[xzins]

Just because there’s ovulation and intercourse doesn’t necessarily mean there will be fertilization and implantation. There are other factors such as at this link:

http://www.health.harvard.edu/newsletters/Harvard_Mental_Health_Letter/2009/May/Conditions-That-Affect-Fertility

[editor-surveyor]

Yes, of course there are other factors that may intervene, but I think he was expecting a more general answer.