Praise be to Allah.
Du`a before sex
Among the manners prescribed by the Shari’ah is that the Muslim should say when he commences intercourse with his wife :
"In the Name of Allah, Oh Allah, shield us from Satan and keep him away from us and from what You [may] bestow upon us (i.e. children)" Narrated by Al-Bukhari, Fath ul-Bari No. 138)
Transliteration of du`a before sex
This opening invocation is useful in that if Allah blesses the husband and the wife with a child, this child will not be harmed by Satan.
And Allah knows best.