Or as an hidden untimely birth - As an abortion which is hid, or concealed; that is, which is soon removed from the sight. So the Psalmist, Psalms 58:8 :
As a snail which melteth, let thom dissolve;
As the untimely birth of a woman, that they may not see the sun.
Septuagint ἔκτρωμα ektrōma, the same word which is used by Paul in 1 Corinthians 15:8, with reference to himself; see the notes at that place.
I had not been - I should have perished; I should not have been a man, as I now am, subject to calamity. The meaning is, that he would have been taken away and concealed, as such an untimely birth is, and that he would never have been numbered among the living and the suffering.
As infants which never saw light - Job expresses here no opinion of their future condition, or on the question whether such infants had immortal souls. He is simply saying that his lot would have been as theirs was, and that he would have been saved from the sorrows which he now experienced.