More boys as globe warms up

BOYS ARE more likely to be conceived after a hot spell, while a cold snap favours girls, according to a study based on 50 years of birth records.

Parents wanting to choose the sex of their child should consult the thermometer, according to Alexander Lerchl, a German scientist who has highlighted a link between the mercury rising and the number of boys. The sex bias is small but could have important consequences if global warming further increases the ratio of males to females, he writes in New Scientist magazine.

Mr Lerchl studied average monthly temperatures in Germany between 1946 and 1995, looking for months that were either very hot or very cold - then compared them with sex ratios in German birth records over the same period. The crucial time was a month before conception, he discovered, and deviations of just a few degrees centigrade had an impact.