Pelvis justo major

Pelvis justo major (also called "giant pelvis") is a rare condition of the adult female pelvis where the pelvis flares above the iliopectineal line.^[1] It is 1.5 or more times larger than an average pelvis in every direction and is typically at least 42cm (16.5 inches) in biiliac width. Even though this condition is classified as a congenital abnormality, it is not normally considered a medical disease of the pelvis as it typically holds a true gynecoid shape, only larger, without posing other major health risks except in childbirth.

Pregnant women with this condition, at the time of delivery, may have a precipitous birth.^[2] With a wider justo major pelvis, there is no pelvic bone "molding" of the fetal head as is typical for a normally sized pelvis, and as such there is virtually no resistance from the pelvis itself.^[3] As this allows for a much more rapid vaginal birth, there is an increased risk of tearing of the perineal soft tissues.^{[citation needed]} At the time of delivery, the strong uterine contractions and maternal bearing down almost instantly overwhelm the integrity of a previously unstreched vaginal orifice. This is often the case if the women have not previously practiced vaginal stretching to the degree that allows such an instant birthing, especially so for a primiparous woman. This "instant delivery" problem leads many OBGYN doctors to stress the importance of women with a larger pelvis, especially those with Pelvis justo major, practicing pre-delivery vaginal stretching to avoid perineal injury.^{[citation needed]}

Pelvis justo major is present in less than one in one thousand adult women, and a measurement scan or anthropometry by calipers is required to diagnose the condition.^{[citation needed]} The incidence of pelvis justo major pelvis is not found to be a strictly standard deviation type variation, as it follows a tail skewed deviation to the right. Pelvis justo major is classified as congenital and thought to be partially inherited, especially from the maternal side.^{[citation needed]}