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

Abstract

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.

Risk Factors of Anencephaly: A Case–Control Study in Dessie Town, North East Ethiopia

“…In the current investigation, maternal age between 26 and 30 years was significantly associated with the occurrence of anencephaly, although previous studies, by Aguiar et al and Barry Borman et al, reported no association between anencephaly and maternal age. 33,34 The observed higher incidence of anencephaly in mothers aged between 26 and 30 is comparable to that reported by Berihu et al for mothers in all age ranges. 15 Nevertheless, the relatively high incidence of anencephaly observed in this study in mothers in the age group of 20-30 years is interesting and deserves further investigation.…”

“…9,23 In the present study, spina bifida was also significantly associated with anencephaly (p<0.0001). The simultaneous presence of anencephaly and spina bifida appears to be due to a common structural abnormality of the neural tube, as suggested by Barry Borman et al 34 Although not statistically significant, polyhydramnios and oligohydramnios were also detected with anencephaly.…”

Maternal age is highly associated with non‐chromosomal congenital anomalies: Analysis of a population‐based case‐control database

“…The literature is not consistent on the age effect. Most studies have suggested a ‘U‐shaped’ association between maternal age and the relative frequency of NTDs 27,28 . Other groups suggest that a higher risk of NTD is likely associated with increased maternal age 29 .…”

Estudio epidemiológico sobre defectos de cierre del tubo neural. Detección del polimorfismo C677T en pacientes con mielomeningocele, del Hospital de Pediatría Juan P. Garrahan, sus madres y población general, entre los años 1999 y 2001

“…En áreas de riesgo elevado para anomalías congénitas, las mismas presentan patrones de distribución en forma de "U" o de "J" con máximos riesgos en madres jóvenes y/o madres de edad avanzada (275). En áreas de bajo riesgo, en cambio no se observan dichos patrones (50).…”

“…• HOMOCIGOSIDAD PARA LA FORMA MUTANTE DE LA ENZIMA MTHFR Para el estudio molecular (amplificación por PCR y digestión con enzimas de restricción), cada grupo (100 individuos) estuvo constituído por 50 hijos con sus respectivas madres (50). Este diseño de los grupos es similar al de otros trabajos sobre el tema (140) (288) (466) (499) y obedece al hecho que lo que se intenta evaluar es la interacción del binomio "madre-hijo" (factor ambiental y factor genético).…”