بسم الله الرحمن الرحيم
During the pregnancy and in common conditions the parents should read this verse and they should recite it seven times after each salah. In-shaAllah, they will be blessed with child who shall be pious. The verse is as follows:
رَبَّنَا هَبْ لَنَا مِنْ أَزْوَاجِنَا وَذُرِّيَّاتِنَا قُرَّةَ أَعْيُنٍ وَاجْعَلْنَا لِلْمُتَّقِينَ إِمَاماً.
However, recitation of Surah Maryam is useful during pregnancy.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.