Selection bias in a study on how women experienced induced abortion

Objective. One third of the women who had an induced abortion at the department of gynecology and obstetrics in Malmö 1989 refused to participate in an interview a year later to explore their experience and the care they had received. Using data from the mandatory preoperative visit it was then possible to compare participants with no-participants with regard to socio-demographic characteristics, reproductive history and stated reason for abortion. By continued follow-up of medical records it has furthermore been possible to ascertain how many women conceived within a year, and how many of them applied for another abortion and how many elected to continue the pregnancy to term. Setting. Department of Obstetrics and Gynecology, Lund University, University Hospital, Malmö, Sweden. This is the sole referral hospital serving the population of Malmö (approx. 230 000). Subjects. All 1285 women who underwent induced abortion at the department in 1989. + Study design. In each case information on socio-demographic characteristics, reproductive history and stated reasons for abortion was collected at the mandatory clinical visit prior to the abortion. This information was used for comparison of participants and non-participants in the planned 1-year follow-up interview. Results. Young, unmarried women of low educational status and without full-time employment or studying were overrepresented in the non-participant group. The proportion of women with children was however smaller in that group. Within 12 months after the abortion, 118 women 66 (7.7%) of the participants in the follow-up interview and 52 (12%) of the non-participants conceived again but elected to continue the pregnancy to term ( P