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At least 19 recordsLinked to original sources
PubMed1984

Investigation of area differences in the prevalence at birth of anencephalus in Belfast.

A retrospective case-control study comparing social and biological factors relating to all stillbirths and liveborn infants with anencephalus (n = 433) and a 10% random sample of all livebirths (n = 107 346) born to women resident in Belfast between 1957 and 1969 was carried out. The aim was to determine whether the large difference in the prevalence rate at birth of anencephalus within this city could be explained by any previously identified risk factors. For the 15 electoral wards the average rate over the study period was lowest in Windsor ward and highest in Court ward--rates 2.7 and 8.0 per 1000 livebirths respectively. Also, for one particular group of women who lived in certain areas of Belfast and who had an abnormal reproductive history the anencephalic rate was between 7.1 and 10.1 per 1000 livebirths depending on their parity. Although reproductive history was significantly associated with the risk of anencephalus this did not explain the area differences in rates within the city. These findings together with other work suggest that there are at least two separate sets of factors influencing the occurrence of anencephalus. One set relates to area of residence and may reflect adverse social circumstances and diet; the second set relates to maternal reproductive history, acts largely independently of the first and may have a genetic basis. Although this hypothesis accounts for a number of observations relating to anencephalus the excess of affected females cannot be adequately explained.

Adult↗
PubMed1993

The prevalence of anencephalus and spina bifida in New Zealand.

Despite the plethora of epidemiological research conducted on anencephalus and spina bifida, few of the studies have used multiple source case ascertainment and controlled for the effect of possible confounding factors. This paper reports the results from a study of the relationships between various risk factors and the prevalence of anencephalus and spina bifida in New Zealand during 1978-82, using case data obtained from multiple sources and a national cohort of births as the denominator. The rates of anencephalus and spina bifida in New Zealand were 0.78/1000 and 0.94/1000 total births, respectively. The rate of a neural tube defect (NTD) birth for Maori parents was less than for their non-Maori counterparts. Paternal ethnic origin and maternal ethnic origin made similar contributions to the model of anencephalus rates, but the results suggest that paternal ethnic origin is a less important risk factor in the prevalence of spina bifida. The rate of both NTD was high among female infants and low among births to women born in countries other than the British Isles and New Zealand. The rate of anencephalus showed a distinct north-south gradient, but there was no evidence of effects for maternal or paternal age, parity, urban-rural place of residence, nuptiality, social class or season of birth in the prevalence of either NTD in New Zealand.

Adult↗
PubMed1986

Risk factors in the prevalence of anencephalus and spina bifida in New Zealand.

This paper presents results from an epidemiological study on the 51 anencephalus and 53 spina bifida cases in the 1978 New Zealand birth cohort. Multiple sources were used in the ascertainment, and the prevalence rates were 0.98 and 1.02 per 1,000 total births, respectively. No association was found with the traditional indicators of the effect of environmental factors: maternal age, social class, nuptiality, month of birth, or estimated month of conception. Males comprised 41% of anencephalus and 36% of spina bifida cases; the prevalence was higher in the non-Maori than in the Maori population. New Zealand-born mothers appear to have a much lower risk of spina bifida, but not anencephaly, than those born in England/Scotland. The rate for the latter population was within the range of a number of UK-based studies. As the bloodstock of New Zealand whites has been predominantly derived from the UK population, and as New Zealand is a low prevalence area, this suggests that the higher risk for these women is likely to be attributable to factors present in their birthplace but absent in New Zealand. These findings provide further evidence that the epidemiologic patterns of anencephalus and spina bifida in low-prevalence areas are at variance with those in high-prevalence areas, such as the United Kingdom. They also support the hypothesis that the contrast in rates between high- and low-prevalence areas is a reflection of the impact of environmental factors in high-prevalence areas on the "background" or baseline frequency of anencephalus and spina bifida found in low-prevalence areas.

Adult↗
PubMed1983

A population-based case-control study of anencephalus and spina bifida in a low-risk area.

For the period 1973 to 1977, a total of 536 cases of anencephalus and spina bifida were ascertained in Los Angeles County, California, a low-risk area, and compared with a 2 per cent random sample of all live births in the county. Women with Spanish surnames had an elevated risk for anencephalus and to a lesser extent for spina bifida; Blacks were at lowest risk, especially for spina bifida. The occurrence of a previous fetal death was a strong risk factor for anencephalus but there was no association between socio-economic status and either of the defects. Advanced maternal age was a stronger risk factor for spina bifida than for anencephalus but, as in other studies in low-risk areas, no increased risk was observed among teenage mothers. Paternal age did not show any independent association after controlling for mother's age. Finally, the association of high birth-order with the birth defects was weakened greatly after simultaneous adjustment for age and ethnicity.

