This qualitative study evaluates the acceptability of positioning pregnant women in labour in an optimized position, which consists in the hyperflexion of the legs and the loss of the lumbar lordosis. Twenty patients in situation of dystocia will adopt the described position for a limited amount of time.

Recent data brings out that the Caesarian Section rate in Switzerland is quite high, reaching 33.4 %. Though, the reasons to this increasing amount of CS are not fully known. Therefore, it is absolutely necessary to expand the existing knowledge in different fields, including the biomechanics of childbirth. Numerous CS are performed in response to an obstructed labour, especially when the foetus does not engage in the pelvis near full dilatation. In order to manage such situations, midwifes currently position parturients in pragmatic postures. Although not verified by data, this care management suggests that it is possible to impact the position of the bone segments at stake for vaginal birth including pelvis and lumbar spine and to promote the descent of the foetus through the pelvic inlet plane. In his PhD thesis about vaginal birth biomechanics, Desseauve et al investigated this area and found out that an optimized position similar to the squatting position (hyperflexion of the thighs and loss of the lumbar lordosis) could be close to the perfect delivery position in terms of ability for the foetus to go through the pelvic inlet plane. Although these findings are encouraging, it is yet to be confirmed in clinical practice, particularly when a dystocia occurs. Prior to doing that, it is though necessary to validate the optimized posture in terms of acceptability in a qualitative clinical study. In this study, fifteen to twenty parturients who respond to the inclusion criteria and whose foetus does not engage in the pelvis near full dilation will be asked to adopt the optimized position for a twenty minutes period. The investigator will then consign information reflecting the progress of the labour on a data sheet.

Inclusion Criteria:

• Informed consent as documented by signature
• Parturient in situation of mechanical dystocia (non engagement at full dilation)

Exclusion Criteria:

• Inability or medical contraindications to undergo the investigated intervention (e.g. orthopaedic injury or disease preventing the parturient from adopting the optimised position)
• Clinically significant concomitant diseases
• Incapacity of judgment
• Inability to follow the procedures of the study due to language problems, psychological disorders, dementia, etc.
• Foetus cardiac rhythm disorder