[Antonello]

The cortisol level increase can happen after the rape, due to stress, and it might cause the woman's body to reject the egg, can't it?

Now, if you've got some study that you would like to proffer then I would be more than willing to look at it.

Since you asked:

From Sciencealerts.com:

...The objective of the current study was to assess HPA-axis functioning in female adolescents with rape-related PTSD, but no prior sexual trauma, in comparison to non-victimized controls....Compared to age-matched controls, adolescent rape victims with PTSD showed significantly reduced cortisol and DHEAS levels....(Emphasis mine)

So much for the theory that rape victims have elevated cortisol levels.

[philman_36]

Your link...Salivary cortisol and dehydroepiandrosterone sulfate in adolescent rape victims with post traumatic stress disorder

You should have, IMO, picked the title, which is a link, which would have brought you here...
Salivary cortisol and dehydroepiandrosterone sulfate in adolescent rape victims with post traumatic stress disorder
Conclusions
The results show evidence for a dysregulated HPA-axis in female adolescent victims of single sexual trauma with PTSD. The finding of hypocortisolism is consistent with endocrine dysfunctioning in chronic sexual abuse victims and may have clinical implications with regard to treatment possibilities.

[philman_36]

So much for the theory that rape victims have elevated cortisol levels.

So you disagree with the conclusions given in the second article?

[philman_36]

Here you go for some more...
Anxiety disorders and salivary cortisol levels in older adults: a population-based study
Conclusion
Older adults from the general population with long-lasting anxiety disorders had a lower cortisol awakening response than those without. This is consistent with the notion that chronic anxiety may result in downregulation of HPA-axis activity. Longitudinal studies are needed to confirm this mechanism.

Once again we see that chronic or "long term" stress/anxiety reduces cortisol production instead of increasing it. People become mentally acclimatized to whatever their situation is and the body reacts accordingly.