<P> Commonly, countries with gender imbalances have three characteristics in common . The first is a rapid decline in fertility, either because of preference for smaller families or to comply with their nation's population control measures . Second, there is pressure for women to give birth to sons, often because of cultural preferences for male heirs . Third, families have widespread access to technology to selectively abort female fetuses . </P> <P> As a contributing measure to gender imbalance in developing countries, Kristof and WuDunn's best estimate is that a girl in India, from 1 to 5 years of age, dies from discrimination every four minutes (132,000 deaths per year); that 39,000 girls in China die annually, within the first year of life, because parents did not give girls the same medical care and attention that boys received . The authors describe similar gender discrimination and gendercide in Congo, Kenya, Pakistan, Iraq, Bahrain, Thailand and many other developing countries . </P> <P> Some of the factors suggested as causes of the gender imbalance are warfare (excess of females, notably in the wake of WWI in western Europe, and WWII, particularly in the Soviet Union); sex - selective abortion and infanticide (excess of males, notably in China as a result of the one - child policy, or in India); and large - scale migration, such as that by male labourers unable to bring their families with them (as in Qatar and other Gulf countries). Gender imbalance may result in the threat of social unrest, especially in the case of an excess of low - status young males unable to find spouses, and being recruited into the service of militaristic political factions . Economic factors such as male - majority industries and activities like the petrochemical, agriculture, engineering, military, and technology also have created a male gender imbalance in some areas dependent on one of these industries . Conversely, the entertainment, banking, tourism, fashion, and service industries may have resulted in a female - majority gender imbalance in some areas dependent on them . </P> <P> One study found that the male - to - female sex ratio in the German state of Bavaria fell as low as 0.60 after the end of World War II for the most severely affected age cohort (those between 21 and 23 years old in 1946). This same study found that out - of - wedlock births spiked from approximately 10--15% during the inter-war years up to 22% at the end of the war . This increase in out - of - wedlock births was attributed to a change in the marriage market caused by the decline in the sex ratio . </P>

How many females and males are in the world