Experience from 83 countries shows that a 15% increase in contraceptive availability decreases fertility by nearly one child per woman. Birth rates have fallen two to seven times faster in lower-income countries with effective family planning programmes than they did in Europe and North America during a similar transition from high to low fertility. The rate of contraceptive use in developing countries rose from 40% in 1980 to 49% in 1990. At present, 15% of people in lower income countries use natural and barrier methods, as against 50% in upper-income countries.
Another source estimates that access by fertile couples to contraception has grown from under 10% three decades ago to more than 55% currently, in the developing world. This has helped reduce the historical average of 6 children per family (in virtually all societies) to about 3.8 in the developing world. Still, United Nations estimates put the number of women who want fewer children but have no access to family planning at 500 million.