I say, and with Allah's success: The Prophet Muhammad (peace be upon him and his family) definitely performed the adhan in the newborn's ear, but as for his performing the adhan for prayer, we are still hesitant about that. The reason for the Prophet (peace be upon him and his family) abandoning this act of worship and not being consistent in it, despite the clear virtues mentioned in the authentic reports, is that the Prophet's (peace be upon him and his family) habit was to consistently perform actions he undertook. He was engaged in the responsibilities of the message and the interests of the Sharia, such as fighting, settling disputes among people, and other matters that are more important than the adhan. If he had been consistent in performing the adhan, it would have disrupted these important matters. The Prophet Muhammad (peace be upon him and his family) had five muadhdhin (callers to prayer): Bilal, Ibn Umm Maktum, Sa'd al-Qarzi, Abu Mahdhura, and Ziyad ibn al-Harith al-Sudai. For more details, refer to "The Best Report on the Adhan of the Best of Mankind" by Imam al-Laknawi. And Allah knows best.