Verses with the word firstborn in the New Testament (7 verses):

Matthew 1:25
And knew her not till she had brought forth her firstborn son: and he called his name JESUS.

Luke 2:7
And she brought forth her firstborn son, and wrapped him in swaddling clothes, and laid him in a manger; because there was no room for them in the inn.

Romans 8:29
For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that he might be the firstborn among many brethren.

Colossians 1:15
Who is the image of the invisible God, the firstborn of every creature:

Colossians 1:18
And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence.

Hebrews 11:28
Through faith he kept the passover, and the sprinkling of blood, lest he that destroyed the firstborn should touch them.

Hebrews 12:23
To the general assembly and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect,