cardinal movements of labour

 Mechanism of labour

A series of changes in position and attitude the fetus undergo during its passage through the birth canal.

Vertex presentation fetus in gynecoid pelvis

Terminology

1. Lie

Longitudinal lie

Transverse lie

Oblique lie

2. Attitude

Posture of fetus

Head flexed over chest

Arms/Hands flexed over chest

Thigh/ legs flexed over abdomen

3. Presentation

Portion of the body of fetus.

Vertex, breech, face, eyebrow, shoulder

4. Position

Fetal presenting part right to left side of maternal birth canal.

5. Denominator

Bony landmark of presenting part, used to describe postion of presentation.

In vertex; occiput

In face; mentum(chin)

In breech; sacrum

In shoulder; scapula

Cardinal movements of labour

Mechanism of labour (9 movements)

1. Engagement

2. Descent

3. Flexion

4. Internal rotation of head

5. Crowning

6. Extension

7. Restitution

8. External rotation of head/ internal rotation of shoulder

9. Lateral flexion of body and shoulder through birth canal

1. Engagement

Biparietal diameter of fetal head passed through pelvic inlet.

In primigrivida; usually occurs 12 hours 

In multigravidae; occurs within 6 hours 

2. Descent

Contraction, maternal pushing effort with contraction of her abdominal muscles.

Baby descents through pelvic inlet towards the pelvic floor.

3. Flexion

Increase flexion of head.

Fetal head come contact with pelvic floor. Allow presenting part of fetus to be sub- occipital bregmatic.

In this position, fetal skull has smallest diameter which assists passage through pelvis.

4. Internal rotation of head

Internal rotation of occiput anteriorly.

5. Crowning

After internal rotation of head  descent occur, maximum diameter of head (biparietal diameter) stretches the vulval outlet.

6. Extension

Fetal head (sinciput, face and chin) sweep over perineum.

Delivery of fetal head by extension.

7. Restitution

Head externally rotates to face of right or left medial thigh of mother.

8. External rotation of head/ internal rotation of shoulder

Head rotates and anterior shoulder reaches pelvic floor and rotate anteriorly. Shoulder lie in anterio- posterio diameter of pelvic outlet.

9. Lateral flexion of body and shoulder through birth canal

After by hook method delivered the anterior shoulder and posterior and delivery of shoulder and trunk by lateral flexion.