East Ireland 1980-1994: epidemiology of neural tube defects

Abstract

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.

Neural Tube Defects in Algeria

“…Others had reported 0.73 (Daoud et al, 1996), 0.78 (Golalipour et al, 2007;Stevenson et al, 2000) and 0.85 (Samson, 2003), or even a male predominance 1.07 (Wasant & Sathienkijkanchai, 2005). The predominance of female anencephalic births over males in our study is similar to that seen in other countries and likewise the slight female predominance in spina bifida births (McDonnell et al, 1999).…”

“…The spina bifida to anencephalic ratio is similar to that reported by other workers (McDonnell et al, 1999). Our research was shown that more than half of mortality is a consequence of anencephaly (Eurocat Working Group, 1991).…”

“…Our research has shown that rate of NTD was higher in May with a peak in June. In Ireland the peak prevalence was in April (McDonnell et al, 1999) and in Northern Iran it was in December (Golalipour et al, 2007). The seasonal variations in the birth prevalence and the peak of NTD observed in our population were difficult to compare with those of previous studies, which were performed in countries where income, seasonal changes in diet is completely different.…”

Similar rhythms of seasonal conceptions in neural tube defects and schizophrenia: A hypothesis of oxidant stress and the photoperiod

“…One of us reviewed 20 such reports in 1986 (Fraser et al, 1986). Seven additional studies appeared thereafter (Stoll et al, 1988;Abrate et al, 1990;Angerpointner et al, 1990;Castilla et al, 1990;Wu et al, 1991;Bound et al, 1998;McDonnell et al, 1999). Figure 1 presents the results, based again on month of conception.…”

Prenatal Diagnosis of Open Spina Bifida in Emilia-Romagna

“…Among these, the myelomeningocele (protrusion of the nervous tissue and its covering through a defect in the vertebrae and skin) represents by far the most common type, accounting for about 90% of spina bifida cases [1,2]. Its incidence is reported to range from 2 to 20 per 10,000 births according to different geographic areas, being higher in the United Kingdom (from 5.9 to 13.1 per 10,000 births) and Asia (10.6 per 10,000 births) and lower in the United States (from 3.1 per 10,000 births) and in the other European countries (from 2.0 to 10.5 per 10,000 births) [3,4,5,6,7]. The causes of spina bifida are multifactorial, including genetic predisposition, environmental factors and maternal conditions [8].…”