Women are biologically, epidemiologically and socially more vulnerable. For example, women tend to marry or have sex with men older than themselves, who may have had more sexual partners and hence be more likely to have become infected. In some relationships or cultural environments, it is almost impossible for women to insist on protecting themselves against the virus, through mutual fidelity or condom use. In other cultures, men expect sex with any women receiving their financial support. As infections in women rise, so do infections in the infants born to them.
Perinatal transmission can occur during pregnancy, during delivery and through breast- feeding.
The extensive spread of HIV in South and Southeast Asia began in the mid-1980s, but its progression has been very rapid. What is happening in Africa now could be dwarfed by the Asian epidemic. While India and Thailand account or the majority of infections, rapid HIV spread into specific populations in other counties of the region has also been noted. For the region's adults, the predominant modes of transmission are unprotected heterosexual intercourse and needle sharing. The AIDS epidemic in Southern and Southeast Asia gained an early foothold among injecting drug users.