenatal diagnosis is possible.

Anticonvulsants

An epidemiologic study of neural tube defects: Delta County, Michigan, 1969-1988.

We determined the incidence of neural tube defects (anencephaly, spina bifida, hydrocephalus) in a rural county in the Upper Peninsula of Michigan because several local physicians perceived that the incidence in this area might be high. To assure that all neural tube defects that occurred were noted, data for the study were collected from hospital birth-log books, patient records of all neural tube defect births, all stillbirth records, and from records of babies transferred to other regional hospitals. A reference group consisting of 10% of all nonneural tube defect births during the 20 years of the study was selected at random and used to make comparisons to the case group. During the twenty-year period 1969-1988, the incidence of neural tube defects (NTDs) was found to be 2.09 per 1000 total births. The incidence of anencephaly was 1.05/1000; of spina bifida, 0.56/1000; and for hydrocephalus, 0.48/1000. Seasonal variations by month of conception were noted for anencephaly and spina bifida, confirming previous findings in the literature. Study results showed that between 1972 and 1976 there was a cluster of NTDs, but the NTD incidence was not statistically different from what might be expected over a twenty-year period. The incidence of NTDs in Delta County was found to be normal for this part of North America. The results of this study indicate that physicians should be cautious when attempting to interpret rare events, which often occur in clusters, leaving the impression that their incidence is excessive.

Adult

Amniotic fluid alpha-fetoprotein as a marker in prenatal diagnosis of neural tube defects.

The prenatal diagnosis of anencephaly and spina bifida (neural tube defect, NTD) through amniotic fluid analysis for alpha-fetoprotein (AFP) is gradually gaining clinical recognition. AFP concentrations were determined in 237 amniotic fluids from normal pregnancies ranging between 7 and 42 weeks of gestation. A steady decline in AFP from 26 mug/ml at 7-9 weeks to 155 ng/ml at term is observed. AFP concentration was determined in 35 amniotic fluids from 33 confirmed neural tube defective pregnancies. In 14 cases where amniotic fluid was examined prior to the 26th week of gestation. AFP was markedly elevated when compared with the normal range of the same gestational period. In 21 amniotic fluids past the 26th week, 17 cases (85-) had markedly elevated AFP levels; however, 2 cases of anencephaly, 1 of spina bifida, and 1 of hydrocephaly gave levels within the normal range. It is concluded that elevated AFP in the amniotic fluid is a reliable but nonspecific marker for open neural tube defects prior to the 26th week of pregnancy, but may become normal after the 26th week in a small percentage of patients.

Amniotic Fluid

A sonographic sign which predicts which fetuses with hydrocephalus have an associated neural tube defect.

We report a sonographic sign which reliably distinguishes those hydrocephalic fetal heads associated with a neural tube defect from those which are not, particularly in the second trimester. This sign involves a "pointed" deformity of the frontal aspect of the skull in fetuses with hydrocephalus, indicating the presence of a neural tube defect. A retrospective review of 36 cases of hydrocephalus demonstrates that this sign is particularly helpful in the second trimester, where it was present in all the fetuses with hydrocephalus and neural tube defect. It was less reliable in the third trimester; however, this sign was not present in any of the fetuses with hydrocephalus who did not have a neural tube defect. Angulation or pointing of the fetal frontal bone when hydrocephalus is present, particularly in the second trimester, seems to be a reliable predictor of an associated neural tube defect and mandates a careful search for this defect.

Female

Recurrent neural tube defects, risk factors and vitamins.

Data from our trial of periconceptional vitamin supplementation for the prevention of neural tube defects have been analysed to assess the influence of various factors on recurrence rates of neural tube defect. Our data suggest that the risk of recurrence of neural tube defect is influenced by the number of previous neural tube defects, area of residence, immediately prior miscarriage, and interpregnancy interval. None of these factors, however, contributed any significant differential risk between supplemented and unsupplemented mothers. Hence we conclude that the highly significant difference in recurrence rates of neural tube defect between supplemented and unsupplemented mothers was due to vitamin supplementation.

Abortion, Spontaneous

Spinal ganglia reduction in the splotch-delayed mouse neural tube defect mutant.

