The Labor Process

The Labor Process

n Labor is the series of events by which uterine contractions and abdominal pressure expel the fetus and placenta from the woman’s body.

n Regular contractions cause progressive dilatation of the cervix and sufficient muscular force to allow the baby to be pushed to the outside.

n A time of change, both ending and beginning for the woman, fetus and family.

n Woman uses all psychological and physical coping methods.

Nursing Process

n Assessment

n Outcome Identification and Planning

n Implementation

n Outcome Evaluation

Theories of Labor Onset

n Unknown

n Factors:

n Uterine muscle stretching releases prostaglandin's.

n Pressure on cervix stimulates release of oxytocin from posterior pituitary.

n Oxytocin stimulation, works together with prostaglandin to initiate contractions.

n Increasing estrogen in relation to progesterone stimulates contractions.

n Placental age, triggers contractions at a set point.

n Rising fetal cortisol levels, reduce progesterone formation and increase prostaglandin formation.

n Fetal membrane production of prostaglandin which stimulates contractions

n Seasonal and time influences.

Signs of Labor

n Preliminary Signs of Labor:

n Before labor, the woman experiences subtle signs of labor. Teach how to recognize these.

n Lightening-descent of fetal presenting part into the pelvis.

n Occurs 10 to 14 days before labor begins.

n Shooting leg pains, increased vaginal discharge, urinary frequency.

n Increase in Level of Activity:

n Feeling full of energy due to increase in epinephrine release initiated by decreased progesterone produced by placenta.

n Braxton Hicks Contractions:

n Stronger 1 week to days before labor.

n Support if not true contractions.

n Ripening of the Cervix:

n Internal sign seen with pelvic exam.

n Cervix is butter-soft and tips forward.

Signs of True Labor

n Uterine and cervical changes.

n Uterine Contractions:

n Surest sign that labor has begun.

n Effective, productive, involuntary uterine contractions.

n Show or Bloody Show:

n Blood mixed with mucus when the mucus plug is expelled.

n Pink tinged.

n Rupture of the Membranes:

n Either sudden gush or scanty, slow seeping of clear fluid from the vagina.

n Amniotic fluid continues to be produced until delivery of the membranes.

n Early rupture is good, fetal head settles snugly into the pelvis.

n Risks: infection and cord prolapse.

n Induce after 24 hours.

Components of Labor

n Four integrated concepts:

n Passage

n Passenger

n Power of labor

n Psyche of the woman is preserved.

n 1. Passage:

n Route the fetus must travel from uterus through cervix and vagina to external perineum.

n Diagonal conjugate-anterior-posterior diameter of the inlet.

n Transverse diameter of the outlet.

n Pelvis structure at fault or fetal head is presented to the birth canal at a less than its narrowest diameter, not because the head is to large. Avoid negative thoughts about the baby.

n 2. Passenger:

n Fetus is the passenger and must pass through the pelvic ring.

n Depends on fetal skull and alignment with the pelvis.

n Structure of the Fetal Skull:

n Cranium-upper portion of skull

n 4 superior bones-fontal, 2 parietal, and occipital are important in childbirth.

n 4 at base of cranium-sphenoid bone, ethmoid bone and 2 temporal bones.

n Chin-mentum can be a presenting part.

n Suture lines allow cranial bones to move and overlap, thus molding or diminishing the size of the skull so it can pass through the birth canal.

n Fontanelles are membrane-covered spaces found at junction of the main suture lines.

n Compress during birth to aid in molding of the fetal head.

n Anterior fontanelle (bregma) lies a the junction of the coronal and sagittal sutures.

n Diamond shaped

n Anteroposterior diameter-3 to 4 cm.

n Transverse diameter-2 to 3 cm.

n Posterior fontanelle-lies at junction of lambdoidal and sagittal sutures.

n Triangular shape

n 2 cm. across widest part.

n Vertex-space between the two fontanelles

n Diameters of the Fetal Skull:

n Shape is wider anteroposterior than its transverse diameter.

n Fetus must present transverse diameter to the smaller diameter of the maternal pelvis.

n Biparital diameter-9.25 cm.

n Outlet space-9.5 to 11.5 cm.

n Engagement – setting of fetal head into the pelvis.

n Depends on degree of flexion of fetal head.

n Inlet-12.4 to 13.5 cm.

n Molding:

n Change in shape of the fetal skull produced by the force of uterine contractions pressing the vertex against the not yet dilated cervix.

n Overlap and cause head to become narrower but longer.

n Lasts 1 to 2 days not permanent.

n No skull molding occurs when fetus is breech; buttocks are first.

n Fetal Presentation and Position:

n Attitude-degree of flexion the fetus assumes during labor or relation of the fetal parts to each other.

n Good attitude-complete flexion:

n Spinal column bowed forward

n Head flexed forward-chin touches the sternum

n Arms flexed and folded on chest

n Thighs flexed onto abdomen and calves pressed against posterior aspect of thighs

n Ovoid shape

n Moderate flexion-military position-chin not touching the chest.

