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Factors Affecting Labor

Fetal Head Size- cephalopelvic disproportion (CPD) baby's head or body is too large to fit through the mother’s pelvis. 

Attitude-relationship of the fetal body parts to one and other (degree of flexion)

 Complete Flexion-most common; "the fetal position"; vertex presentation; chin touches the chest

 Moderate Flexion-second most common; "military position"; sinciput presentation; chin does not touch the chest

 Partial Extension-uncommon; brow presentation; can make birth difficult

 Complete Extension-relatively rare; face presentation; the occiput touches the fetuses upper back

Lie-relationship of the fetal spine to the maternal spine

Position-relationship of the presenting part of the fetus to a specific quadrant of the mother's pelvis First Letter -which way the presenting part is facing

 Second Letter -the presenting part of the fetus

 Third Letter -which way the presenting part is lying in relation to maternal pelvis

Transverse Lie

 fetal spine is 90° to maternal spine

 fetuses line horizontally

Longitudinal Lie

 fetal spine is parallel to maternal spine

 fetuses line vertically

 can be both cephalic or breach

 most common, about 99%

Oblique Lie

 fetal spine is 45° to maternal spine

 midway between longitudinal and trans

 rare and considered abnormal

Right Occipitposterior

Right Occipitanterior

 Most common

 Duration of L&D shortest

Left Occipitposterior

 Labor tends to be longer and more

painful

Left Occipitanterior

 Most common

 Duration of L&D shortest

Passenger:

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Presentation-the part of the fetus that presents into the birth canal first. Determine by attitude, lie, and position.

Cephalic Fetal Presentation:

Vertex

 parietal bones of the presenting part

of the fetus

 considered optimal for fetal descent

 longitudinal lie with complete flexionattitude

Brow & Sinciput

 Brow or forehead is the presenting part of the f

  longitudinal lie with moderate flexion attitude

Face

 face is the presenting part of the

fetus

  longitudinal lie with partial

extension attitude

 severe edema and facial distortionoccur from pressure of uterine

contractions

Mentum

 chin is the presenting part of the fetus

  longitudinal lie with partial extension

attitude

 severe edema and facial distortion occu

from pressure of uterine contractions

 vaginal delivery is usually impossible

Breech Fetal Presentation:

Complete

 buttocks and feet are the

presenting part of the fetus

  longitudinal lie with complete

flexion attitude  legs are crossed

  least difficult breech position

Frank

 buttocks are the presenting part of the

  longitudinal lie with moderate flexion

attitude

 both legs are drawn up

Footling

Incomplete & Footling

 One or both of the knees and legs are the presenting part of the fetus

  longitudinal lie

  legs are extended with little or no hip flexion

 most difficult breech position

 cord prolapsed is common

Other Fetal Presentation:

Compound

 Extremity presents with

another major presenting

part (usually head)

 They present simultaneou

Shoulder

 Shoulder, iliac crest, hand or elbow is the

presenting part

 Transverse lie

 Ranges from complete flexion to complete

extension

 In mulitparous it can be caused due to relaxation

of the abdominal walls

 Other causes: pelvic contraction, placenta previa