Did Adam and Chava have a child before they sinned? Was childbirth not painful before they sinned?

Question

Did Adam and Chava have a child before they sinned? Was childbirth not painful before they sinned?

In Bereshit 3:16, it says, To the woman He said, "I shall surely increase your sorrow and your pregnancy; in pain you shall bear children. And to your husband will be your desire, and he will rule over you." https://www.chabad.org/library/bible_cdo/aid/8167/showrashi/true#v=16

Does this verse imply that before Adam and Chava sinned, childbirth was not painful? What do our rabbis of blessed memory say? (Update: if it is allowed to edit the question, then I would say, that I would also accept pre-rabbinic authoritative sources; if not, my question stands as it is/was.)

Answer 1

According to Sforno, yes: both pain and other issues on childbirth and pregnancy mentioned in this verse indicates that the exact opposite occurred before their sin.

her pregnancy will be exactly the opposite of what it had been before she sinned. (Translation from Sefaria)

On regard the other question, if they had a child before they sinned, the answer is also yes. Check the words of the first Rashi on 4:1 in which he says that this event (the birth of Cain) occurred before their sin.

Now the man knew: [This took place], prior to the above episode, before he sinned and was banished from the Garden of Eden. Also the conception and the birth [took place before], for if it were written: וַיֵּדַע אָדָם it would mean that after he had been banished, he had sons. — [from Sanh. 38b]

Answer 2

Sanhedrin 38b contains a chronology of Adam's first day, in which the births of Cain and Abel precede Adam and Eve's sin:

Rabbi Yoḥanan bar Ḥanina says: Daytime is twelve hours long, and the day Adam the first man was created was divided as follows: In the first hour of the day, his dust was gathered. In the second, an undefined figure was fashioned. In the third, his limbs were extended. In the fourth, a soul was cast into him. In the fifth, he stood on his legs. In the sixth, he called the creatures by the names he gave them. In the seventh, Eve was paired with him. In the eighth, they arose to the bed two, and descended four, i.e., Cain and Abel were immediately born. In the ninth, he was commanded not to eat of the Tree of Knowledge. In the tenth, he sinned. In the eleventh, he was judged. In the twelfth, he was expelled and left the Garden of Eden

I think the implication is as you suggested, that those births would not have been as painful as those following the sin.

Answer 3

The Sefer HaYovelot (or Yovelim) is the oldest existing Midrash/perush on the Chumash (that we have today), and it dates back to the times of the Hashmonaim.

It states that Adam and Hava had children only after the Chet

ובראש החודש הרביעי יצאו האדם ואשתו מגן עדן וישבו בארץ אלדד בארץ אשר נבראו שם

And on the new moon of the fourth month, Adam and his wife went forth from the Garden of Eden, and they dwelt in the land of ’Eldâ, in the land of their creation.

ויקרא האדם שם אשתו חוה ולא היה להם בן עד שנת היובל הראשון:

And Adam called the name of his wife Hava. And they had no son till the first jubilee,

ואחרי כן ידע אותה

and after this he knew her