he Messenger of Allah ﷺ said: whoever says this Dua and the wife was pregnant from that night, Shaytan will never be able to harm the child.
بِسْمِ اللهِ اللّٰهُمَّ جَنِّبْنَا الشَّيْطَانَ ، وَجَنِّبِ الشَّيْطَانَ مَا رَزَقْـتَنَا
In the Name of Allah. O Allah, keep the shaytaan away from us and keep the shaytaan away from what You have blessed us with.
Sahi Bukhari - Muslim No# 1434