The incidence of repeat induced abortion--a prospective cohort study

To measure the cumulative incidence of first and second repeat induced abortion and what differentiates first-time repeaters from non-repeaters.

The study population comprised 2,925 women who had their first induced abortion at the University Hospital of Trondheim, Norway between January 1, 1987 and December 31, 1991. Repeat induced abortion within the study period was measured as a cumulative incidence of second and third induced abortion. Survival analyses and logistic regression analysis were applied using 'repeater' as the dependent variable.

The cumulative incidence of second induced abortion was 3.7% at end of first year, 7.1% at end of second year, 9.9% at the end of third year, and 12.3% at four completed years of observation. The cumulative incidence of third induced abortion was 0.1% at the end of first year, 0.6% at the end of second, 1.3% at the end of third and 2.0% at four years of observation. The cumulative incidence of the third abortion, measured as the time at risk from the second to the third abortion, remained twice that of the cumulative incidence of the second abortion after one year of observation (p < 0.001). At the first abortion, variables predicting a risk for repeat induced abortion were age, occupational status and becoming pregnant as a result of a contraceptive failure.

Repeat induced abortion in inevitable. The incidence of repeat induced abortions doubled from the second to the third abortion, indicating that the moral threshold for choosing an abortion after recognition of an unplanned pregnancy is the first induced abortion. More detailed studies on the effect of intensified contraceptive counselling programs after the first abortion are needed.