sex-ratio

Conventionally defined as the number of males per 1,000 females in the population of a society. More boys than girls are born each year, but the excess number of males at birth is gradually reduced by the higher male mortality rate , to an age-point where the number of women begins to exceed the number of men. In most countries, the overall sex-ratio is below 1,000, with women outnumbering men. However, since the Second World War the sex-ratio has been rising in many Western industrial societies, so that the excess of females is now confined to older age-groups. In Britain, for example, the cross-over point rose from age 25 in 1901-10 to age 47 in 1930-2 and to age 57 years in 1980-2. Due to improvements in health care, and the (relative) absence of wars, men now outnumber women for most of their lives in many countries. Other factors affecting the sex-ratio are sex-selective migration patterns, and the female infanticide practised in countries where females are treated as socially inferior.

The sex-ratio is regarded as an important social indicator. It affects marriage rates, women's labour-market participation rates, and (it has been argued) sex roles.