Rav Moshe (Dibros 86) expresses an idea that if Hashem commands the mitzvah of פרו ורבו, even if it would otherwise be a situation of danger, the very fact that there is a mitzvah to do it anyway, indicates that there is divine protection. He actually uses this idea l'halacha in igros moshe to explain why he considers it forbidden to induce labor. The promise that Hashem makes to protect during child birth is only for those who go into labor naturally, and not when it is induced.
Based on this assumption, Rav Moshe asks on Rashi's interpretation of the mashal - Leave the drunkard and let him fall alone. Rashi explains that when a woman gets pregnant she needs rachamei shamayim to go through child birth, by Hashem leaving her alone and not being mashgiach on her, she will die on her own. This implies that childbirth is inherently dangerous which Rav Moshe points out contradicts the idea that it has an automatic divine protection?
To reconcile Rav Moshe's idea with Rashi, it seems that the concept of divine protection is not that Hashem made the normal course of the world for woman to give birth and it not to be dangerous. Rather, by commanding people to procreate, G-d provides the assurance that for every single situation He will watch and protect. Therefore, in a situation where one has other aveiros that they are guilty of, Hashem simply removes his divine protection, as Rashi explains, and the drunkard falls by himself.