Getting the heads up: A beginner’s guide to partial unbirthing

In a previous blog, I briefly examined ‘unbirthing’ a fantasy-based sexual paraphilia in which individuals are sexually aroused by the idea of being enveloped and swallowed by a woman’s vagina. This is often termed ‘vaginal vore’ and is commonly viewed as a sub-type of vorarephilia (a sexual paraphilia in which individuals are sexually aroused by the idea of being eaten, eating another person, or observing this process for sexual gratification). While researching the blog on unbirthing, I came across quite a few references to ‘partial unbirthing’. For instance, according to the online Urban Dictionary:

“[Partial unbirthing is the] fetish of an adult head inside a vagina. [The] term was created a few decades ago when the fantasy of unbirthing was broken down into total and partial types with partial unbirthing being the only remotely possible form of the unbirthing fantasy. Even then it is an extremely rare activity and the practice of partial unbirthing, as opposed to the fantasy, is not a form of Vore”.

I had my doubts as to whether partial unbirthing could be anything but a fantasy-based sexual paraphilia until I came across what appear to be actual photographs and videos of the practice online (such as those on the partial unbirthing page of the Encyclopedia Dramatica (ED) website – please be warned that if you click on the hyperlink, the page that opens shows photographs of men with their heads inside female vaginas). In part of an online article on vorarephilia, the Serial Killer Calendar (a surprisingly knowledgeable website on paraphilic behaviours), it noted that partial unbirthing is also known as ‘adult heading’. Looking at the same online photographs as I had looked at, the article claimed “there is controversy about whether it has ever truly happened and disagreements about whether photos of the practice are Photoshop fakes”. The same article also questioned the feasibility of the practice in relation to the restriction of the oxygen supply for the person inserting their head (although this would arguably be an added turn-on for a hypoxyphiliac). The ED article also noted:

“Partial unbirthing (adult head insertion into the vagina) [is a] real practice as opposed to fantasy, it is not a category of ‘vore’. It is only done by sex partners who both find it safe and extremely enjoyable. It is a fetishism that is extremely rare and probably one of the rarest of all human sexual activities. The reason for this is that to be mutually enjoyable and erotic, it requires that the vagina must stretch to enormous size”

I have no evidence to dispute such claims but given the sheer pragmatics involved, the claims don’t seem unreasonable. One of the more in-depth articles on partial unbirthing can be found on the Wikibin (WB) website. It also claims that the activity is (unsurprisingly) “extremely uncommon” and “much more common as a pure fantasy than in actuality”. The WB article also claims that there have been attempts (but it doesn’t say by who or what) to sub-classify partial unbirthing under a new category called ‘endosomatophilia’. The article estimated that less than one in a million sexual partners have actually engaged in partial unbirthing (although personally I think this figure is still too high). The article also claims that it is mutually enjoyable and erotic for couples that engage in the practice:

“It requires that the vagina must stretch to enormous size. This requires a consenting, cooperative, and extended effort between the sexual partners, with both partners considering the same fetish to be erotic…This of course is only possible where the woman has an extremely huge opening of her pelvis. Such a huge or Justo Major Pelvis is also called ‘Giant Pelvis’. This condition is where the minimum pelvis size is enlarged uniformly in every direction by a linear factor of 1.5, or more than the average 11-inch wide pelvis. This 16.5-inch ‘or more’ Justo Major pelvic width is a condition that is only present in less than one in a thousand adult women”.

The article also claims that some normal sized women sometimes stretch their vaginas to facilitate orgasmic stimulation. This is sometimes as a consequence of the woman having a “fullness fetish” that according to the article is also known as a ‘bulk intromission’ fetish (I’ve tried to look for further information on this fetish but have not yet found anything). Although this would appear to be exceedingly rare, the WB article says that with “gradual repeated stretching they occasionally stretch almost to the walls of their pelvic bone opening” to the size of a newborn baby’s head.

