"Adam and Eve could not have children while they were in the Garden of Eden.  They lacked the capacity to bear children in the innocent state in which they then existed. (2 Nephi 2:23)

"They had been given the gift of childbearing as an endowment from God.  The endowment of the capacity did not mean they had the means or understanding at the time to act upon it.  Without the fall, they would not have been able to act on the endowment.  They were like little children who are born male and female with the capacity to one day become parents, but who are immature and innocent, and therefore unable to bear children.

"The great offense was in Satan’s control of the timing.  Had they remained in the Garden throughout the Sabbath day of rest then they would have received the commandment to partake of the fruit in the Lord’s timing. At this point they would have moved from their innocent state into a condition not unlike the Millennial day.  The “fall” would have transitioned to a Terrestrial state, rather than a Telestial state." (Denver Snuffer: Adam and Eve)