A stone baby, or lithopedion, results when a fetus dies during an ectopic (typically abdominal) pregnancy, is too large to be reabsorbed by the body, and calcifies. It is not unusual for a lithopedion to remain undiagnosed for decades, and it is often not until a patient is examined for other conditions that a stone baby is found. The oldest reported case is that of a 94 year old woman, whose lithopedion had probably been present for over 60 years.
Lithopedion is a rare phenomenon, occurring once in about 20 000 pregnancies, and with less than three hundred cases noted in medical literature accumulated over some 400 years. Lithopedion may occur from 14 weeks' gestation to full term. The earliest stone baby is one found in an archaeological excavation, dated to 1100 BCE.
A related condition is known as fetus papyraceus, in which the fetus is one of two or more sharing the womb. If the fetus is older than eight weeks at the time of its death, and is retained in the uterus for at least ten weeks, it may undergo mechanical compression such that it takes on a flattened, mummified appearance and resembles parchment paper.
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OBGYN Net =>http://www.obgyn.net/ENGLISH/PUBS/ARTICLES/Stone_Baby.htm
PubMed (enter 'lithopedion' in search box) => http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=Search&DB=PubMed
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