0001 [Table 3]). The male births in excess of that which would be anticipated based on an M/F of 0.515 were calculated (using simple proportion) at 3,765,648 (Table 3). Studies that analysed data prior to 1950 observed generally increasing trends in M/F. For example, it was demonstrated selleck screening library that M/F was rising in Scandinavia before 1950, and decreased thereafter.7 This was notably true in Finland, with a rise in M/F from 1751 to 1948, and in Denmark.8 and 9 A declining M/F has been observed in many industrialized countries since

1950, since the more fragile male fetus may be spontaneously aborted at a higher rate than the more robust female fetus when exposed to hypothetical deleterious environmental factors.10 Adverse environmental factors or traumatic experiences that affect entire populations have both been shown to lower M/F. For example, M/F declines after warfare,11 earthquakes,12 and a multiplicity of environmental check details disasters.13 It appears that such events promote stressed pregnant women

to spontaneously abort male fetuses to a greater extent than female fetuses.14 M/F has been proposed as a potential surrogate sentinel health indicator.15 Despite these adverse factors, males are invariably born in excess of females,16 implying an even higher conception rate of males. A study in Europe has shown a higher incidence of male births in southern Europe, which is warmer, than in northern Europe.4 However, a study over a longer time

span that also incorporated the North American continent not only did not confirm the European trend, but also demonstrated that more males are born in the higher and cooler latitudes of the Northern American continent than in the southern parts of Tolmetin that continent.2 The South American data presented in this study is in accordance with the latitude gradient described in North America, and contrary to the latitude gradient observed in Europe.2 Moreover, in contrast with North America and Europe, M/F is increasing in South America.5 A simple calculation shows that, for the available years, there was a male birth rate in excess of the anticipated M/F of 0.515, resulting in a female birth deficit of at least 3,765,648. Various hypotheses have been elaborated to explain observed trends in M/F but with the available data, it is not possible to ascertain what factor/s have contributed to these findings These include, on the one hand, differing secular trends in M/F when comparing Europe and North America with South America, and on the other hand, latitude gradient differences in M/F that are in agreement in the Americas but display an opposite trend in Europe. Several poorly understood factors may be interacting. The author declares no conflicts of interest. Dr. Mie Inoue and Dr. Gauden Galea from the World Health Organization. “
“Rotaviruses are among the major causes of gastroenteritis affecting young children worldwide.