Adolescent Pregnancy Prevention: An Abstinence-centered Randomized Controlled Intervention in a Chilean Public High School

This study is an evaluation of TeenSTAR, an abstinence-based, teenage pregnancy prevention programme implemented in Santiago, Chile in the years 1996-2002. The study was intended to provide a strictly controlled setting for evaluating the effectiveness of a sex education programme. The authors have argued that while many studies have hinted at the positive impact of sex-education programmes in reducing teenage pregnancies, few had had the proper control measures needed to fully establish the causal role of an education programme. The study measured the rate of pregnancies over several cohorts of teenagers just entering high school.

The TeenSTAR programme itself was an abstinence-only sexual education programme stressing the importance of the biological and physiological aspects of fertility. It provided special training in fertility awareness, together with the psychological and personal aspects of sexuality using a combination of group discussions, brainstorming, fertility awareness instruction, homework, videotapes and skill building activities.

The TeenSTAR Intervention

The abstinence-only sexual education programme consisted of 14 units, spread out over the school year. Each unit was developed in one or more 45-minute classes depending on the achievement of the objectives by the students before going on to the next unit. The units covered the following range of subjects including:

• Differences between genders
• Identification of prejudices on male and female's characteristics
• Anatomy and physiology of human reproductive organs
• Puberty, fertility in women and fertility in men
• Fertility awareness, registration of fertility records (classes distributed along the course)
• Knowing emotions and controlling behaviour
• The manipulation of sexuality in media
• Self assurance and maintaining decisions
• Marriage and family
• Beginning of life, value of human life
• Family Planning Methods, contraception
• Pregnancy, delivery, breast feeding

Evaluation



The participants were 1,259 teenage girls, all regular high school students, white Hispanics, from middle and low-income families, 15 to 16 years olds enrolled in their first year at an all-girls high school in San Bernardo, Chile. The girls from the first cohort (1996) received no intervention but were tracked throughout the study. The girls from the second cohort (1997) were divided equally into two groups, and intervention and a control group, while the girls from the third cohort (1998) were also divided into two groups, but the intervention group was much larger, as a result of decisions made due to steep declines in the pregnancy rates among girls who had participated in the intervention in the 1997 year.

The pregnancy rates of the girls were then tracked throughout the duration of high school, which in Chile is 4 years. The study was thus active until 2002, when the last cohort of girls graduated. No further interventions were received by any of the cohorts during the second, third or fourth year of high school and there was no formal sex-education programme in the school previous to the 1997 intervention. The TeenSTAR programme has subsequently become mandatory for all students since 1999.

All clinical pregnancies that ended in term or preterm deliveries or in spontaneous abortion were registered by the school administration and attended at the hospital for pregnancy control and delivery. The data presented correspond to these pregnancies. The authors note however, that induced abortion is not legal in Chile, and therefore no reliable data on its rates among students is available.

Findings



The results of this study demonstrated that the TeenSTAR programme was extremely effective in reducing teenage pregnancies. While the authors do suggest that their results in these controlled conditions effectively indicate the causality of programme in reducing pregnancies, they do not attempt to explain what the causal mechanism is. This is notable because the programme is almost exclusively focused on abstinence and does not promote contraceptive use as a viable option other than in a brief passing reference in a single module. They suggest that more research is needed.



The authors believe that their study demonstrates that long-term, cognitive-behavioural interventions proposing abstinence can reduce unintended pregnancies among female high school students. The intervention produced the predicted impact of a significant reduction in pregnancy rates over long-term follow-up, though the authors admit that they do not have reliable data about the modifications on sexual activity and contraceptive use among the students during the follow-up period.

The authors also argue that in-school programmes must extend for at least one semester - ideally for a full year - in order to generate the necessary changes in habits or reinforce the desired existing habits and behaviours. They stress their belief that teachers were essential to TeenSTAR's success and that they are effective monitors for this type of programme. Teachers, according to the authors, are able to propose a comprehensive sex education programme and become involved without affecting their other teaching activities. The authors recognise a few limitations within their study:

• Measurement of pregnancy rates was complicated because induced abortion is illegal in Chile and it was not possible to know if there were any in the control or study groups.
• Reliable data on sexual activity and contraceptive use was not obtained in this study.

Nevertheless, the authors concluded that this intervention was effective in encouraging abstinence and reducing rates of pregnancy. They believe that the focus on abstinence-only programming can have a positive impact on girls' self-esteem and ability to negotiate in sexual settings.