HIV prevalence among pregnant women
Women who are pregnant have by definition had unprotected sex sometime in the last ten months. Levels of HIV infection in these women do not reflect levels among women who are not having sex, among women who are infertile, or among women who are systematically using contraception, including barrier methods such as condoms which also prevent HIV transmission. Confining the indicator to women aged under 25 aims to give a picture of recent trends in infection. Most infections in this age group are relatively new, and data from these younger women are also less subject to bias than data for the whole reproductive age span. The indicator is reported for women aged 15-24. However it is strongly recommended that two separate figures be reported: one for women aged 15-24 and one for women across the whole reproductive age range of 15-49. Since many countries have in the past failed to report HIV prevalence broken down by age, it is important to continue to report a figure for HIV prevalence across 15-49-year-olds, to allow for the comparison of trends over time. Additional information may be gained by looking at HIV prevalence by parity of mother. Such information is often routinely collected in sentinel surveillance and analysis of trends among women of parity 0 and 1 combined is a good additional indicator of trends in HIV incidence among young women.
Number of blood samples taken from women aged 15-24 that test positive for HIV
Total number of blood samples taken from women aged 15-24
The data for this indicator are obtained from the national sentinel surveillance system for HIV, and the indicator is calculated through unlinked anonymous testing for HIV of blood samples taken from women at sentinel antenatal clinics chosen to reflect urban, rural, ethnic and other socio-geographic divisions in a country. Even where programmes exist that simultaneously offer counselling and voluntary HIV testing for pregnant women to reduce mother to child transmission, only the results of unlinked, anonymous screening of blood taken for other purposes should be used in calculating this indicator of HIV prevalence. Refusal and other participation bias are considerably reduced in unlinked anonymous HIV testing compared with other forms of testing.
Geographic location: N/A
Pregnancy status: N/A
Time period: N/A
Type of orphan: N/A
Vulnerability status: N/A
The indicator gives a fairly good idea of relatively recent trends in HIV infection nationwide in countries where the epidemic is heterosexually driven. It is less reliable as an indicator of overall epidemic trends in areas where the bulk of HIV infection remains confined to sub-populations with especially high-risk behaviours. Even in countries with generalised heterosexual epidemics, there are wide regional, ethnic or other differences in trends in HIV infection. These will be lost when data are aggregated into a single national figure. For programme purposes, prevalence should thus always be reported separately by site as well as by a single national figure. Care should be taken in reporting HIV prevalence estimates by sites, however, given the possible political sensitivity of results. In the past, sample sizes in regular sentinel surveillance have been selected in order to measure changing trends across the whole age range of 15-49. Numbers in each five-year age band may have been too small to yield any reliable trend data, particularly at individual sentinel sites. In order to construct a reliable indicator around the narrower age range, larger sample sizes in the younger age groups will be needed. Clearly, trends in HIV infection among pregnant women will not adequately reflect some of the most important changes in behaviour supported by AIDS prevention programmes abstinence and consistent condom use in all populations and not simply the antenatal care clients. Trends in HIV infection are beset by a number of biases, as described above. Prevalence among pregnant women gives an idea of trends in prevalence in the general population, but is not an accurate reflection of overall levels in all women, let alone in all men. Prevalence data should therefore be reported together with behavioural data (such as mean age at first sex or condom use at last sex) for better explanatory power.