The study, published Online First in The Lancet, was undertaken by researchers based at the United Nations Population Division in the Department of Economic and Social Affairs, and the National University of Singapore, and produced estimates of contraceptive prevalence (the proportion of women using contraception) and unmet need for contraceptives (the proportion of women who would like to delay or stop childbearing but who are not using any method of contraception to prevent pregnancy) in 194 countries worldwide between 1990 and 2010. The researchers used available data on contraceptive prevalence and unmet need for family planning, and where relevant data on unmet need were not available, they modelled the relationship between contraceptive prevalence and unmet need and used information from other countries in the region.
The results show that global contraceptive prevalence in married women of reproductive age has increased from 55% in 1990 to 63% in 2010, and unmet need for family planning has decreased from 15% in 1990, to 12% in 2010. However, because of population growth and an increased global awareness of and demand for modern family planning methods among women and couples, total demand for contraception is projected to grow worldwide from 900 million in 2010, to 962 million in 2015. Increased investment in family planning will be required to meet the needs of the 233 million women projected to have an unmet need for modern methods by 2015, say the authors.
The largest absolute increases in contraceptive prevalence (more than 15 percentage points) between 1990 and 2010 were in southern Asia and three sub-regions of Africa (eastern, northern, and southern Africa). However, in two sub-regions of Africa, contraceptive prevalence still remained low: by 2010, fewer than one in five married women used any contraceptive method in central and western Africa.
Between 1990 and 2010, the reduction in unmet need for contraception was greatest in central America and northern Africa, where it fell by 9 percentage points. Most countries experienced either stable rates of unmet need, or a reduction, yet more than 20% of married women in eastern, central, and western Africa were estimated to still have an unmet need for family planning in 2010. Worldwide, 146 million married women of reproductive age are estimated to have an unmet need for family planning in 2010, a figure which increases to 221 million if women using traditional contraceptive methods are included.
The researchers estimated how many women were using modern methods of contraception, such as hormonal contraception, compared to traditional methods such as periodic abstinence or withdrawal. They found that the rise in contraceptive prevalence in the last 20 years was largely attributable to an increase in the uptake of modern contraceptive methods, with around nine out of ten women worldwide estimated to use modern contraceptive methods in 2010.
According to author Dr Ann Biddlecom, Fertility and Family Planning Section Chief at the United Nations Population Division, "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."
Unmarried women who are sexually active were not included in this study, but the researchers hope that an extended version of the current statistical model will provide better estimates of contraceptive prevalence and unmet need in this population in future.
According to author Dr Leontine Alkema, Department of Statistics and Applied Probability and the Saw Swee Hock School of Public Health, National University of Singapore, "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."*
According to Professor John Cleland of the London School of Hygiene & Tropical Medicine, author of a Comment linked to the Article, "It is of concern that contraceptive use remains very low in many African countries. The Sahelian countries of Chad, Mali, Mauritania, and Mali are likely to experience a trebling of population size by mid-century which will present an impossible burden on their fragile ecosystems. Expansion of community-based services is a priority but of equal importance is the need to address social opposition to contraception by mass media and efforts to engage the support of religious and local leaders."*