I think I've heard of that theory in relation to natural gender selection. Something about if you BD the day before or the day of O it's more likely to result in a boy, but if you BD several days before O it's more likely to result in a girl because all the 'boy' sperm die off and the 'girl' sperm get to the egg. Can't remember what that theory is called! But it is just a theory I believe.

I don't know whether having an orgasm the day after sex would help in regards to the sperm getting to the egg. I think it's more that having an orgasm at the same time you have sex helps the little get through the cervix?? Not that an orgasm is necessary to get pg though!! LOL