حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنْ سَالِمٍ، عَنْ كُرَيْبٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ “‏ لَوْ أَنَّ أَحَدَكُمْ إِذَا أَرَادَ أَنْ يَأْتِيَ أَهْلَهُ فَقَالَ بِاسْمِ اللَّهِ، اللَّهُمَّ جَنِّبْنَا الشَّيْطَانَ، وَجَنِّبِ الشَّيْطَانَ مَا رَزَقْتَنَا‏.‏ فَإِنَّهُ إِنْ يُقَدَّرْ بَيْنَهُمَا وَلَدٌ فِي ذَلِكَ لَمْ يَضُرُّهُ شَيْطَانٌ أَبَدًا ‏”‏‏.‏

Narrated Ibn `Abbas: Allah’s Messenger (ﷺ) said, “If anyone of you, when intending to have a sexual relation (sleep) with his wife, says: , Satan would never harm that child, should it be ordained that they will have one. (Because of that sleep).

Sahih Bukhari
Reference: Sahih al-Bukhari 7396 (Oneness, Uniqueness of Allah (Tawheed))
In-book reference:Book 97, Hadith 25

AND why you need to do that in the first place? Why it is important that you have a simple act and mindfulness about Allah even on those moments? Because that will probably set the path of Jannah or Jahannam for your child, And how is that? To understand that you have to know shaitan, Read few things from here if you are really serious!

But one extra prerequisite is to make WUDU. And Allah knows best.