Components of Labor

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Components of Labor
*The 4 P’s:

• refers to pelvis & soft tissues which include: lower uterine segment, cervix, vaginal canal • 2 pelvic measurements --Necessary to determine adequacy: diagonal conjugate- narrowest at inlet;

transverse diameter- narrowest at outlet
• If disproportion occurs usually the pelvis (If fetus presents in unusual position); could be R/t mother: being < 4’9” tall
being < 18 years old
Underwent pelvic dislocation
• 4 main pelvic types:

1. Gynecoid – round, wide, deeper most suitable (normal female pelvis) for pregnancy 2. Android – heart shape “male pelvis”- anterior part pointed, posterior part shallow 3. Anthropoid – oval, ape like pelvis, oval shape, AP diameter wider transverse narrow 4. Platypelloid – flat AP diameter – narrow, transverse – wider

• Passage of fetal head
• Fetal skull composed of:
8 bones - 2 frontal bones fused; 2 parietal bones; 2 occipital bones; 2 temporal bones. && Where these bones meet become the Suture lines - Sagittal- separates parietal bones; Coronal- separates frontal and parietal; lamboid - separates parietal and occipital. && These suture lines allow for overlapping of bones during delivery Fontanels - anterior (diamond shape); posterior- (triangle) • Smallest diameter-- Smallest diameter is the SUBOCCIPITOBREGMATIC – This area must present to pelvic inlet. ----this is the part you want presenting to pelvis • Engagement- presenting part that enters the pelvis reaches the level of the ischial spines • Molding-- change shape of head produced by force of contractions against cervix- TEMPORARY

• Fetal attitude- degree of flexion the fetus assumes or relation of the fetal parts to one another: ][ (relationship of fetal parts to one another)
complete flexion
moderate flexion
partial flexion
• station- relation of presenting part to the level of the ischial spines: -4 to +4; when the presenting part is level with the ischial spines, it is at station 0 (synonymous with engagement); if it is above the spines it is -1 to -4; if it is below the spines it is +1 to +4; at -4 stations the head is floating; at + 4 station the head is at outlet –aka- crowning.

• Crowning-- Presenting part reaches the perineum; +4 station • Fetal lie-- Relation of fetal long axis to long axis of the mother: Longitudinal (breech, cephalic)
Transverse (shoulder)

• Cephalic- 95%---4 types (longitudinal lie)
Vertex—complete flexion
Brow—poor flexion
Face—poor flexion
Mentum (chin)
• Breech- 3%--3 types (longitudinal lie)
Complete- the baby is in squatting position
Frank—legs are extended, sacrum presents,
Footling—single, double; foot presents
• Transverse- 2% (shoulder) (horizontal lie)

-Relation of presenting part to a specific quadrant of the maternal pelvis; Position is the relationship of the fetal reference point (occiput,mentum,sacrum or acromion process) to one of the four quadrants of the mother’s pelvis. The quadrants are formed by drawing an imaginary line from the mother’s sacral promontory to the upper edge of the symphysis pubis and bisecting it transversely by a line from one side to the other, forming the right anterior and posterior quadrants and the left anterior and posterior quadrants. • 4 parts of fetus used as landmarks

vertex- occiput (o)
Face- mentum (m)
Breech- sacrum (sa)
Shoulder- scapula (A)
• Methods used to determine
Abdominal inspection and palpation
vaginal exam
auscultation FHT’s
• labor is longer if not vertex-- R/t ineffective descent, ineffective dilation, and irregular contraction> increased fatigue, increased risk of c/s, increased risk for lacerations and decreased bonding. • Also places fetus at risk--r/t increased risk of CPD; increased risk for PROM> increased infection;...
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