Congratulations for new parents and how they should respond
The dua in its Arabic wording from Hisn al-Muslim, with its English meaning.
بِسْمِ اللَّهِ الرَّحْمَٰنِ الرَّحِيمِ
Bismillahir-rahmanir-raheem
Each dua: the Arabic, then a transliteration to help you say it aloud, then its meaning.
((بَارَكَ اللَّهُ لَكَ فِي الْمَوْهُوبِ لَكَ، وَشَكَرْتَ الْوَاهِبَ، وَبَلَغَ أَشُدَّهُ، وَرُزِقْتَ بِرَّهُ)). وَيَرُدُّ عَلَيْهِ الْمُهَــــــنَّأُ فَيَقُولُ: ((بَارَكَ اللَّهُ لَكَ وَبَارَكَ عَلَيْكَ، وَجَزَاكَ اللَّهُ خَيْراً، وَرَزَقَكَ اللَّهُ مِثْلَهُ، وَأَجْزَلَ ثَوَابَكَ)).
Barakallahu laka fil-mawhoobi lak, washakartal-wahib, wabalagha ashuddah, waruziqta birrah. Wayaruddu 'alayhil-muhanna'u fayaqool: barakallahu laka wabaraka 'alayk, wajazakallahu khayra, warazaqakallahu mithlah, wa ajzala thawabak.
May Allah bless you with His gift to you and may you (the new parent) give thanks, may the child reach the maturity of years, and may you be granted its righteousness. The reply of the person being congratulated is to say: May Allah bless you, and shower His blessings upon you, and may Allah reward you well and bestow upon you its like and reward you abundantly
once
Source: Hisn al-Muslim by Saʿid ibn ʿAli ibn Wahf al-Qahtani. The Arabic is verbatim from the book; the English meaning is from the hisnmuslim.com English edition. The transliteration is generated by Waqtazan from the voweled Arabic as a reading aid — the Arabic and the recitation remain the reference. Virtues are quoted only from authentic hadith (al-Bukhari, Muslim, or graded sahih/hasan by al-Albani). Recitations: hisnmuslim.com.