Active breech birth: the point of least resistance.

In March 2006 I attended the first international Breech Birth Conference in Vancouver, Canada, which gathered together midwives, medical practitioners and researchers to discuss such issues as research, safety and techniques used during vaginal breech birth. Presenters came from eight different countries--Canada, Germany, Norway, Belgium, United Kingdom, Netherlands, Australia and New Zealand. It was a valuable time of exchanging ideas and heartening to meet other supporters of vaginal breech birth equally committed to growing and maintaining the skills necessary to support women during the experience. The multi-disciplinary programme meant accessibility to different approaches as well as an international flavour.

One workshop I attended was on symphysiotomy --the surgical division of the fibro cartilaginous symphysis pubis and its reinforcing ligaments by way of a scalpel blade through the mons pubis. This technique is an obstetric strategy to allow birth of the often dreaded--but rarely occurring --head entrapment of the breech baby. The workshop presenter noted this occurs probably once in every five hundred breech births when cephalo-pelvic disproportion has been excluded (Menticoglou, 2006). Gruesome you may say --but it was actually very affirming for me as it re-emphasised the importance that the woman's position plays for giving birth to her breech baby to avoid what I term 'bed dystocia'.

Bed dystocia occurs when the baby's progress is halted due to, firstly, reduction of the woman's lumbar spine curvature (lordosis), secondly, the backward tilting of the pelvis and, thirdly, entrapment of the sacrum by maternal weight, all of which can occur if the woman is lying on a firm bed. These changes mean the brim of the woman's pelvis is less accessible to the baby's after-coming head (or shoulders in cephalic presentation), most particularly, if the woman is in the stranded beetle position (lithotomy). Equally, the antero-posterior diameter of the woman's pelvic outlet is reduced as her sacrum is hampered in moving outwards.

The iatrogenic cause of, and corrective strategies for, bed dystocia have clearly been demonstrated by Gherman and others. Their radiological examination of pelvic diameters of women at least 37 weeks pregnant, studied the dorsal lithotomy position as well as during the McRoberts' manoeuvre (hyper flexion of the woman's legs onto her chest). The authors note "McRoberts' manoeuvre does not change the actual dimensions of the maternal pelvis, it straightens the sacrum relative to the lumbar spine, with a cephalic rotation of the symphysis pubis sliding over the fetal shoulder" (Gherman, Tramont, Muffley & Goodley, 2000, p45). Thus the manoeuvre is a correctional technique used to release the entrapped sacrum held by the woman's weight on the obstetric bed.

Russell's 1969 study of pelvic x-rays of 96 women in the last trimester of pregnancy in both the dorsal and sitting positions identified the gains that can be made to increase all pelvic diameters by positional changes (Russell, 1969). Further, the 'primitive' birthing positions such as upright positions with the hips abducted--as in a supported squat--"considerably increases the outlet measurement of the pelvis" (Russell, 1982, p712). Equally, the forward tilting of the pelvis slides the innominate bones forward and down to increase the anterior-posterior diameter of the inlet. This tilting forward of the pelvis is a movement an active breech birthing woman intuitively takes as she pokes out her buttocks. Depending on when she does it, this can effectively help the baby's head into the pelvic brim, roll the baby's head down into the posterior space or precipitate the action of the face sweeping over the perineum as the pubic arch acts as a fulcrum for the baby's head (Banks, 1998).

The 28 percent increase in the pelvic outlet--1cm in the transverse diameter and 2cm in the anteroposterior diameter (Russell, 1982) of active birthing is greater than that which is normally achieved by symphysiotomy, which, primarily, increases the transverse diameters by 1cm (Menticoglou, 1990). While medicine describes symphysiotomy as part of "the obstetric arsenal" (Bjorklund, 2002), women giving birth to their breech babies can feel comforted that the midwifery approach of utilising active birthing positions will not wage war on their bodies and impede their babies' descent. Instead it facilitates breech birth with both woman and baby as active participants to optimise maternal pelvic diameters and the birth of the baby's after-coming head.

References

Banks, M. (1998). Breech Birth Woman-Wise. Birthspirit: Hamilton. For a photographic example of this last action in progress, see page 81.

Bjorklund, K. (2002). Minimally invasive surgery for obstructed labour: symphysiotomy during the twentieth century (including 5000 cases). BJOG: an International Journal of Obstetrics and Gynaecology, 109, 236-248.

Gherman, R.B., Tramont, J., Muffley, & Goodley, T.M. (2000). Analysis of McRoberts' manoeuvre by X-ray pelvimetry. Obstetrics & Gynaecology, 95(1), 43-47.

Menticoglou S. (1990). Symphysiotomy for the trapped after coming parts of the breech: A review of the literature and a plea for its use. The Australian & New Zealand Journal of Obstetrics & Gynaecology, 30 (1), 1-9.

Menticoglou, S. (2006). Workshop D: Symphysiotomy in the management of entrapment of the after coming head, Breech Birth Conference: International Perspectives on the Management of Term Breech Pregnancies and Birth, 20-21 March 2006, Vancouver, British Columbia, Canada.

Russell, J.G.B. (1969). Moulding of the pelvic outlet. Journal of Obstetrics & Gynaecology of the British Commonwealth, 76, 817-820.

Russell, J.G.B. (1982). The rationale of primitive delivery positions. BJOG: An International Journal of Obstetrics & Gynaecology, 89 (9), 712-715.

Maggie was our very first contributor to this column in October 2003. In this issue she writes on the topic for which, I can confidently say, she is most famous amongst midwives. Any comments you care to make can be made to Maggie directly at [e-mail] or to the interim editor Rhondda Davies: [e-mail]

Maggie Banks, Home Birth Midwife.