The inactivated purified hepatitis A vaccine that we tested is well tolerated, and a single dose is highly protective against clinically apparent hepatitis A.

Girls' school participation has expanded considerably in the developing world over the last few decades, a phenomenon expected to have substantial consequences for reproductive behaviour. Using Demographic and Health Survey data from 43 countries, this paper examines trends and differentials in the mean ages at three critical life-cycle events for young women: first sexual intercourse, first marriage, and first birth. We measure the extent to which trends in the timing of these events are driven either by the changing educational composition of populations or by changes in behaviour within education groups. Mean ages have risen over time in all regions for all three events, except age at first sex in Latin America and the Caribbean. Results from a decomposition exercise indicate that increases in educational attainment, rather than trends within education groups, are primarily responsible for the overall trends. Possible explanations for these findings are discussed. IntroductionA successful transition to adulthood includes adequate preparation for adult roles and the capacity to make informed decisions about the timing of key life events (Lloyd 2005). First sexual intercourse, first marriage, and first birth are among the most consequential of these events. Taking on the roles of sexual partner, spouse, and parent too early may undermine the success of this transition, jeopardize a young person's health and well-being, and have deleterious effects on the health and well-being of her offspring (Lloyd 2005). In lessdeveloped-country settings, where HIV is endemic and where young women suffer disproportionately from sexually transmitted infections (STIs), the earlier sex is initiated, the longer the exposure to the risk of infection. On average, the younger the age of a woman at marriage, the larger the age difference between spouses, the less agency women are reported to have within marriage, and the higher the likelihood of marital dissolution (Singh and Samara 1996;Mensch 2005). And finally, early childbirth, before achieving full physical maturity around age 16, is associated with a higher likelihood of maternal death (Blanc et al. 2013;Nove et al. 2014), infant death, and other poor child health outcomes (Finlay et al. 2011). Moreover, the timing of births has an effect on population growth. For all these reasons, there is considerable interest on the part of researchers and policymakers in trends that are the focus of this study: ages at first sex, marriage/union, and childbirth in the developing world.The paper begins with a review of the literature on the impact of women's schooling on fertility and on the timing of first sex, first marriage, and first birth. This is followed by a detailed empirical analysis of levels and trends in the ages at these life-cycle events, based on data collected by Demographic and Health Surveys (DHS) since 1986 in 43 less developed countries in Asia and Northern Africa, Latin America and the Caribbean, and sub-Saharan Africa. The mean ages at events are estimated with a meth...

The quality of drug data in the 1984 wave of the National Longitudinal Survey of Youth is explored. Comparisons with other national surveys indicate that underreporting of use of illicit drugs other than marijuana appears to have taken place, and that light users of these drugs are underrepresented among the self-acknowledged users. Comparison with marijuana use reported four years earlier indicates that experimental marijuana users are much less likely than extensive users to acknowledge involvement. Even after controlling for frequency of use, underreporting is more common among terminal high school dropouts and minorities. Not only individual characteristics but field conditions also contribute to underreporting. Familiarity with the interviewer, as measured by number of prior interviewing contacts, depresses drug use reporting. We speculate that interviewer familiarity increases salience of normative standards and that participants respond not only in terms of their past familiarity but also in terms of their subjective expectations regarding the probability of a future encounter with the interviewer.

The timing of first union merits investigation not only because of the close temporal link between marriage and the onset of childbearing, but also because the age when men and women marry has implications for the organization of family life and for gender relations within society. This paper begins by reviewing the contributions of various social science disciplines to an understanding of the timing of marriage. Using current status data from 73 countries provided by the United Nations Population Division and retrospective data from 52 Demographic and Health Surveys conducted between 1990 and 2001, we then examine recent trends in the timing of first marriage or union for men and women in the developing world. With the exception of South America for both sexes and South and Southeast Asia for men, substantial declines have occurred in the proportion of young men and women who are married. Given the differentials in the timing of marriage by educational attainment and residence, we assess whether the decline in the proportion of young people who are married is related to increases in schooling and urbanization. Expansion of schooling for women has had some impact, but a considerable portion of the reduction in early marriage is not explained by changes in levels of education. We consider other factors that might account for the increase in age at marriage. Finally, we review what is known about the consequences of changing age at marriage with a particular focus on risk of HIV infection.

