Lithopedions, or "Stone Babies"

A lithopedion, or "stone baby" is a rare condition when a fetus dies during an ectopic pregnancy and is too large to be reabsorbed into the mother's body. The body, instead, calcifies the fetus, protecting the mother form infection. In many cases, the lithopedion remains in the mother's body, and she may go on to have healthy pregnancies.

From the article:

"The skilled surgeons, Claude le Noir and Iehan Couttas, cut into Madame Charti's body and saw a large growth in her stomach. They broke their razors trying to penetrate the tumor, so they attacked it with mauls and drills. Finally they cracked open the stone and saw inside the head and shoulder of a child.

Excited by their discovery, the surgeons called in other physicians and continued to tear away at the calcified remains with iron tongs. In his book The Two-Headed Boy, Jan Bondeson describes the tumor as hard, "wrinkled and formed like a turkey's crest." The child within it looked like this: "The right arm extended down toward the navel; its hand had been broken off through carelessness when the stone-child was extracted. The bones of the head were transparent and the fontanelles were not closed. In several places the skin of the head was covered with hair. The stone-child had one sole tooth, situated in the lower jaw"."

Lithopedians may occur due to a number of tragic or fateful events. Perhaps a pregnant woman made a narrow escape from a petrifying creature such as a basilisk or cockatrice, but her unborn child was not so fortunate.  Likewise, a curse by a witch or other nasty individual could render the fetus as stone.

Natural birth of the now-petrified child is highly unlikely, and the fetus requires removal by magical means, rough cesarean surgery, or physical removal after the tragic death of the mother.

The stone baby may provide powerful, yet tragic, enchantment.

Its primary use is as a material component for enchanted items and devices. While other, more easily obtained components may be more in favor, the lithopedian, by nature of its petrification within the living body of its mother, eliminates the need for any other components, and amplifies the intended effect.

• For devices providing protection against petrification, such as potions or rings, a sliver or bit of powdered lithopedian grants an additional +2 to saves
• wand of petrification (flesh to stone)  - -2 save penalty
• Stone golem - Speeds Golem to move = 9 (S&W), +2 magic weapons required to hit.
• Stone guardian golem - if the control ring incorporates a bit of lithopedian, the ring may link up to four guardians.

Laying on of a lithopedian, along with application of cure disase will reverse the petrification of an unfortunate fetus, thus preventing the tragedy from reoccurring...