Genesis 38:27-29

The Voice

²⁷ When the time came for her to deliver, she discovered she was carrying twins. ²⁸ While she was in labor, one of them put out a hand; and the midwife tied a scarlet thread on it, so she would know which one came out first. ²⁹ But just then he drew his hand back into the womb, and his brother came out first. The midwife had never seen anything quite like this.

So the child was named Perez.