I learned in maseches "Yoma" (12a) that Yocheved's pregnancy and labor of Moshe were painless.
1) The gemara says that righteous women don't suffer due to the curse of Chavah. Therefore, would it be that all of Yocheved's pregnancies and labors were painless and that that Moshe was unique with the room being lit up and his having been born mahul. Could it be that the baby also has an effect on a painless labor?
2) Where our other sources that would discuss Yocheved's painless birth of Moshe in specific or the concept of painless labor in general?
3) The gemara mentions that there is a hekeish between the pregnancy and birth to teach that both were painless. We find this hekeish would also apply to the birth of Kayin (Bireishis:4; 1), especially since, as RaSh"I notes, Kayin and Hevel were born before the sin of Adam and Chavah and therefore Chavah's labor with them were painless. This can be another example that would follow the gemara's teaching relating to the hekeish by Yocheved. There are, of course, other examples of this hekeish in The Torah. Is the gemara teaching that everywhere there's a hekeish, it was a painless birth?
1) Perhaps you're right about all Yocheved's labors.
2) Midrash Rabah (Shemos 1:23) brings the same Drasha. The Etz Yosef there adds that Rachel suffered only because of Yakov's curse and Rivka suffered because of Esav.
3) Rashi (DH Makish Leidasa) learns that only here do we say the Hekesh because the Pasuk should not say here va'Tahar since pregnancy started before Amram returned to his wife, which is mentioned in the previous Pasuk.
I might add: Please do not use Torah sources to make incorrect deductions to further preconceived opinions when discussing relieving pain in childbirth.
All the best,