Answer:
(Fatwa: 1422/1136=L=1430)
We do not remember any dua mentioned in hadith books about birth of baby girl. But, treating daughters with good conduct is promised to be a cause of deliverance from the Fire.
The age of 42 is not too old to have a baby.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
