Dubno Maggid: Shemot II

We differentiate between the righteous who were born with higher souls and those who were not but worked hard to perfect themselves in order to achieve their righteousness.

The one who works can take more credit for his or her righteous deeds. The verse goes out of its way to say that the midwives acted out of their awe of God, to indicate that they were not born as righteous people, but achieved the high levels of attachment through their work motivated by their awe of God.