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The present study was performed in order to update available data on puberty in South African women gathered from studies among a variety of South African population groups and to compare our findings with these previous studies in order to identify any change. In addition, the children's social environment was evaluated to see if it had any influence on the timing of puberty. This study is important because a decrease in the age of onset of the various stages of puberty would be expected as the socio-economic status of the population increases. We would expect that once socio-economic and therefore nutritional equality between different communities exists, there would be little difference between the age at which children attain puberty. An absence in the trend toward a younger onset of puberty would be a cause for concern as this would imply that there has been no improvement in living conditions from the time of the original study. A relationship has also been shown to exist between an earlier age at menarche and an increased risk of breast cancer (Pike 1983), an increased risk of coronary heart disease (Colditz 1987), shorter adult height (Shangold 1989), earlier initiation of sexual activity (Soefer 1985), earlier first pregnancy, (Sandler 1984) and larger family size (Frisch 1978). This implies that as the age at which children pass through puberty decreases, it becomes increasingly important to introduce both sexual education and the availability of contraception at a correspondingly earlier age in order to avoid the tragedies of teenage pregnancies.

Thesis (Ph. D.)--University of Chicago, 2003. / Includes bibliographical references (leaves 179-193). Also available on the Internet.

Thesis (Ph. D.)--University of Chicago, Department of Psychology, Committee on Human Development, June 2003. / Includes bibliographical references. Also available on the Internet.

Teenage pregnancy is a global public health problem, which results in inevitable interruptions in their education. In some instances, dropping out of school is temporary, but some of teenagers do not return to school. The dual responsibility of parenting and school work often results in poor scholastic performance, adding to the burden of a limited education and scarce employment opportunities. Since 2004, schools in Soshanguve have been requesting urgent preventive interventions regarding teenage pregnancy, which prompted the need for this study. The aim of the study was to determine the pattern of relationships, perceptions and the socio-cultural environments of pregnant teenagers in Soshanguve. A qualitative exploratory, descriptive and contextual design was used for the study. Participants comprised teenagers from Soshanguve secondary schools, who visited the clinic for ante-natal or post-natal care. A purposive sampling method was used and the sample size was determined by saturation. Semi-structured interviews were conducted with 30 participants. Tesch’s approach, using open coding and a template analysis system, was utilised for data analysis. Teenagers lacked information about menarche and menstruation, leaving them unprepared for their pregnancies. Participants did not realise the consequences of their love and sex relationships. Circumstances around their lives and the socio-cultural environments contributed to their pregnancies, resulting in teenagers showing regret, shame, denial and some accepting their pregnancies. Communication about sexuality was lacking and teenagers had no risk perceptions teenage pregnancy is urgently needed.

Thesis (M. P. H.)--University of Hong Kong, 2007.

Thesis (M. P. H.)--University of Hong Kong, 2007. / Also available in print.

Thesis (M.A.)--University of Texas at Austin, 1981. / Vita. Includes bibliographical references.

Demographic and sociological theories usually do not incorporate biological variable into their explanations. This dissertation addresses this void by examining the influence of age at menarche on age at first birth, the event of a first birth, and the number of children ever born (CEB). I expand on Demographic Transition theory by incorporating biology as one of the effects of modernization that has an effect on reducing fertility. Age at menarche decreases as a society modernizes. I use data from the 1995 Survey of Family Growth, Cycle V for the U.S., and the 1997 China Survey of Population and Reproductive Health. I further stratify the data into five race/ethnic groups: Chinese Han, Chinese minorities, U.S. Non-Hispanic Whites, U.S. Non-Hispanic Blacks, and U.S. Hispanics of Mexican origin. I use four different statistical methods to model my dependent variables: Ordinary Least Squares Regression, Cox Proportional Hazard Analysis, Poisson Regression, and Negative Binominal Regression. My first major finding is that the younger a woman is when reaching menarche, the younger she will be when giving birth to her first child. Second, the younger a woman is when reaching menarche, the longer the duration to a first birth and the less likely she is to experience a first birth. These two results are consistent in all the groups I analyze. Third, the younger a woman when reaching menarche, the fewer children she will produce. The U.S. Mexican-Origin women are an exception in this final outcome. It is well known that as a society modernizes, age at menarche decreases. Analyses in my dissertation indicate that as women’s ages at menarche decrease, their ages at giving birth to the first child also decrease, but their chances of having a first birth also decrease and their waiting time for having the first birth increases. Also, fertility will decline as age at menarche declines.

Demographic and sociological theories usually do not incorporate biological variable into their explanations. This dissertation addresses this void by examining the influence of age at menarche on age at first birth, the event of a first birth, and the number of children ever born (CEB). I expand on Demographic Transition theory by incorporating biology as one of the effects of modernization that has an effect on reducing fertility. Age at menarche decreases as a society modernizes. I use data from the 1995 Survey of Family Growth, Cycle V for the U.S., and the 1997 China Survey of Population and Reproductive Health. I further stratify the data into five race/ethnic groups: Chinese Han, Chinese minorities, U.S. Non-Hispanic Whites, U.S. Non-Hispanic Blacks, and U.S. Hispanics of Mexican origin. I use four different statistical methods to model my dependent variables: Ordinary Least Squares Regression, Cox Proportional Hazard Analysis, Poisson Regression, and Negative Binominal Regression. My first major finding is that the younger a woman is when reaching menarche, the younger she will be when giving birth to her first child. Second, the younger a woman is when reaching menarche, the longer the duration to a first birth and the less likely she is to experience a first birth. These two results are consistent in all the groups I analyze. Third, the younger a woman when reaching menarche, the fewer children she will produce. The U.S. Mexican-Origin women are an exception in this final outcome. It is well known that as a society modernizes, age at menarche decreases. Analyses in my dissertation indicate that as women’s ages at menarche decrease, their ages at giving birth to the first child also decrease, but their chances of having a first birth also decrease and their waiting time for having the first birth increases. Also, fertility will decline as age at menarche declines.