n Partial extension-brow of head presents first.

n Engagement – settling of presenting part of fetus far enough into pelvis to be at level of ischial spines, at midpoint of pelvis.

n Floating-a presenting part not engaged.

n Dipping-a presenting part that is descending but not yet reached iliac spines

n Assessed by vaginal and cervical exam.

n Station:

n Relationship of presenting part of fetus to level of ischial spines

n Station 0 - presenting part at level of ischial spines (head is engaged).

n Minus station – presenting part above the spines (-1cm to - 4cm) (floating).

n Plus station – presenting part is below the spines (+1cm to +4cm) at +3 to +4 station presenting part is at perineum and can be seen if vulva is separated (crowning).

n Fetal Lie:

n Lie is relationship between long axis of fetal body and long axis of woman’s body.

n 99% are longitudinal lie.

n Types of Fetal Presentation:

n Demotes the body part that will first contact the cervix or deliver first. Determined by fetal lie and degree of flexion (attitude).

n Cephalic presentation-head is the fetal part that first contacts the cervix.

n Four types:

n Vertex-best

n Brow

n Face

n Mentum

n Caput succedaneum-edematous area of fetal skull that contacted the cervix during labor.

n Breech Presentation:

n Buttocks or feet are the first body part to contact the cervix.

n 3% of births

n Affected by attitude

n Types:

n Complete

n Frank

n Footling

n Shoulder Presentation:

n Transverse lie, fetus is lying horizontally in the pelvis so long axis is perpendicular to mother.

n Presenting part-shoulders, iliac crest, hand or elbow.

n Fewer than 1%

n Cesarean birth

n Types of Fetal Position:

n Relationship of presenting part to a specific quadrant of the woman’s pelvis.

n Pelvis is divided into 4 quadrants according to the mother’s right and left.

n 1. Right anterior

n 2. Left anterior

n 3. Right posterior

n 4. Left posterior

n Abbreviations: (3 letters)

n Middle letter denotes fetal landmark: O for occiput, M for mentum or chin, SA for sacrum, A for acromion process.

n First letter defines whether the landmark is pointing to the mother’s right R or left L.

n Last letter defines whether the landmark points anteriorly A, posteriorly P, or transversely T.

n LOA-left occipitanterior- most common.

n ROP-right occipitoposterior-second

n Six common positions

n Position influences the process and efficiency of labor.

n Fastest-ROA or LOA

n Extended-ROP or LOP-more painful

n Importance of Determining Fetal Presentation and Presentation:

n Presentations other than vertex puts the fetus at risk.

n Implies proportional differences between fetus and pelvis.

n Methods to determine position, presentation and lie:

n 1. Abdominal inspection and palpation

n 2. Vaginal exam

n 3. Auscultation of fetal heart tones

n 4. Sonography

n Mechanisms of Labor (Cardinal Movements)

n A number of different position changes to keep the smallest diameter of fetal head presenting to the smallest diameter of the birth canal.

n Descent

n Downward movement of biparietal diameter of fetal head to within pelvic inlet.

n Flexion

n Fetal head bends forward onto chest.

n Suboccipitobregmatic diameter.

n Internal Rotation

n Head flexes as it touches pelvic floor, and occiput rotates until it is superior or just below the symphysis pubis, bringing head into best diameter for the outlet of pelvis.

n Brings shoulders into position to enter the inlet.

n Extension

n As occiput is born, back of neck stops beneath the pubic arch and acts as a pivot for the rest of the head.

n Head extends and foremost parts of head, face and chin are born.

n External Rotation

n Immediately after head of infant is born

n Head rotates from anteroposterior position back to diagonal or transverse position of the early part of labor.

n Anterior shoulder is born first, assisted by downward flexion of infant’s head.

n Expulsion

n Once shoulders are born, the rest of the baby is born easily and smoothly.

n End of the pelvic division of labor.

n Supplied by the fundus of the uterus.

n Implemented by uterine contractions

n A process that causes cervical dilatation

n Then expulsion

n After full dilatation of cervix power is abdominal muscles.

n Do not bear down with abdominal muscles until cervix is fully dilated. Could cause fetal and cervical damage.

n Uterine Contractions:

n Origin:

n Begin at a pacemaker point located in the myometrium near one of the uterotubal junctions.

n Each contraction begins at that point and then sweeps down over the uterus as a wave

n After a short rest period another contraction is initiated.

n In early labor, pacemaker is not synchronous

n Pacemaker becomes more attuned to calcium concentration in myometrium and begins to function smoothly.

n Phases

n 1. Increment-when intensity of contraction increases.

n 2. Acme-when the contraction is at its strongest.

n 3. Decrement-when intensity decreases.

n Between contractions the uterus rests 10 min.early labor, 2 to 3 min. later.

n Duration increasing from 20 to 30 seconds to a range of 60 to 90 seconds.

n Contour Changes

n Upper-becomes thicker and active, preparing to exert strength to expel fetus.

