بسم الله الرحمن الرحيم
Husband and wife should recite the following ayah during pregnancy as much as they can:
رَبَّنَا هَبْ لَنَا مِنْ أَزْوَاجِنَا وَذُرِّيَّاتِنَا قُرَّةَ أَعْيُنٍ وَاجْعَلْنَا لِلْمُتَّقِينَ إِمَاماً [الفرقان : 74]
Besides, both should follow the commandments of Shariah completely and should not take any step against the Shariah. In-sha-Allah, they will be blessed with pious children.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.