Supplement Figure 5 Median estimates of reported age at marriage by 5-year birth cohort for (A) men and (B) women. IQR, interquartile range. Data include all reports after corrections and estimations for inconsistent reports. The IQR and median age at marriage could not be calculated for men born after 1975 as only 20% of men in this birth cohort are (or had been) married. The upper value of the IQR could not be calculated for women born after 1975 as 52% of women in this birth cohort are (or had been) married. Men marry at significantly older ages than women (log-rank test x2 = 5647, p,0.001; fig 4). A stable age at marriage among men and women is also illustrated by plotting the median age for each birth cohort (fig 5). The reports from those reporting in at least two surveys were then combined and analysed in a life table format. Men generally reported an increased age at marriage as they aged, particularly those in the youngest birth cohort (reading across the table; table 4). Women in older birth cohorts (1955–9 and before 1955) reported decreasing ages at marriage as they aged. However, for women in younger birth cohorts (1965–9 to after 1975), the reported age at marriage increased as they aged. Time spent single after sexual debut The average number of person-years spent between first sex and marriage has remained constant for men and women (fig 6). The mean (SD) duration of time spent single after sexual debut is much longer for men than for women (4.1 (4.1) years vs 0.3 (1.6) years). A greater proportion of women than men indicated i38 Figure 6 Distribution of person-years spent as a virgin, sexually active and unmarried and married between the ages of 10 and 25 years for men and women. that their first sexual experience was within marriage; 69.8% (6748/9666) and 15.3% (729/4760) of married women and men, respectively, reported age at first sex to coincide with age at marriage. DISCUSSION Including reports of age at first sex and age at marriage identified as unreliable in survival analyses did not alter our results, suggesting that much of the unreliability may be attributable to random misreporting rather than systematic biases such as social desirability bias. This absence of alteration of trends indicates that the observed trends can be interpreted with some confidence, despite the high levels of misreporting. Furthermore, this provides some reassurance when interpreting trends in serial cross-sectional data, such as from Demographic and Health Surveys (DHS) where such inconsistencies cannot be identified. However, consistency of reporting does not always signify accuracy; an individual may consistently report an incorrect age at first sex, a bias which cannot be detected. In this rural Zimbabwean population, women initiate sex and enter marriage at younger ages than men but spend much less time between first sex and marriage. Comparisons across all surveys by birth cohorts which span a period of .40 years indicate that the median age at first sex has remained constant over time among women but has declined gradually among men. Median age at marriage has remained relatively stable for both men and women. However, tracing birth cohorts between surveys revealed reporting biases. It is possible that some individuals (particularly young people) deliberately report an older age at first sex due to exposure to HIV prevention campaigns promoting delaying age at first sex and abstinence, in addition to the pressure of other social norms. With respect to Sex Transm Infect 2009;85(Suppl I):i34–i40. doi:10.1136/sti.2008.033431