Rav Moshe Feinstein was asked (Igros Moshe YD 4:74) if it is permissible to schedule a date for a C-Section delivery for a woman who already had a Cesarean delivery and the Doctor's did not think she could have a natural delivery.
Rav Moshe says it is not halachicly acceptable to schedule a date and she should wait until she goes into labor before they deliver the baby. He gives three reasons for this. First he says that even if this operation will need to be done eventually at the time of childbirth, still we don't opt to do any dangerous procedure before it is necessary as the principal of Chayei Sha'a (that every moment of life is precious and must be saved) applies to the case of operations as well.
Secondly, says Rav Moshe, unless there is some danger, it is surely better for the infant in the mother's womb until nature sends him out. Therefore we have no permission to take the baby out against its best interest. Lastly say Rav Moshe, the baby may go against the odds and come out naturally and not need a C-Section after all. Therefore for these three reason it is best not to schedule a C-Section until the baby has run its natural course in the womb.
This all of course only applies, says Rav Moshe, if there is no danger to the mother or the baby by its remaining there until the end.
Important Note: We bring this tshuvah as a starting point for discussion and not to convey any halacha. We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. One should learn the tshuva to verify the accuracy of our interpretation. Please understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.