Illustration of a female pelvis showing a foetus that is in the shoulder presentation position during labour, or childbirth, with a prolapsed arm. A hand inserted through the vagina (birth canal) to the uterus (womb) is attempting to rotate the baby. This presentation often results in a difficult labour that leads to the death of the foetus and endangers the life of the mother. In modern times this foetus would be delivered by a Caesarean section. From An Improved System of Midwifery, by Wooster Beach (1794-1868), published in 1851.