Leaving school prematurely is often claimed to be among the most negative consequences of early marriage and pregnancy for girls in less developed countries. However, an analysis of the relative frequency with which these events actually occur or are named as reasons for leaving school reveals that, at least in the case of francophone Africa, they explain no more than 20 per cent of dropouts. To the extent that demographic events trump school or family factors as determinants of school-leaving, our data indicate that it is union formation--defined by the DHS as first marriage or cohabitation--rather than childbirth that is more likely to have this effect. 'Schoolgirl pregnancy' typically accounts for only between 5 and 10 per cent of girls' departures from school. Furthermore, the risks of leaving school because of pregnancy or marriage have declined over time with the decline in rates of early marriage and childbearing.

Objectives: To investigate in a district in Kenya the level and consistency of reporting of sexual behaviour among adolescent girls randomly assigned to two modes of survey interview: face to face interview and audio computer assisted self-interview (ACASI). Methods: The analysis is based on a subsample of over 700 never married girls aged 15-21 years in Kisumu, Kenya, drawn from a population based survey of over 2100 respondents. A questionnaire with 69 questions was used, two thirds of which were considered sensitive, including questions about risky sexual behaviour, alcohol and drug use, contraceptive practice, pregnancy, induced abortions, and births. Results: ACASI produced significantly higher reporting of sex with a relative, stranger, or older man, and higher reporting of coerced sex. However, differences by mode for ever had sex and sex with a boyfriend were not significant. Relative to ACASI, the interviewer administered mode produced highly consistent reporting of sexual activity, both within the main interview and between the main and exit interviews. Conclusions: Both the mode of survey administration and the probing for various behaviours significantly affect the observed prevalence of sexual activity. The ACASI results suggest that adolescent girls in Kenya have more complex and perilous sex lives than traditional face to face surveys of sexual activity indicate. The level of consistency in the interviewer mode is argued to be suspect, particularly given the much lower levels of reporting, relative to ACASI, for types of sexual partners and coerced sexual activity. I n sub-Saharan Africa, where the major route of transmission of HIV is through heterosexual intercourse and where levels of infection among young people, particularly adolescent girls, are high, the accuracy of information on sexual activity prior to marriage is critically important for policy and programme purposes.1 2 Yet recent studies from the region raise questions about the validity of reporting of sexual behaviour. For instance, an analysis of trends in age at first sex in Africa using the Demographic and Health Surveys revealed discrepancies in reporting within birth cohorts, consistent with young women denying and young men exaggerating their sexual activity. 3 An epidemiological investigation of the large gender disparity in HIV prevalence among young people in two African cities revealed HIV prevalence to be high among women reporting one sexual partner and few episodes of sexual intercourse, a pattern suggesting considerable underreporting of risky sexual behaviour among young women. 4 These concerns about data quality underscore the importance of identifying the optimal mode of collecting information from young people. In previously published research on the effects of interview mode on the reporting of sensitive behaviour in Nyeri and Kisumu districts in Kenya, we evaluated whether audio computer assisted self-interviewing (ACASI) produced more credible data than interviewer administered and paper and pencil self-administ...

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Does audio computer-assisted self-interviewing (ACASI) produce more valid reporting of sexual activity and related behaviors than face-to-face interviews or self-administered interviews? This analysis, based on data collected from over 6,000 unmarried adolescents in two districts of Kenya--Nyeri and Kisumu--indicates substantial and significant differences in reported rates of premarital sex across interview modes, although not always in the expected direction. Our assumption that girls underreport sexual activity in face-to-face interviews by comparison with ACASI is not confirmed by the Nyeri data, but our results from Kisumu are considerably more promising. As for boys, who we believe exaggerate their level of sexual activity in face-to-face interviews, a more nuanced set of expectations regarding the reporting of sensitive behaviors was offered; our results from Kisumu, although not always significant, by and large conform to expectations.