Dua when congratulating on a newborn
بَارَكَ اللهُ لَكَ فِي الْمَوْهُوبِ لَك،...
بَارَكَ اللهُ لَكَ فِي الْمَوْهُوبِ لَك، وَشَكَرْتَ الْوَاهِبَ، وَبَلَغَ أَشُدَّهُ، وَرُزِقْتَ بِرَّهُ
Barakal-lahu laka fil-mawhoobi lak, washakartil-wahib, wabalagha ashuddah, wuriziqta birrah
Translation
May Allah bless you with what He has bestowed and may you give thanks to the Giver, and may the child reach the maturity of years, and may you be granted its righteousness.
When to recite
Said to congratulate someone on the birth of a new child.
Source / Reference
Ibn Sunni, Al-Hakim