Would she who gave birth without pain receive the reward for the pain of childbirth?

Everything that afflicts a Muslim of fatigue, hardship, or pain, God expiates his sins by it.

There is no objection to using what alleviates the pain of childbirth or completely prevents it, for the easier and simpler the act, the closer it is to the love of God.

Sheikh Ibn Uthaymeen was asked about the permissibility of taking an anesthetic injection to alleviate the pain of childbirth, and he replied that there is no harm in it, because it is enjoying the blessings of God that He loves His servants to enjoy, and God loves ease for His servants.

As for the amount of reward for the hardship of childbirth, it is up to God Almighty.