@jupiter,
You can have it as long as you two are enjoying.
Even the morning before delivery is safe as long as you are not doing it in a way you are hurting the wife and the foetus.
There is nothing like grime as @sheep has put it.this is ignorant of the highest order.
Infact not even the HIV virus can pass to the foetus ......
Disclaimer : This is my opinion and not a recommendation.
"You're not supposed to be so blind with patriotism that you can't face reality. Wrong is wrong, no matter who says it". Malcolm X