Splotch and splotch-delayed mutants have anomalies in certain neural crest cell derivatives as well as neural tube defects. A genetic marker was used to identify mutant, heterozygote, and wild-type embryos within a litter, which enabled us to make intergenotypic comparisons. Histological studies of the lumbosacral region of day 15 and day 16 embryos indicated that the splotch-delayed mutant had similar but less severe defects in spinal ganglion development than those reported for splotch (Auerbach: Journal of Experimental Zoology 127:305-329, 1954). The ganglia were extensively reduced in size, residual, or missing in the splotch-delayed mutant, whereas in the splotch mutant, they were virtually nonexistent. Paired comparison analyses showed that all mutant embryos had a significant reduction in their volume of lumbosacral spinal ganglia when compared to their heterozygous and/or wild-type littermates. Also, some heterozygotes were found to have spinal ganglia volumes that were significantly reduced when compared to wild-type embryos. The volume of spinal ganglia was not related to the severity of the neural tube defect. In fact, three mutant embryos, which did not exhibit a neural tube defect, had spinal ganglia volumes comparable to or less than those mutants with open neural tube lesions or curly tails. This shows that the formation of abnormal neural crest cell derivatives is not a result of the neural tube closure defect. We hypothesize that the two anomalies observed in these mutants have a common etiological basis.

Animals

Neural tube defects in trisomy 18.

In a retrospective survey, the incidence of neural tube defects in liveborn trimsomy 18 was found to be 6.2 per cent. Based on these data one would expect to find trisomy 18 in 1 of the 117 patients with myeloidysplasia; the incidence of trisomy 18 in dysraphic fetuses would be anticipated to be higher. These observations underscore the need for amniocentesis karyotyping of fetuses with neural tube defects, and the importance of careful examination of infants born with neural tube defects.

Adult

Neural tube defects in rural Ireland.

The incidence of neural tube defects in a rural area of the west of Ireland from 1974 to 1985 was 2.96 per 1000. The prevalence was unchanged during the 11 years. When compared with a control group there was no increased incidence of anaemia in mothers of affected infants.

Female

[Etiologic and epidemiologic aspects of neural tube defects].

A case-control study of neural tube defects (NTD) was undertaken from 1979 to 1986 in the department of Bas-Rhin in Northeastern France. For 105,374 consecutive births the incidence of spina bifida was 0.62 in 1,000, the incidence of anencephaly was 0.33 in 1,000 and that of encephalocele was 0.14 in 1,000. Sex ratios were respectively 1.06, 0.64 and 0.75. Among the numerous etiological factors which were studied we observed a seasonal factor (more conceptions in April, less in September). Birth weight and length were lower in children with spina bifida than in controls. Metrorrhagia was more frequent during pregnancies with anencephaly as was oligoamnios in pregnancies with encephalocele. Routine US prenatal diagnosis, which was performed in 90% of the pregnant women, allowed diagnoses in 88% of the fetuses with anencephaly but only in 53% of the fetuses with spina bifida and in 64% of the fetuses with encephalocele. For these last two anomalies diagnosis could often be performed because a malformation was associated with a NTD.

Female

Periconceptional use of multivitamins and the occurrence of neural tube defects.

We studied the association between multivitamin use during the periconceptional period and the occurrence of neural tube defects using data from the Atlanta Birth Defects Case-Control Study. There were 347 babies with neural tube defects who were live born or stillborn to residents of metropolitan Atlanta from 1968 through 1980. The 2829 control-babies born without birth defects were randomly selected through birth certificates. Periconceptional multivitamin use was defined as reported use for each of the three months before conception through the first three months of pregnancy. Mothers who reported not using multivitamins any time during the six-month period were defined as nonusers. Fourteen percent of mothers reported periconceptional multivitamin use and 40% reported nonuse. Multivitamin users were different from nonusers in a number of demographic, health-related, and life-style characteristics. We found an overall apparent protective effect of periconceptional multivitamin use on the occurrence of neural tube defects, with a crude estimated relative risk of 0.40 (95% confidence interval, 0.25 to 0.63). At this time, it is not possible to determine whether this apparently lower risk is the direct result of multivitamin use or the result of other characteristics of women who use multivitamins.

Adult

National strategies for screening neural tube defects in Saudi Arabia: activating prevention and early intervention.

