Between Sunnah and Fajr Namaz read
Surah Alam Nashrah:
"Alam nashrah laka sadraka
WawadaAAna AAanka wizraka
Allathee anqada thahraka
WarafaAAna laka thikraka
Fa-inna maAAa alAAusri yusran
Inna maAAa alAAusri yusran
Fa-itha faraghta fainsab
Wa-ila rabbika fairghab"
and then read Surah Al Feel which is given below:
بِسْمِ اللَّهِّ اللَّهُمَّ جَنِّبْنَا الشَّيْطَانَ وَجَنِّبِ الشَّيْطَانَ مَا رَزَقْتَنَا
"I am having relations in the name of Allah. O Allah save us from Satan and keep him away from the children You grant us". The child that is born after the recitation of this dua will never be harmed by Satan.(Bukhari, Muslim)
Note: This dua must be read for if Allah's name is not taken, the Satan's sperm enters with the man's (As in marginal notes of Hisnul Hasin)