In the developed world, abortions are common despite ubiquitous condoms, birth control and even the "morning after pill" - about 6.7 million per year.
In Canada, the teen pregnancy rate is 28 per 1000, with more than 50 percent of those ending in abortion, so a study in Canadian Medical Association Journal decided to see what was different about teens who had an abortion versus teens that did not.
The data were 431,623 daughters born in Ontario obtained from the Institute for Clinical Evaluative Sciences (ICES) and linked to other databases that provided information on mother-daughter pairs. There were 73,518 daughters whose mothers had had at least one abortion (exposed group) and 358,105 daughters whose mothers had none (unexposed group).
In the exposed group, teens with mothers who had an abortion, the probability of having an abortion during their teenage years was 10.1%, compared with 4.2% in the unexposed group, those with mothers who had not had an abortion. As the majority of those abortions (94.5%) occurred before 15 weeks gestation, it's unlikely that the reason was a genetic or birth defect in the fetus in most cases so it's reasonable to assume personal choice. .
There was also a dose-response effect: the greater number of abortions in the mother, the greater the number of abortions in her teenage daughter.
Study limitations include a lack of information on the fathers, the marital status and education levels of both mother and daughter, or family dynamics and attitudes.