The Value of Labor Pains

Nietzsche seems to implicitly reject Spinoza's proposition that Pain is a sign of weakening.  However, his perhaps most famous articulation of his opposition to the latter--"What does not kill me only makes me stronger", #8 of the 'Maxims and Arrows' section of Twilight of the Idols--has limited evidentiary value, especially since, as is less well-known, the assertion is preceded by the qualification "From the military school of life."  Instead, a potentially more compelling counter-example is birth labor pains, which cannot easily be classified as a "weakening" process.  The additional advantage of that example is that the claim of constructive value for its instance of Pain can also be directed at his primary opponent on the topic--the Theology for which labor pain is a 'divine punishment', though such a challenge would be more effective if grounded in a principle in terms of which Pain can be interpreted as a positive experience.