Analysis of Variance↗
PubMed1986

[Anencephalus immunogenetic factor].

The T/t complex in the mouse is considered to be a gene locus that brings about neural tube defects. This locus is found to exist near the H-2 complex, which is the MHC of the mouse. Accordingly, it is conceivable that there exists a T/t-like complex near the HLA complex in humans. Studies on the HLA-A, -B, -DR, -DRw52, -53 and DQ loci of parents with anencephalus and affected offspring were undertaken with the aim of revealing the relationship between anencephalus and the HLA complex. The following results were obtained: The gene frequency of HLA-DR5 in a mother with anencephalus was significantly higher than in controls. HLA-DR materno-paternal compatibility was significantly higher than in control couples. An increase in HLA-DR, -DRw52, -53 and DQ homozygosity were observed among the affected offspring. These results indicated that there may exist an anencephalus immunogenetic factor in the HLA-D region.

Adult↗
PubMed1982

International variation in the prevalence at birth of anencephalus in relation to maternal factors.

Information from series of cases of anencephalus and corresponding random samples of all livebirths showed that the prevalence rate at birth per 1000 livebirths for anencephalus was 4.02 in Belfast (from 1957 to 1969), compared to 1.36 in mothers of Scots-Irish origin resident in 14 selected Canadian cities (from 1950 to 1969). For each of these two populations, anencephalus was associated with the number of previous livebirths, stillbirths, and child deaths. However, these maternal factors did not account for any appreciable portion of the difference in prevalence rates between the two populations, showing that a different set of factors must cause the international difference in rates.

Adolescent↗
PubMed1980

A family study of spina bifida and anencephalus in Belfast, Northern Ireland (1964 to 1968).

The parents of 226 of the 360 patients with anencephalus or spinal bifida or both, born in Belfast 1964 to 1968, were visited to document the occurrence of these malformations among other relatives. The proportions of sibs with anencephalus and spina bifida were 10.41% for spina bifida index patients and 6.4% for anencephalus. For patients born after the index patients, the proportions were 12.19% and 6.35%, respectively. The overall incidence of either malformation among sibs was 8.87%. This estimate is higher than the 4 to 5% commonly reported and is probably related to the specific background of the Northern Ireland population, which is known to have the highest incidence of CNS malformations in the United Kingdom. The substantial size of this risk indicates the importance of amniocentesis for monitoring subsequent pregnancies of women who have had one child with a CNS malformation.

Anencephaly↗
PubMed1981

Discordant anencephalus in a Pergonal-induced triplet pregnancy.

A patient with a triplet pregnancy had one infant affected by anencephalus. This pregnancy resulted from ovulation stimulation by gonadotropins. Several cases of association between anencephalus and induction of ovulation by clomiphene have been reported. The association with gonadotropins, however, has been reported only once. The event was prenatally diagnosed by ultrasound studies in the first and second trimesters. The association of anencephalus with ovulation stimulation is discussed briefly.

Adult↗
PubMed1993

[Apparent decrease in the occurrence of anencephalus in Norway 1967-90].

The occurrence of anencephalus as reported to the Norwegian Medical Birth Registry has fallen from 4.9 per 10,000 births in 1967-71 to 2.7 in 1987-90. The decrease is particularly noticeable for births with a gestational length of 28 weeks or more. On the other hand, there has been a significant increase in the number of cases of anencephalus with a gestational age less than 28 weeks. The occurrence of meningomyelocele has remained relatively stable throughout the same period. Ascertainment error could explain these contrasting trends, since cases of anencephalus detected on ultrasound screening may lead to early termination of pregnancy without notification to the Medical Birth Registry. Better routines for notification of malformations are needed to improve the basis for surveillance in Norway.

Anencephaly↗
PubMed1977

Anencephalus and drinking water composition.

The mortality rate (stillbirths and infant deaths) from anencephalus from 1950-1969 in 36 cities of over 50,000 population in Canada showed a negative association (r = -.39) with the concentration of magnesium in water sampled at domestic taps. The mortality rates showed negative associations with mean income and longitude, and a multiple regression model using the three factors showed significant effects of each and accounted for 69% of the intercity variation in rates. There were no significant associations seen with water calcium concentration or total hardness. Income, magnesium and longitude were also negatively associated with mortality rates from spina bifida, hydrocephalus, other congenital abnormalities, and total stillbirth and infant death rates, but the association with magnesium was significant only for total stillbirths. The negative association of anencephalus mortality and magnesium levels was also seen in a sample of 14 smaller towns in Ontario.

Anencephaly↗
PubMed1981

Water composition in the etiology of anencephalus.

