Reduced male births in major Italian cities

The downward trend in the sex ratio at birth that has occurred in several c ountries over the last 30 years was postulated to signal a deterioration in environmental conditions, particularly unfavourable for male conception an d fetus survival, In Italy, in contrast, an upward trend has been observed. Assuming that exposure to reproductive hazards occurs mainly in the major cities, we contrasted the 1970-1995 sex ratio trend for the metropolitan ar ea (defined as the four provinces containing the largest Italian cities) wi th that for the non-metropolitan area (defined as the rest of the country). In the metropolitan area, the proportion of live-born males showed a negat ive trend significantly different from the positive trend observed in the r est of the country. Moreover, the stillbirth rate among males was constantl y and significantly higher in the metropolitan area. Our results suggest th at the decrease in the sex ratio at birth observed in the metropolitan area might be interpreted as a signal of increasing exposure to hazardous envir onmental conditions for male conceptions and neonates.