For new baby born, should we make azan to right-ear and iqamat to left-ear, similarly for dead body when we burry it. Is it bid'ah ?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Calling the Athaan in the right ear of a newborn is desirable for the Hadeeth of Abu Raafi’ who said: “I saw the Prophet calling the Athaan in the ear of Al-Hasan ibn ‘Ali when Faatimah, may Allah be pleased with her, gave birth to him.” [Abu Daawod and At-Tirmithi who graded it as sound]

As for calling the Iqaamah in the left ear of a newborn, two Ahadeeth are reported in this concern but both of them are unauthentic.

The first Hadeeth is reported from Al-Hasan ibn ‘Ali from the Prophet that he said: "If one calls the Athaan in the right ear of a new born and the Iqaamah in his left ear, Umm As-Sibyaan (a kind of disease) will not affect him." [Al-Bayhaqi and Abu Y'ala] Shaykh Al-Albaani classified it as a fabricated Hadeeth]

The second Hadeeth is reported from Ibn ‘Abbas that the Prophet called the Athaan in the right ear of al-Hasan () and the Iqaamah in his left ear.” [Al-Bayhaqi who said that the chains of narration of both Ahadeeth are weak. The same practice is also reported from ‘Umar ibn Abdul-Azeez but Imam Ibn Hajar considered it unauthentic [Al-Talkhees Al-Habeer]

Therefore, it is desirable to call the Athaan in the right ear of a newborn, but neither the Athaan nor the Iqaamah should be called in his left ear.

Imam Ibn Qudamah wrote in Al-Mughni: “Some scholars said that it is desirable to call the Athaan in the ear of a newborn.”

There is no basis for calling the Athaan in the ear of a dead person; it is an innovation, and every innovation is a misguidance, and every misguidance is in Hellfire.

Allah knows best.