The world health report

Chapter 4

Sexual and reproductive health

Risk factors in the area of sexual and reproductive health can affect well-being in a number of ways (see Table 4.4). The largest risk by far is that posed by unsafe sex leading to infection with HIV/AIDS. Other potentially deleterious outcomes, such as other sexually transmitted infections, unwanted pregnancy or the psychological consequences of sexual violence are considered elsewhere in this report (see Figure 4.5).

Unsafe sex

HIV/AIDS is the fourth biggest cause of mortality in the world. Currently, 28 million (70%) of the 40 million people with HIV infection are concentrated in Africa, but epidemics elsewhere in the world are growing rapidly. The rate of development of new cases is highest in Eastern Europe and central Asia (23). Life expectancy at birth in sub-Saharan Africa is currently estimated at 47 years; without AIDS it is estimated that it would be around 62 years (23). The consequences of HIV/AIDS extend beyond mortality; children are orphaned and entire economies can be affected.

Most people infected with HIV do not know they are infected, making prevention and control more difficult. Various sexual practices contribute to the risk of sexually transmitted infections. They increase the risk of exposure to pathogens ("high risk sex") and the chance of being infected by the pathogens, given high risk sex. The spread of a sexually transmitted disease is also affected by the duration of infectiousness, which depends on treatment availability and effectiveness. Aspects of high risk sex include the number of sexual partners, the rate of change of sexual partners, who the sexual partners are, and the type of sex acts involved.

Sexual behaviour is difficult to measure, and estimates of the prevalence of high risk behaviour rely on self reports, where sampling is usually of individuals (rather than partnerships) and often excludes high risk individuals. Most of the infections prevalent in 2001 were acquired through heterosexual sex. This analysis estimates the burden of disease from unsafe sex between men and women, because epidemics driven by heterosexual contact are responsible for the most demographically significant consequences. No single measure of "unsafe sex" has been used, because sex is only unsafe with respect to the context in which it occurs. Therefore patterns of sexual behaviour have been described.

The prevalence of different sexual behaviours and characteristics varies greatly between countries and between regions. Current estimates suggest that more than 99% of the HIV infections prevalent in Africa in 2001 are attributable to unsafe sex. In the rest of the world, the 2001 estimates for the proportion of HIV/AIDS deaths attributable to unsafe sex range from about one-quarter in EUR-C to more than 90% in WPR-A.

Globally, about 2.9 million deaths (5.2% of total) and 91.9 million DALYs (6.3% of all) are attributable to unsafe sex. The vast majority of this burden results from HIV/AIDS occurring in the African region. About 59% of total unsafe sex disease burden occurs in AFR-E and about 15% in both AFR-D and SEAR-D. In addition, the African countries are unique in suffering more attributable burden in women than in men, as a result of unsafe sex.

Lack of contraception

The cause of unintended pregnancy is non-use, or ineffective use, of contraception. Contraceptive use can be categorized into modern methods (such as the oral contraceptive pill, barrier methods, the intrauterine device or sterilization), traditional methods (such as the rhythm method), and no method. Modern methods have the lowest probability of unintended pregnancy. The overall rates of contraceptive use, the effectiveness of the different methods, and the mix of methods used in a country will determine the risk of unintended pregnancy and its consequences.

Demographic health surveys indicate that the proportion of women aged from 15 to 29 years who currently use a modern method of contraception varies from 8% to 62% in the different subregions, and the prevalence of traditional methods ranges from 3% to 18%. If all women of this age group who want to either space or limit future pregnancies were using modern methods of contraception (the counterfactual distribution), then the prevalence of use would range from 43% to 85%. For these analyses it was assumed that there was full access to modern contraception for women in the AMR-A, EUR-A and WPR-A subregions. For most other regions, the difference between current levels and full access is approximately 35%. The use of modern methods is somewhat higher among women aged from 30 to 44 years. This group also has a higher proportion of women who wish to space or limit future pregnancies, so the differences between the current and counterfactual prevalences are similar to those in the younger age group.

Unintended pregnancy leads to unwanted and mistimed births, which have maternal and perinatal complications in the same way as wanted births. Similarly, stillbirths and miscarriages occur as pregnancy outcomes with some risk to the mother, irrespective of whether the pregnancy was intended or not. The likelihood of an abortion following an unintended pregnancy depends on whether the pregnancy is mistimed (that is, the woman wanted to get pregnant, but not within the next two years) or unwanted (that is, the woman did not want to conceive or did not want any more pregnancies). The risk of abortion-related complications is proportional to the risk of unsafe abortion, which is strongly related to the legality of abortion in the country concerned.

Worldwide, unplanned pregnancies were responsible for about 90% of unwanted births, the remainder being due to method failure. This amounted to 17% of maternal disease burden and 89% of unsafe abortions. Attributable fractions for maternal disease were highest in AMR-B, AMR-D, EUR-B and SEAR-D, ranging from 23% to 33%. The attributable fractions in these subregions for unsafe abortions were also the highest and ranged from 85% to 95%.

Throughout the world, lack of contraception caused about 149 000 (0.3%) deaths and 8.8 million (0.6%) DALYs. Africa, South-East Asia, AMR-D and EMR-D had the highest disease burden attributable to lack of contraception, ranging from 0.6% to 1.5% of deaths and 1.4% to 2.6% of DALYs in those subregions.