Even in sorrow we rejoice in the coming of the Lord, knowing that our sorrow will be turned to joy, a joy that cannot be turned back into sorrow. That promise does not undo our pain or sorrow, but we rejoice in the promise that we will cease to sorrow.
The woman in childbirth genuinely suffers pain, but she will forget it. Time and the joy of her child dulls her recollection, sometimes even to the point of its disappearance. Through the grace of God we too are giving birth, to new selves. Some will suffer more than others in their labor pains, but all who give birth will rejoice in what is born.
Mosiah 3:3-5: Awake, and hear the words which I shall tell thee; for behold, I am come to declare unto you the glad tidings of great joy. For the Lord hath heard thy prayers, and hath judged of thy righteousness, and hath sent me to declare unto thee that thou mayest rejoice; and that thou mayest declare unto thy people, that they may also be filled with joy. For behold, the time cometh, and is not far distant, that with power, the Lord Omnipotent who reigneth, who was, and is from all eternity to all eternity, shall come down from heaven among the children of men . . . .
God has come among us. He will come again. We remember and rejoice.