The United Kingdom has one of the highest teenage pregnancy rates in Western Europe with a high proportion of unintended pregnancies resulting in termination. General practice is one source of contraceptive and sexual advice for teenagers but it is difficult to target young women most at risk. This study was performed to determine whether it was possible to identify any markers that could alert general practitioners to the need to give appropriate opportunistic preventive advice. This was a retrospective case-control study in which the general practice medical records of young women with a recorded history of termination of pregnancy resulting from conception between the ages of 13-19 years inclusive were examined for details of consultations and contraceptive provision prior to conception. Where appropriate, comparison was made with an age and practice-matched control group. A total of 53 cases were identified and compared with 159 controls. In the 12 months prior to conception approximately half of the cases had discussed contraception and two-fifths had been prescribed oral contraception. A significantly higher proportion of cases than controls had consulted for emergency contraception and also for urinary tract symptoms. Weaker associations were also found with younger age of starting contraception, and also recorded side-effects or dissatisfaction with contraception. Lapsed contraception and previous pregnancy were noted as other potential markers of risk. The findings from this study may assist primary care professionals in focussing opportunistic sexual health interventions at some teenagers who are at higher risk of unintended pregnancy.