Asma', daughter of Abu Bakr, reported that when she migrated to Allah's Messenger (ﷺ) in Medina she was in the family way with Abdullah b. Zubair in her womb.
Sahih Muslim Book 38, Hadith 33
← Previous Hadith I set out (for migration to Medina) as I was in the advanced stage of pregnancy. I came to Medina and got down at the place known as Quba' and gave birth to a child there. Then I came to Allah's Messenger (may peace he upon him). He placed him (the child) in his lap and then commanded for the dates to be brought. He chewed them and then put the saliva in his mouth. The first thing which went into his stomach was the saliva of Allah's Messenger (ﷺ). He then rubbed his palate with dates and then invoked blessings for him and blessed him. He was the first child who was born in Islam (after Migration).

Sahih Muslim Book 38, Hadith 32 Next Hadith → 'A'isha reported that the new-born infants were brought to Allah's Messenger (ﷺ). He blessed them and rubbed their palates with dates.

Sahih Muslim Book 38, Hadith 34