JOEL - When you put it like that I think my wife would rather go to Hell :-)
Our Doctrine and Covenants states:

"In the celestial glory there are three heavens or degrees; and in order to obtain the highest, a man must enter into this order of the priesthood [meaning the new and everlasting covenant of marriage]; And if he does not, he cannot obtain it. He may enter into the other, but that is the end of his kingdom; he cannot have an increase" (D&C 131:1-4).

One aspect of this "increase" includes the ability to create spirit children after a husband and wife have succesfully entered into the Celestial kingdom in the next life. These spirit children will eventually obtain bodies of flesh and bone and live on an earth as we do now.
The prophet Joseph Smith said:

"Except a man and his wife enter into an everlasting covenant and be married for eternity, while in this probation, by the power and authority of the Holy Priesthood, they will cease to increase when they die; that is, they will not have any children after the resurrection. But those who are married by the power and authority of the priesthood in this life, and continue without committing the sin against the Holy Ghost, will continue to increase and have children in the celestial glory" (TPJS, pp. 300-301).

This is pretty much all we know about it. The exact method of how spirit children are created has not been revealed to us. To describe it with a mortal term such as "eternally pregnant", places an inaccurate and unnecessary negative connotation on a process that we know nothing about.
After Eve took the forbidden fruit and became mortal, God said to her:
"I will greatly multiply thy sorrow and thy conception; in sorrow thou shalt bring forth children;" (Gen 3:16).
If God is going to "greatly multiply" the sorrow(pain) associated with child-birth, does this not suggest that perhaps before becoming mortal, there was a way to do it without all the pain associated with a mortal life?