This case-control study was based on 468 deaths from anencephalus and a random sample of 4129 livebirths occurring during 1969 to 1972 to mothers resident in 142 localities of over 10,000 population in Canada. Anencephalus risk was associated with the previous pregnancy history of the mother, with legitimacy, year of birth and with the longitude of the mother's residence, but after adjusting for these there was no significant association seen with locality population size, mean income, the proportion of women employed, latitude, or with the concentrations in drinking water of any of 14 elements: calcium, magnesium, copper, lithium, zinc, nickle, lead, selenium, mercury, chromium, silver, cobalt, cadmium and molybdenum.

Anencephaly↗
PubMed1976

Anencephalus in the Oxford Record Linkage Study area.

The incidence of anencephalus in the largely rural areas of Oxfordshire and west Berkshire from 1965 to 1972 was ascertained from the files of the Oxford Record Linkage Study as 1-49 per 1000 total births. There was little variation within the area, but there was a marked increase in incidence over the eight years of the study. There was a slight seasonal variation, with an excess of conceptions in the first two quarters of the year, a slight excess of births to primiparous women and to women aged between 20 and 24 years. There was an increase in incidence with falling social class, with a significant excess of fathers who were printers, painters and decorators, transport drivers or in the armed forces. Among 115 siblings, 11 (9-6 per cent) had defects of the central nervous system, and the incidence of anencephalus among twins was twice as high as expected.

Abortion, Spontaneous↗
PubMed1975

Seasonal variation in anencephalus in Canada.

A study of the monthly numbers of stillbirths and of deaths due to anencephalus in Canada from 1954 to 1962 showed a weak tendency to a winter excess of affected births. The seasonal trend was more marked in the Prarie provinces and in Quebec than elsewhere; the maximum rate of anencephalus occurrence was in October to December in the Prairies and in British Columbia, and in January to March in other regions.

Anencephaly↗
PubMed1976

Anencephalus, Spina Bifida, twins, and teratoma.

The twin pairs with spina bifida and or anencephalus collected from the literature by Rogers and Weatherall (1976) form the basis for an argument that the apparent rarity of dizygous twins concordant for these malformations may be due to the breakdown of the interamniotic partition and a subsequent fetus-fetus interaction. It is suggested that this may lead to complete or partial destruction of one twin. When cells survive they may form teratoma or patches of anomalous skin cover. The hypothesis that monozygous twins concordant for these defects may form double monsters is re-stated. The present hypothesis predicts that the incidence of pineal and intraspinal teratoma will vary in time and place with anencephalus and spina bifida, and that the scalp type hairs found over or around spina bifida may prove, in male infants, to have female chromosomes.

Abnormalities, Severe Teratoid↗
PubMed1981

The incidence of anencephalus in the Fylde peninsula 1956-76 and changes in water hardness.

In an area which had a high incidence of anencephalus, 3.2 per 1000 births, there was a significant drop to 1.3 per 1000, below the national average of 1.7 to 1.8, among conceptions after 1967. In the northern part of the area this drop was greater in summer than winter conceptions, providing additional evidence of a different process underlying case occurrences in the north of the area from that in the south. In 1957-61 there were significantly more births of anencephalic babies in North Fylde than in South Fylde, but both areas were supplied with soft water. From 1962 to 1969 the water changed from soft to slightly hard. Soft water does not appear to be a primary aetiological factor in anencephalus, but hard water may mitigate the effect of other factors.

Anencephaly↗
PubMed1979

Klippel-Feil syndrome, iniencephalus, anencephalus, hindbrain hernia and mirror movements: overdistention of the neural tube.

Bony anomalies encountered in the 'no neck' form of Klippel-Feil syndrome (KFS) are a wide, short, fused, bifid, retroflexed spinal canal; craniolacunia, cranium bifidum, and acrania. The only symptom may be mirror movement (MM). The CNS anomalies are hindbrain hernia, hydrocephalus, hydromyelia, syringomyelia, meningocele, myelocele, encephalocele, and anencephalus. In severe KFS, i.e. iniencephalus (IN) and in anencephalus (AN), the inion is in contact with the back. In both there is hindbrain hernia and the left thorax may contain the stomach tethered to an anterior spina bifida. KFS results from distortion of somites by an overdistended neural tube. A neural tube that fails to close cannot overdistend.

Adolescent↗
PubMed1988

Incidence of anencephalus and spina bifida in Greece.

A cross-sectional national survey of 11,048 births in the whole of Greece in April 1984 identified 7 cases of anencephalus and 9 of spina bifida. There was thus an incidence of 1.45 neural tube defects per 1,000 total births. This is the first geographically defined population study from southern Europe. In comparison with hospital-based data from the 2 countries on its borders, the Greek rates are rather similar to those of Yugoslavia but much lower than reports from Turkey.

Anencephaly↗