Coffin birth, also known as postmortem fetal extrusion,[1][2] is the expulsion of a nonviable fetus through the vaginal opening of the decomposing body of a deceased pregnant woman due to increasing pressure from intra-abdominal gases.
While cases of postmortem fetal expulsion have always been rare, the phenomenon has been recorded under disparate circumstances and is occasionally seen in a modern forensic context when the body of a pregnant woman lies undisturbed and undiscovered for some time following death.
Increasing pressure forces the diffusion of excessive gases into the weakened tissues where they enter the circulatory system and spread to other parts of the body, causing both torso and limbs to become bloated.
[8] It is at this point during the decomposition of a pregnant body that amniotic membranes become stretched and separated, and intra-abdominal gas pressure may force the eversion and prolapse of the uterus,Note b which would result in the expulsion of the fetus through the vaginal canal.
[9] It has been observed that the bodies of multiparous womenNote c are more likely to spontaneously expel the fetus during decomposition than those who died during their first pregnancy, because of the more elastic nature of the cervix.
[11] However, the phenomenon was still recognized by medical science and in 1904, John Whitridge Williams wrote a textbook on obstetric medicine that included a section on "coffin birth".
At autopsy, medical examiners found that both the head and shoulders of the fetus had emerged, and concluded that it was a case of postmortem fetal extrusion in progress.
This was the first forensic case in which it could be concluded that coffin birth had occurred based on the position of the bodies and the clear attachment of the umbilical cord to the un-expelled placenta.
[18] Postmortem fetal extrusion can be very difficult to recognize once a body has undergone complete skeletonization, and bioarchaeologists are often very cautious about asserting the presence of this phenomenon.
[21] A coffin birth was also described in a 2011 episode of the BBC show History Cold Case, featuring the Roman era remains of a woman and three neonates discovered near Baldock, Hertfordshire.
[26] Because postmortem fetal extrusion is so rare, and occurs under highly idiosyncratic conditions regarding the individual and the ambient environment,[3][5][10][19] this phenomenon has not been studied for possible applications to forensic investigation.
At present, forensic scientists have at their disposal an array of established techniques and procedures for a death investigation at the stages of decomposition when postmortem fetal extrusion typically occurs.
[9] In archaeology, the study of mortuary context, that is, the interpretation of the postmortem treatment of the dead, whether an individual or as pertains to patterns within a group, has led to the development of hypotheses on social status and/or hierarchy regarding many cultures, ancient and extant.
In April 2003, the body of Laci Peterson washed up on a shore near San Francisco Bay; she had been pregnant when she disappeared four months earlier, and the fetus she had been carrying was discovered on a separate beach.
Medical examiners later concluded that while Peterson's body was in the bay, the skin over the abdominal cavity had ruptured due to natural decompositional processes.
Tim Flannery wrote that "A rotting whale could fill with gas to bursting, ejecting a fetus the size of a motor vehicle with sufficient force to kill a man.