Quote:
Originally Posted by Twosugars
More than that 
It activates neuronal impulses leading to enhancement of vaginal blood flow, increased lubrication, oxygen and temperature, and an altered position of the cervix, which paradoxically slows down the sperm and improves their motility. |
I can believe that yet hormonally at times in the reproductive cycle there are times when this process is more likely too, so an orgasm is not the only way for the stars to align that makes having a baby more likely.