Background

Natsal-1 was carried out in response to an urgent need for information about sexual practices in the context of the HIV/AIDS epidemic. The survey provided much needed data to predict and prevent HIV transmission in Britain. The first survey was the focus of much media attention having been refused public funding at the direction of the then Prime Minister, Margaret Thatcher. Fortunately the Wellcome Trust stepped in to fund the project.

The data were used more widely than had been anticipated, by academics and practitioners in the fields of sexual health epidemiology, policy and practice. However, towards the end of the 1990s, new data were needed to investigate changes in sexual behaviour and to respond to demand for up-to-date information on sexual health and behaviour. In response to this demand, Natsal-2 was carried out in 2000. Where Natsal-1 had surveyed a probability sample of 18,876 adults aged 16-59 in 1990, the sample for Natsal-2 was truncated to 12,110 adults aged 16-44 years, for reasons of cost-effectiveness.

The aims of Natsal-2 were broader and went beyond a concern to provide data in the context of HIV/AIDS. The survey aimed to:

  • provide a detailed understanding of patterns of sexual behaviour in Britain
  • provide data for HIV/AIDS projections in Britain
  • assess whether there had been changes in sexual behaviour since Natsal-1; and
  • measure the prevalence of Chlamydia trachomatis infection, via the collection and analysis of urine samples

Further information on Natsal-1 and Natsal-2 can be found here.

Ten years after Natsal-2, the research team was successful in winning funds to carry out Natsal-3, which will provide new data. Natsal-3, a survey of 15,000 adults aged 16-74 years, is currently underway. Natsal-3 differs from Natsal-2 in a number of ways. Firstly, the sample includes older people, aged up to 74 years. Secondly, the aims of Natsal-3 relate to a broader definition of sexual health, and one which includes not only behaviour and experiences relating to pregnancy and sexually transmitted infections, but also sexual function and enjoyment. Thirdly the survey incorporates more biological sampling and testing. Further, the scope of Natsal-3 includes more substantial methodological development work. And finally, the study now comprises not only a quantitative component, the main survey, but a qualitative component using in-depth interviews with selected individuals to amplify and augment the survey findings. As a result, Natsal-3 adds to the objectives of Natsal-2 and aims:

  • To advance sexual behaviour research methodology, particularly data collection methods, the validation of behavioural measures (for example, sexual function) and biological measures (for example sexually transmitted infections (STIs) and hormones).
  • To analyse the data generated from the survey to:
    • provide estimates of variability in sexual partnership patterns, sexual activity, function and satisfaction in the population and demographic sub-groups;
    • provide self-reported estimates of a range of sexual and reproductive health outcomes (including pregnancy, STI diagnosis, contraception use) and health service use;
    • explore the variation in sexual behaviour and function over the life course, specifically by including an older age-group;
    • describe changes in sexual activity over time and trends in relationships, reproductive history and patterns of fertility using Natsal 1990, 2000 and 2010;
    • estimate the prevalence and correlates of N.gonorrhoeae, type-specific HPV, HIV antibody and M.genitalium, in addition to C.trachomatis;
    • measure the gender-specific distribution of salivary testosterone and its relationship to sexual behaviour, function, and ageing, and explore interactions between physiological and social influences on behaviour;
  • To explore the meanings and significance of particular experiences for individuals and, where relevant, their motivations to engage in them.
  • To triangulate the Natsal data with other data sources to:
    • use the measured distribution of key STI risk behaviours to inform estimates of HIV prevalence from surveillance data and for mathematical modelling of STI/HIV transmission dynamics;
    • contextualise convenience survey data (e.g. men who have sex with men, clinic populations);
    • evaluate strategies for improving sexual health.