There is still the fundamental issue of whether partial unbirthing is humanly possible. A number of partial unbirthing articles all carry exactly the same text about an alleged study that I have been unable to track down. The verbatim text used in most of these articles claims that:

“A well known government Hispanic study included the anthropometry (scientific measurement) of nearly 5000 adult women using anthropometric calipers to measure the largest pelvis at 19 inches bi-iliac width (side-to-side bone width). This made her 19-inch wide Justo Major pelvis have a huge 1.73 ratio when compared to the average size pelvis of only 11 inches width. This was even a larger size pelvis than a pelvis of ‘minimum’ Justo Major size (that requires at least a 1.5 ratio). If a woman with a pelvis of this very large size were to do the same vaginal stretching practice to near her bone opening size, she could then vaginally take inside her vagina a huge 24-inch adult head. That size head would be 24 minus 21 inches, or 3 inches, larger than the 21-inch circumference adult head that a pelvis of the minimum 1.5 ratio Justo Major size pelvis could potentially stretch around. This larger size 19-inch wide pelvis would require a lesser degree of stretching to be comfortable when taking inside a 21-inch (much smaller size) adult head. This degree of comfort might be comparable to a woman of average size being vaginally double fisted by hands of considerably smaller size, or even being fisted by just one large hand. This less common but larger size pelvis (one in five thousand) Justo Major pelvis would have a sufficient size to potentially make partial unbirthing much easier to achieve”. 

There is no academic or clinical research on partial unbirthing fetishes although I did come across a small unscientific poll on the Deviant Art website. The poll asked its clientele of self-admitted ‘sexual deviants’ what the strangest fetish was and 16% of the sample said partial unbirthing was the strangest. Unbirthing topped the poll (22%), followed by neophilia (18%; having sexual intercourse with baby children), and furry infantilism (11%; a form of paraphilic infantilism among the Furry Fandom in which adults pretend to be baby animals). Other strangest fetishes included cement fetishes (8%), necrofurs (5%; Furry fandom necrophilia), vorarephilia (5%), and zoophilia (3%).

After reviewing the scant anecdotal evidence I am convinced that that partial unbirthing fetishes exist at the very least in fantasy form and there are certainly examples of online fictional fantasy stories involving partial unbirthing. However, I remain ambivalent as to whether the practice can be achieved in actuality. The evidence (such that it is) suggests it is theoretically possible but whether there are genuinely recorded cases is suspect at best.

Dr Mark Griffiths, Professor of Gambling Studies, International Gaming Research Unit, Nottingham Trent University, Nottingham, UK

Further reading

Encyclopedia Dramatica (2011). Partial unbirthing. May 25. Located at:

Serial Killer Calendar (2012). Vorarephilia. Located at:

Urban Dictionary (2012). Partial unbirthing. Located at:

Wikibin (2012). Partial unbirthing fetishism. Located at:

Wikipedia (2012). Pelvis justo major. Located at:

About drmarkgriffiths

Professor MARK GRIFFITHS, BSc, PhD, CPsychol, PGDipHE, FBPsS, FRSA, AcSS. Dr. Mark Griffiths is a Chartered Psychologist and Distinguished Professor of Behavioural Addiction at the Nottingham Trent University, and Director of the International Gaming Research Unit. He is internationally known for his work into gambling and gaming addictions and has won many awards including the American 1994 John Rosecrance Research Prize for “outstanding scholarly contributions to the field of gambling research”, the 1998 European CELEJ Prize for best paper on gambling, the 2003 Canadian International Excellence Award for “outstanding contributions to the prevention of problem gambling and the practice of responsible gambling” and a North American 2006 Lifetime Achievement Award For Contributions To The Field Of Youth Gambling “in recognition of his dedication, leadership, and pioneering contributions to the field of youth gambling”. In 2013, he was given the Lifetime Research Award from the US National Council on Problem Gambling. He has published over 800 research papers, five books, over 150 book chapters, and over 1500 other articles. He has served on numerous national and international committees (e.g. BPS Council, BPS Social Psychology Section, Society for the Study of Gambling, Gamblers Anonymous General Services Board, National Council on Gambling etc.) and is a former National Chair of Gamcare. He also does a lot of freelance journalism and has appeared on over 3500 radio and television programmes since 1988. In 2004 he was awarded the Joseph Lister Prize for Social Sciences by the British Association for the Advancement of Science for being one of the UK’s “outstanding scientific communicators”. His awards also include the 2006 Excellence in the Teaching of Psychology Award by the British Psychological Society and the British Psychological Society Fellowship Award for “exceptional contributions to psychology”.

Posted on July 22, 2013, in Case Studies, Gender differences, Paraphilia, Psychology, Sex and tagged , , , , , , , , , , . Bookmark the permalink. Leave a comment.

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