n Lower segment-becomes thin-walled, supple, and passive so it can be pushed out.

n Physiologic retraction ring-ridge on inner uterine surface.

n Contour changes to elongated.

n Pathologic retraction ring (Bandl’s ring)-abdominal indentation that is a danger sign of impending rupture of lower uterine segment.

n Cervical Changes:

n Effacement-shortening and thinning of the cervical canal (normal 1 to 2 cm.)

n Dilatation-enlargement of cervical canal from a few millimeters to 10 cm.

n Increases diameter of cervical canal lumen by pulling cervix up over presenting part.

n Fluid filled membranes press against cervix.

n Psyche

n Psychological state or feelings that women bring into labor with them.

n Fright, apprehension,excitement, awe.

n Debriefing time.

Stages of Labor

n Divided into 3 stages:

n First stage of dilatation-beginning with true labor contractions and ending with cervix fully dilated.

n Second stage-from time of full dilatation until the infant is born.

n Third or placental stage-from the time the infant is born until after delivery of the placenta.

n Fourth stage-first 1 to 4 hours after birth of the placenta.

First Stage of Labor

n Divided into 3 phases:

n 1. Latent

n 2. Active

n 3. Transition

n Latent phase:

n Preparatory phase-begins at the onset of regularly perceived uterine contractions and ends when rapid cervical dilation begins.

n Contractions-mild and short 20 to 40 sec.

n Cervical effacement occurs

n Cervix dilates from 0 to 3 cm

n Phase lasts approx. 6 hours in nullipara and 4.5 hours in multipara.

n Analgesics given too early in labor will prolong this phase.

n Walking, preparation for birth, packing, care for siblings.

n Active phase:

n Cervical dilatation occurs more rapidly, from 4 cm to 7 cm.

n Contractions are stronger, lasting from 40 to 60 sec., every 3 to 5 min.

n Phase lasts from 3 hours in nullipara to 2 hours in multipara.

n Show and rupture of membranes may occur.

n True discomfort.

n Dilatation 3.5 cm in nullipara per hour to 5 to 9 cm in multipara per hour.

n Analgesics has little effect on progress of labor.

n Transition Phase:

n Dilatation 8 to 10 cm occur

n Contractions at peak of intensity every 2 to 3 min. with duration of 60 to 90 sec.

n If membranes not ruptured, will rupture at 10 cm.

n If not occurred-show will be present and mucus plug is released.

First Stage of Labor

n Full dilatation and complete cervical effacement occur.

n Intense discomfort and nausea/vomiting, feeling of loss of control, anxiety, panic, irritability.

n Her focus is inward on task of birthing.

n Peak is identified by slight slowing in rate of dilatation when 9 cm is reached (deceleration on graph).

n At 10 cm irresistible urge to push.

Second Stage of Labor

n Full dilatation and cervical effacement to birth of infant.

n Contractions change from crescendo-decrescendo pattern to uncontrollable urge to push.

n N/V, she perspires, blood vessels in neck become distended.

n Perineum begins to bulge and appear tense.

n Anus appears everted, stool expelled, vaginal introitus opens, fetal head visible.

n Crowning – at first slitlike opening then oval, then circular, from size of dime to that of a quarter, then half-dollar.

n She can not stop pushing, all energy is directed toward birth.

n Third Stage:

n Placental stage begins with the birth of the infant and ends with delivery of the placenta

n Two separate phases:

n Placental separation

n Placental expulsion

Third Stage of Labor

n After birth the uterus can be palpated as a firm, round mass, inferior to level of umbilicus.

n Uterine contractions begin again and organ assumes a discoid shape until separated, approx. 5 min.

n Placental Separation:

n Occurs automatically as uterus resumes contractions.

n Folding and separation of the placenta occurs.

n Active bleeding on maternal surface of placenta and this helps separate the placenta by pushing it away from its attachment site.

n Signs:

n Lengthening of the umbilical cord

n Sudden gush of vaginal blood

n Change in the shape of the uterus

n Schultze-shiny and glistening side of placenta fetal surface. (80%)

n Duncan-looks raw, red irregular with ridges, maternal surface.

Third Stage of Labor

n Normal blood loss-300 to 500 ml.

n Placental Expulsion:

n After separation, the placenta is delivered by natural bearing down effort or gentle pressure on fundus by physician.

n Never apply pressure to uterus in uncontracted state or uterus may evert and hemorrhage.

n Placenta can be removed manually.

n Saved for stem cell research.

Responses to Labor

n Maternal Response:

n Almost all body systems are affected.

n Cardiovascular

n Cardiac output

n Blood pressure

n Hemopoietic system

n Respiratory

n Temperature regulation

n Fluid balance

n Urinary

n Musculoskeletal

n Gastrointestinal

n Neurologic and sensory

n Psychological Responses:

n Fatigue

n Fear

n Cultural influences

n Fetal responses:

n Neurologic system

n Cardiovascular

n Integumentary

n Musculoskeletal

n Respiratory