Question: [Yebamoth 61b](http://halakhah.com/yebamoth/yebamoth_61.html#PARTb) discusses the positive commandment of being fruitful and multiplying. As far as I am aware, one makes no blessing before intercourse. Why not?

Please cite sources!

Answer: 
UPDATE FOUND THIS:

> 
> The גליוני הש"ס to Berachos 35a discusses that there should be a
>  blessing on marital relations, and concludes that Birkas Ha'erusin
>  accomplishes that. It would seem he held this concept can extend to
>  other pleasures, although this could still be in the realm of "a need
>  of the body.
>  <https://judaism.stackexchange.com/a/34856/1857>
> 
> 
>
The Shulchan Aruch ([EH 63:2](http://beta.hebrewbooks.org/tursa.aspx?a=eh_x7690)) actually does quote a beracha from the Bahag, to be made after the first bi'ah with a Betula. The Aruch HaShulchan says that we are not noheg to say this beracha anymore.

However, that beracha is not a beracha on the mitzva, but it appears to be a birkas hashevach. The reason we don't make a beracha on bi'ah is because it is contingent on another party. If she says no, you are not supposed to have bi'ah.