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Biology or behaviour? HIV reduces the fertility of African women

Sub-Saharan Africa (SSA) has been hardest hit by the AIDS pandemic. As the tragedy unfolds, there is growing evidence that HIV affects fertility and may influence fertility change across the sub-region. But what are the mechanisms underlying these changes and how should data be used to calculate more accurately the effect of HIV on fertility?

A joint study by the London School of Hygiene and Tropical Medicine and Oxford University (UK) found that fertility is reduced in HIV-positive women for both biological and behavioural reasons, and that antenatal surveys may underestimate HIV prevalence in women.

Fertility and HIV prevalence are both influenced by a range of biological and behavioural factors affecting sexual relations. These factors are particularly important for women with HIV. Using statistics from across SSA, the study calculated fertility in HIV-positive and negative populations, as well as HIV prevalence in pregnant and non-pregnant women. The researchers estimated the extent of fertility reduction in HIV positive women, and the effect on the fertility of the general population. Their results showed that:

The fertility of HIV positive women is 25 - 40% lower than HIV negative women in all but the youngest age group; older women have particularly reduced fertility.
In regions of high HIV prevalence, the relatively low fertility of HIV-positive women will result in a decline in fertility in the general population.

In populations where contraceptive use is low, these results can be explained by both biological and behavioural factors:

HIV-positive women have lower fertility as a result of foetal loss due to infections, co-infection with other sexually transmitted infections, and changes to their menstrual cycle.
Knowing of their infection, HIV positive women are more likely to use contraception. Anxiety about the fate of existing children means women are unwilling to have more children who could be orphaned.

HIV particularly affects the health and fertility of young adults, leaving countless orphaned children, and exacerbating the socio-economic problems faced by many SSA countries. The study has important implications for family planning and the measurement of HIV prevalence:

Family planning programmes should promote condoms and target their services at neglected groups such as teenagers.
Counselling on HIV prevention methods should be available for those most at risk due to their own or their partners’ sexual activities.
Antenatal surveys provide over 70% of HIV prevalence estimates for women. However, these will underestimate the true rate because women with HIV are less likely to be pregnant. This bias should be quantified and used to produce correct prevalence estimates.

Source(s):
‘Measuring the impact of HIV on fertility in Africa’ by B. Zaba and S. Gregson AIDS 12 Suppl 1 (1998)
'Adjusting HIV prevalence data collected in ante-natal clinics to obtain estimates for the general female population' by B. Zaba et al., AIDS 14 (2000)

Funded by: UK Department for International Development (HPD)

id21 Research Highlight: 24 January 2001

Further Information:
Basia Zaba
Centre for Population Studies
London School of Hygiene and Tropical Medicine
49-51 Bedford Square
London
WC1B 3DP
UK

Tel: +44 (0) 20 7636 8636
Fax: +44 (0) 20 7436 4230
Contact the contributor: basia.zaba@lshtm.ac.uk

London School of Hygiene and Tropical Medicine, UK

Simon Gregson
Wellcome Trust Centre for the Epidemiology of Infectious Disease
Department of Zoology
University of Oxford
South Parks Road
Oxford
OX1 3DF
UK

Tel: +44 (0) 1865 281 886
Fax: +44 (0) 1865 281 245
Contact the contributor: Sajgregson@aol.com

Wellcome Trust Centre for the Epidemiology of Infectious Diseases

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