If a physician sees someone in the aftermath of an abortion and diagnoses Post Traumatic Stress Disorder, with abortion as the stressor, it would not be questioned. With an abortion, which might have carried with it a good deal of uncertainty and pressure, the individual is swept along without sorting out and thinking through issues involved. In all major crisis situations, there is a kind of helplessness, and people are very suggestive. Pressure can persuade the individual to go ahead and get the abortion done. After it is over, the interest is in going ahead with the person's life and forgetting about it.
Denial comes into play.
The person doesn't want to think or talk about it, she wants to keep it secret. There is a sealing over of the whole experience. Denial, the death of a child or a close relative, repression, or erasing from conscious awareness can lead the individual to not think of the abortion for some time afterwards. But to do this requires a good bit of mental energy. When memories do begin to come back, there may be dreams of the baby or recollections of the abortion clinic.