Trends by geographical latitude were also analysed. The null hypothesis was that there were no significant geographical

or temporal differences in M/F. Annual male and female live births had been obtained directly from WHO in 2000. The original sources were contacted (Drs. Galea and Inoue – personal communication) and the data was made available as an official, comma-delimited file directly LY2109761 from WHO. This was imported into Microsoft Excel, which was then used for collation and analysis. Data was available for South American countries as shown in Table 1. Data for Guyana and French Guiana were unavailable. South America may be divided into an area that spans from Honduras at circa 10° above the equator to 20° below the Equator, and a second area 20° below the Equator

and further south ( Table 1). Thus, only small parts of Bolivia and Brazil extend south and only small parts of Chile and Paraguay extend north of this arbitrary division. Excel was used for data entry, overall analysis, Pearson correlations and charting. The quadratic equations of Fleiss were used for exact calculation of 95% confidence intervals for ratios.6 Chi-squared Regorafenib ic50 tests and chi-squared tests for trends for male and female births were used throughout. The latter were applied using the Bio-Med-Stat Excel add-in for contingency tables. This add-in is based on the original work on this subject which led to the development of the Cochran-Armitage test (Dr.

Peter Slezák, Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, personal communication). A p-value ≤ 0.05 was considered significant. This study analysed 147,773,689 live births. There have been significant increases and also decreases in M/F in different countries (Table 1). Significant trends were present mostly in countries closer to the equator. No discernable pattern was noted in that trends were sometimes opposed in neighboring countries. Countries were grouped as described in Table 1 (above and below 20° latitude), and five-year trends for live births are shown in Table 2. For the region 10° N-20° S (top part of table) data was available for some (but not all countries) up to 1995, and hence, the absolute values for male, female and total births are smaller for the last 3 columns for this Erastin mw region in Table 2. For the region >20° S, data was only available for some countries (not all) up to 1996. Hence, the last two columns are blank and for the last column with data, the male, female and total births are smaller for the last column for this region in Table 2. An increasing trend in M/F was found for the region >20° (r=0.3, chi=24, p<0.0001) for the entire period. Overall, for the aggregate (the entire continent), a significant decrease was present for the period 1950-74 (r=-0.3, chi=5.9, p=0.01) followed by a significant increase thereafter (r=0.5, chi=60, p<0.001).