BACKGROUND: Neural tube defects (NTDs) are serious congenital anomalies affecting the brain and spinal cord. Despite widespread folic acid supplementation and food fortification programs, regions such as Saudi Arabia have not experienced a proportional decline in NTD prevalence. This narrative review evaluates the multifactorial contributors to NTDs, focusing on the effectiveness of current prevention and screening strategies both globally and within Saudi Arabia. MATERIALS AND METHODS: A comparative methodology guided this review, drawing from studies published between 2000 and 2024 sourced from PubMed, Scopus, and the WHO library. Keywords included "neural tube defects," "folic acid supplementation," "screening programs," and "food fortification." While not a systematic review, PRISMA principles were loosely followed to ensure study relevance and rigor. RESULTS: Globally, countries like the United States, Canada, Chile, and Australia have implemented mandatory folic acid fortification and reported NTD reductions ranging from 19 to 78%. South Africa, for example, achieved a 66% decline in NTD-related deaths post-fortification. In Saudi Arabia, similar initiatives have been launched, including folic acid campaigns and food fortification. However, national-level data evaluating their impact remains sparse. Regional disparities in implementation, awareness, and access have limited the success of these measures. Although 80.1% of Saudi women reportedly understand the preventive role of folic acid, uptake and proper timing of supplementation remain inconsistent. Screening services, particularly in rural areas, are not uniformly accessible, reducing early detection rates. Unlike countries such as Australia and Chile, Saudi Arabia lacks a standardized system for tracking and evaluating NTD outcomes. CONCLUSION: This review concludes that while Saudi Arabia has adopted commendable preventive strategies, the absence of comprehensive data, policy enforcement, and public education limits their effectiveness. Strengthening national monitoring systems, ensuring equitable access to screening, and enforcing mandatory fortification policies modelled on successful international practices are critical. Adopting evidence-based policies supported by robust evaluation frameworks will be essential to reducing the burden of NTDs and improving maternal and child health outcomes in Saudi Arabia.

Humans

Biomechanical basis of diazepam-induced neural tube defects in early chick embryos: a morphometric study.

The biomechanical basis of diazepam (Valium/Roche)-induced neural tube defects in the chick was investigated using a combination of electron microscopy and morphometry. Embryos at stage 8 (four-somite stage) of development were explanted and grown for 6 hr in nutrient medium containing 400 micrograms/ml diazepam. Nearly 80% of these embryos exhibited neural tube defects that were most pronounced in the forming midbrain region and typified by a "relaxation" or "collapse" of neural folds. The hindbrain and spinal cord regions were less affected. Electron microscopy revealed that neuroepithelial cells in diazepam-treated embryos had smoother apical surfaces and broader apical widths than did controls. Morphometric measurements supported this observation and further showed that these effects were focused at sites within the wall of the forming neural tube that typically exhibit the greatest degree of bending and apical constriction (i.e., the floor and midlateral walls). Overall results indicate that neural tube defects associated with exposure to diazepam are due largely to a general inhibition of the contractile activity of apical microfilament bundles in neuroepithelial cells. These findings 1) emphasize the important contribution of microfilament-mediated apical constriction of neuroepithelial cells in providing the driving forces for bending of the neuroepithelium during neural tube formation and 2) suggest that agents or conditions that impair their contractile activity could play a role in the pathogenesis of certain types of neural tube defects.

Animals

Multivitamin/folic acid supplementation in early pregnancy reduces the prevalence of neural tube defects.

We examined the relation of multivitamin intake in general, and folic acid in particular, to the risk of neural tube defects in a cohort of 23,491 women undergoing maternal serum alpha-fetoprotein screening or amniocentesis around 16 weeks of gestation. Complete questionnaires and subsequent pregnancy outcome information was obtained in 22,776 pregnancies, 49 of which ended in a neural tube defect. The prevalence of neural tube defect was 3.5 per 1000 among women who never used multivitamins before or after conception or who used multivitamins before conception only. The prevalence of neural tube defects for women who used folic acid-containing multivitamins during the first 6 weeks of pregnancy was substantially lower--0.9 per 1000 (prevalence ratio, 0.27; 95% confidence interval, 0.12 to 0.59 compared with never users). For women who used multivitamins without folic acid during the first 6 weeks of pregnancy and women who used multivitamins containing folic acid beginning after 7 or more weeks of pregnancy, the prevalences were similar to that of the nonusers and the prevalence ratios were close to 1.0.

Adult

Amniography in the prenatal diagnosis of neural tube defects.

Amniography for the visualization and confirmation of suspected neural tube defect was performed in 9 midtrimester gravidas. In all cases, amniotic fluid alpha-feto protein (AFP) was abnormally elevated. Four cases of anencephaly and one of spina bifida were demonstrated by amniography. These pregnancies were terminated and the defects were confirmed by gross pathologic examination. In 4 remaining cases, amniography was normal. Three of these pregnancies proceeded to term, culminating in the birth of a normal child. The fourth patient had spontaneous abortion of a normal fetus at 23 weeks of gestation. The experience reported here suggests that amniography is an important adjunctive diagnostic technique in the prenatal diagnosis of neural tube defect, and if used correctly, may significantly reduce the chance of false-positive diagnosis.

Adult