Anencephalus in Belfast. Incidence and secular and seasonal variations, 1950-66.

Elwood, Jannette

doi:10.1136/jech.24.2.78

Cited by 26 publications

(16 citation statements)

References 41 publications

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“…However, these results should be interpreted with caution as there is an overall long term downward trend in the data. In a previous Irish study 28 an April peak was also observed.…”

Section: Discussionsupporting

confidence: 50%

East Ireland 1980-1994: epidemiology of neural tube defects

McDonnell¹,

Johnson²,

Delaney³

et al. 1999

Journal of Epidemiology & Community Health

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Study objective-The objective of the study was to describe the epidemiology of neural tube defects (NTD) in the eastern region of Ireland using the EUROCAT register of congenital malformations. Design, setting and patients-EUROCAT registries monitor the prevalence of congenital anomalies in defined populations using multiple sources for case ascertainment. All cases of NTD on the Dublin EUROCAT register born between 1980 and 1994 were extracted and analysed. The crude birth prevalence rate for all NTD, spina bifida, anencephaly and encephalocoele were calculated for each year. Parameters measured were: sex ratio, stillbirth rate, proportion of low birthweight babies (<2500 g) and the proportion who were premature (<37 weeks gestation). Main results-Of 821 NTD cases, 419 (51.0%) had spina bifida, 322 (39.2%) had anencephaly, 69 (8.4%) had encephalocoele and 11 (1.3%) were iniencephalic. The crude birth prevalence of NTD decreased fourfold from 46.9/10 000 births in 1980 to 11.6/10 000 in 1994. The downward trend ceased during the early 1990s. Younger mothers had significantly higher rates of NTD aVected births. Twenty two per cent of NTD cases had additional non-central nervous system anomalies. In 40 cases, there was a previous family history of NTD in siblings. Seasonal eVects in birth prevalence were observed. Birth notification was the most frequent mechanism of ascertainment. Conclusion-There was a marked fall in the birth prevalence of NTD during the 15 year period. This change was real and not accounted for by pre-natal screening and diagnostic practises with termination of pregnancy, which is not legally permissible in Ireland. Dietary factors may have had an influence. Rates of NTD in this region are still higher than many other parts of Europe. Primary prevention strategies through increased folic acid intake are necessary to further reduce NTD aVected births. (J Epidemiol Community Health 1999;53:782-788) Neural tube defects (NTD) are major congenital abnormalities of the nervous system that result from incomplete closure of the developing neural tube early in pregnancy. Anencephaly, spina bifida and encephalocoele account for almost all NTD. Ireland and other Celtic countries of the British Isles are known to have high prevalence rates of NTD compared with other parts of Europe.

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“…However, these results should be interpreted with caution as there is an overall long term downward trend in the data. In a previous Irish study 28 an April peak was also observed.…”

Section: Discussionsupporting

confidence: 50%

East Ireland 1980-1994: epidemiology of neural tube defects

McDonnell¹,

Johnson²,

Delaney³

et al. 1999

Journal of Epidemiology & Community Health

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“…There are many reports of a winter excess of the births of children with CNS defects, especially anencephaly (Edwards 1958;Leck and Record, 1966;Elwood, 1970;Wilson, 1971). In a report from Scotland (Elwood and MacKenzie, 1971) there was a significant winter excess for anencephaly in Glasgow but a summer excess in Aberdeen.…”

Section: Discussionmentioning

confidence: 99%

Defects of the central nervous system in Finland: I. Variations in time and space, sex distribution, and parental age.

Granroth¹,

Hakama²,

Saxén³

1977

Journal of Epidemiology & Community Health

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SUMmARY Data from the Finnish Register of Congenital Malformations for the years 1965-73 were used in a search for associations between environmental influences and defects of the central nervous system (CNS). The material consisted of 710 cases of CNS defects and their matched-pair controls. Moreover, an 'internal' control group of 259 cases of polydactyly and their matched-pair controls were used. The first report gives information on variations in time and space, sex distribution, and parental age. A higher incidence of anencephaly was noted in the eastern part of the country, but no significant secular or seasonal variations were found. The sex ratio (M/F) was lower than expected in the groups of anencephaly and CNS defects as a whole. High parental age turned out to be a risk factor in the group of all CNS defects, mainly owing to the subgroup of hydrocephaly. The dangers of observational studies due to confounding factors are discussed.Defects of the central nervous system (CNS) constitute an important medical as well as a social problem which like most congenital defects are likely to be caused by an interaction of both genetic and environmental factors. The purpose of this study is to test some hypotheses concerning the association of environmental factors with CNS defects. This first report gives a description of the material, with information on incidence, seasonal and yearly variations, sex distribution, and parental age. Subsequent reports will deal more specifically with various maternal and exogenous factors associated with CNS defects. Material and methodsThis epidemiological study is based on material from the Finnish Register of Congenital Malformations. Reporting of all congenital malformations detected during the first year of life was made compulsory in Finland in 1963, the year in which the register was founded. The group of CNS defects is one of the 'detector' defects, for which extensive information is collected through the maternity welfare centres. The control for each case is the mother whose delivery preceded that of the study mother in the same maternity welfare district. The information on both the study and the control cases is collected by interviews with the mothers and from the records of the welfare centres obtained during pregnancy. Thus the information is prospective as well as retrospective. Full details of the organisation of the register have been published elsewhere (Sax6n et al., 1974

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“…The cause of anencephaly is unknown but its distribution throughout the world varies with race and social class from a nadir of 0-2 per 1000 deliveries in Norway to a zenith of 4-8 per 1000 births in Belfast and Dublin (Lemire, Beckwith & Warkany, 1978). The incidence in the Edinburgh area of Scotland is 2-8 per 1000 deliveries (Elwood, 1970;Elwood & MacKenzie, 1971) and females are more commonly affected than males such that in Edinburgh the percentage of anencephalic males is close to the 30% of total affected births reported by MacMahon & McKeown (1952).…”

Section: Introductionmentioning

confidence: 99%