The unborn child of Richard Rahl and Kahlan Amnell died only weeks after conception when Kahlan was brutally attacked by a gang of thugs in Anderith. The child was conceived on its parents' wedding night at the end of Temple of the Winds and was only known to exist in the final chapters of Soul of the Fire. Due to the Chimes being released, the magic of the amulet given to Kahlan by Shota would have no effect, thusly, allowing the conception of the child.
Kahlan struggled with the knowledge that she was with child, and the trouble that would come because of it. She informed Du Chaillu that she was pregnant and that she'd prefer if Richard wasn't told. She had planned to visit a local mid-wife in hopes to obtain a potion to terminate the pregnancy. However, upon opening the vial and readying herself to drink it, she had a change of heart and decided she couldn't possibly kill her husband's child.
Following this, Kahlan went off on her own, pondering her decision and was then attacked by a group of messengers sent by Dalton Campbell. She was beaten nearly to death and beyond recognition as even Richard was unable to recognize her. When he did, however, their child had been killed before Du Chaillu went against Kahlan's wishes and told him that he was to become a father.
During Kahlan's recovery back in Westland, she often forgot that she had lost the baby, giving Richard the painful task of reminding her.
Should the child have been a girl, she would most likely be an extremely powerful Confessor with free control of the Con Dar, as well as a sorceress with both sides of the gift and ability with prophecy (therefore, possibly a witch woman). If the child had been a boy, he would further be a male Confessor, a war wizard, possibly a prophet, and the inheritor of the Lord Rahl bond.