Tendências seculares das proporções de nascimentos entre gêneros na América do Sul durante a segunda metade do século XX / Secular trends in sex ratios at birth in South America over the second half of the 20th century

OBJETIVOS: Analisar as tendências seculares e gradientes de latitude na proporção masculino-feminina ao nascimento (M/F: masculinos divididos por total de nascidos vivos) no Continente Sul Americano. MÉTODOS: Os dados sobre nascidos vivos masculinos e femininos em âmbito nacional, durante um ano por país, foram obtidos da Organização Mundial da Saúde e analisados com tabelas de contingência. O continente foi arbitrariamente dividido em duas regiões: a primeira: de 10º acima da linha do Equador até 20º abaixo da linha Equador (10º N-20º S), e uma segunda abaixo de 20º da linha do Equador (> 20ºS). RESULTADOS: O estudo analisou 147.773.689 nascidos vivos. Encontrou-se uma tendência crescente M/F na maioria dos países próximos ao Equador (10º N-20º S) (p = 0,004). A análise do período entre 1950 e 1974 não mostrou diferença, porém após este período (1974-1996) encontrou-se um aumento M/F (p = 0,03). Um aumento na proporção M/F foi encontrado em todo o período na região > 20ºS (p < 0,0001). Também foi observado um gradiente de latitude, nascendo mais lactentes masculinos em latitudes mais frias (mais ao sul, > 20ºS) (p < 0,0001). CONCLUSÃO: A proporção M/F está crescendo na América do Sul, diferentemente do presente declínio na Europa e na América do Norte. Este estudo também mostra que os gradientes de latitude para a proporção M/F são semelhantes àqueles anteriormente publicados na América do Norte, nascendo mais bebês masculinos nas latitudes mais frias, ao contrário das tendências publicadas na Europa. É provável o inter-relacionamento de vários fatores ainda pouco entendidos.

OBJECTIVES: Latitude gradients have been found in the male-female ratio at birth (M/F: male divided by total births), which is anticipated to be 0.515. METHODS: Annual national male and female live births by country were obtained from the World Health Organization (WHO) and analysed with contingency tables. The continent was arbitrarily divided into two regions: a region 10º above the Equator to 20º below the Equator, and a second area 20º below the Equator. RESULTS: This study analyzed 147,773,689 live births. An overall increasing trend in M/F was found for the region >20º (p < 0.0001) for the entire period. For the aggregate, a significant decrease was present for the period 1950-74 (p = 0.01) followed by a significant increase thereafter (p < 0.001). A latitude gradient was also noted, with more males being born in cooler (more Southern > 20º S) latitudes (p < 0.0001). There were 3,765,648 male births in excess of what was anticipated. CONCLUSION: The M/F ratio is increasing in South America, unlike the decline present in Europe and North America. This study also showed that M/F latitude gradients are similar to those previously reported in North America, with more males being born in cooler latitudes, contrary to the trends reported in Europe. The interplay of several poorly understood factors is likely.

Increasing age at diagnosis of celiac disease in Malta.

OBJECTIVE: Recent studies have shown that celiac disease is being diagnosed at a progressively later age. This paper analyses trends in age at diagnosis in a closed island population. METHODS: Patient case notes of all known patients with celiac disease were retrieved and demographic information, mode of presentation including symptomatology and diagnostic criteria were obtained. Over the period 1985 to 2000, information was available on 42 patients with celiac disease. All were aged 14 years. RESULT: The mean age at diagnosis showed an increasing age, with a constant disease incidence. A highly significant positive correlation was found for age at diagnosis with time (rho=0.4, p=0.009). CONCLUSION: It is thought that breast feeding, with later introduction of gluten containing products in the diet, leads to a later presentation of celiac disease. In Malta, over the period under study, the breast feeding rate rose from 20% to 60%. Our findings support the hypothesis that breast feeding offers a degree of protection against the early development of celiac disease, without actually reducing the incidence of the disease.

Type 2 cryoglobulinemia treated with plasmapheresis associated with IgA nephropathy.

Cryoglobulinemia is caused by antibodies which precipitate in blood on exposure to cold, and redissolve on warming. The authors present a child with essential, Type 2 cryoglobulinaemia, successfully treated with plasmapheresis, who developed glomerulonephritis due to IgA nephropathy. Conservative treatment resulted in spontaneous improvement with no deterioration in renal function.