Antenatal perineal massage
(APM) or birth canal widening (BCW) is the massage of a pregnant woman’s perineum around the opening to the vagina, performed anywhere in the 4 to 6 weeks before childbirth and usually on 4-6 separate occasions. The practice aims to more gently mimic the massaging action of a baby’s head on the opening to the birth canal prior to birth, which enables some of the hard work of labour to be done before the start of labour. The intention is to attempt to prevent tearing of the perineum during birth, and reduce the need for an episiotomy or an instrument (forceps or vacuum extraction) delivery.
The goal of APM is to prevent the baby’s head from undergoing excessive strain during the last 30 minutes of labour. It seeks to train the mother to relax her pelvic floor to allow the baby’s head to pass through the opening, to stretch the two fibrous layers within the Uro-Genital Membrane, a triangular shaped muscular shelf at the front half of the opening of the bony pelvis, through which the 2 cm diameter birth canal and urethra pass, and to transform the fat packed rigid skin at the opening to the birth canal into paper thin stretchy elastic skin, all without using the baby’s head.
If the external skin (perineal skin) opening has been stretched before birth, to 10 cm, then there is no reason to perform an episiotomy to increase the diameter of the opening of the birth canal. Tearing is less likely as the external skin at the opening has been stretched already and is lax, whilst the underlying muscular pelvic floor has not been damaged. Episiotomy permanently damages the pelvic floor muscle, as the episiotomy cuts through the nerve supply to this muscle, so the larger part of the pelvic floor muscles atrophies and becomes replaced by scar tissue, increasing the mother’s chance of developing a prolapse in the future. Antenatal Perineal Massage does not damage the pelvic floor, so protects against a prolapse.
Antenatal Perineal Massage affords mothers worldwide, irrespective of income, the opportunity to shorten the critical last 30 minutes of labour. Mothers with a narrowed opening in their bony pelvis, whether from being born with an abnormally narrow pelvis, from previous fracture or from deformity secondary to infection in the bone (osteomyelitis), may need surgical intervention, as indicated by a failure to progress either when the baby’s head fails to enter the bony pelvis or develops fetal distress.