The researchers, from the National University of Singapore, conducted a study that evaluated the extent of contraceptive use among women aged 15 to 49. They analyzed previous data over the past two decades related to contraceptive use from over 194 countries.
They found that from 1990 to 2010 the use of contraception increased from 55 percent to 63 percent in women aged 15 to 49, at the same time the unmet need for it dropped by 3 percent (from 15 percent to 12 percent).
Global demand for contraception is expected to increase from around 900 million in 2010 to 962 million in 2015. This is mainly due to population growth.
The largest increase in the use of contraception use was in southern Asia and eastern, northern and central Africa. However, in two regions of Africa contraception prevalence remained low, in 2010 less than 20 percent of married women in this region used contraception.
146 million married women didn't have a means of contraception in 2010 - in central, eastern and western Africa up to 20% of women had no access to contraception.
The researchers also estimated the prevalence of women using modern means of contraception (hormonal contraception). Over the last twenty years they found that there has been a considerable increase in the prevalence of contraception using modern methods.
According to a survey conducted by the National Center for Health Statistics (part of the Centers for Disease Control and Prevention), the most common types of contraception among American women aged 15 to 44 are birth control pills and female sterilization.
Co-author, Dr Ann Biddlecom, Fertility and Family Planning Section Chief at the United Nations Population Division, wrote:
"Our model-based annual estimates and projections of family planning indicators and the degree of uncertainty around them provide the global health and development community with a better understanding of the progress made, the likely path ahead, and the payoffs that can be accrued by investment in family planning now."
Dr Leontine Alkema, Department of Statistics and Applied Probability and the Saw Swee Hock School of Public Health, National University of Singapore, said:
"Model-based estimates are required for better monitoring of trends in family planning indicators, and for global health indicators in general, when there are significant problems with data availability or quality.
Attempting to evaluate trends in such instances is comparable to trying to monitor and project the stock market when stocks are updated on a random schedule with all the prices in different currencies. Statistical models, informed by experts in the field, are required to help to sort out what is really going on."
An Editorial published in The Lancet (September 2009) explained that addressing the issue and providing contraception to those who need it would also slow population growth and alleviate demographic pressure on the environment.
Written by Joseph Nordqvist