If Eve was with child when God created her - then Cain (& possibly Able) would have been born free of sin. Thus the first Sin of Adam & Eve would not have been passed on to Cain until he (they) would have sinned themselves. Thus it is inconvincible that Eve was PG with Cain.
Would Cain or Abel have been born free of sin if Adam knew Eve before she brought forth the one of which she created with out of Spirit?
If she was created with child, granted the child in her generated out of Spirit would have been Holy. Just as it is stated of Jesus in Matt 1:20
But the sign would always have been, a virgin shall be with child and [ understood, a virgin] would bring forth.
BTW this will be the last I say about this. The only reason I brought it up is because; Virgin, childbirth definitely [because of sinlessness] has something to do with redemption and I find it interesting that because Prov 30:20 associates eating and sex that Satan might have adulterated
the first to be born by deceiving Eve into having Adam lust her before bringing forth her first born. The need for redemption. Thus the fruit of the tree of the knowledge of good and evil.
Consider; Redemption through the blood of Christ had been foreordained before this in the garden took place.
Consider also if the answer is, Yes to the following question, "Did Satan the devil already need to be destroyed before Adam was created," ?
How was God going to destroy him?
Heb 2:14 Seeing, then, the children have partaken of flesh and blood, he himself also in like manner did take part of the same, that through death he might destroy him having the power of death -- that is, the devil --
God was going to destroy the devil through death. Where was death going to come from? Does redemption have anything to do with death?