Process of Normal Labor

Process of Normal Labor
Chapter 6 Process of Normal Labor Review chapter objectives. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Process of Labor and Birth
Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.
Objectives Define key terms listed. Explain labor, lightening, vaginal show, effacement, and cervical dilation. Recognize spontaneous rupture of membranes. Interpret the events that signal approaching labor. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

The Process of Labor Labor is the process by which fetus, placenta, and amniotic membranes are expelled from the uterus Fairly predictable sequence of events Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Factors Contributing to Onset of Labor
Hormones Stretching of uterus Interaction among Placenta Fetal pituitary gland Hypothalamus Adrenal glands Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Other Factors Preparation Prenatal classes help reduce fear of unknown Position Maternal preferences (sitting, squatting, etc) my influence progression of labor Professional help Nurse to help coach through labor process Procedures Can interrupt concentration/rapport during labor People Presence of supportive family can influence smooth progression of labor Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Major Variables in the Birth Process

“Four Ps” Pelvis—size and shape Passenger—fetus size and position Powers—effectiveness of contractions Psyche—preparation, previous birth experiences Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Fetal Head Can withstand pressure of uterine contractions and descent through birth canal Stronger pressure is applied to head after rupture of membranes Amniotic fluid no longer providing a “cushion” Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Bony Skull of Fetal Head
Composed of several bones Separated by strong connective tissue Sutures Fontanelles Anterior and posterior See Figure 6-1 (p. 93). Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Audience Response System Question 1
Fetal heart rate is lowered during a contraction due to: Fetal position Maternal stress Decreased umbilical blood flow Decreased uterine blood flow Answer: D. During the contraction, there is decreased blood flow through the uterine arteries and intervillous spaces. This decline leads to a lowered fetal heart rate. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Powers, Positions and Psyche

Objectives List the four main variables in the birth process. Describe the ability of the uterine muscles to contract and relax. Differentiate three distinctive characteristics of labor contractions. Differentiate between false and true labor. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Objectives (cont.) Illustrate how frequency, duration, and intensity of contractions are monitored. Describe fetal attitude, fetal lie, and fetal presentation. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Fetopelvic Relationship
Fetal attitude Relation of fetal parts to one another; flexion Fetal lie Relation of longitudinal axis of fetus to mother (should be parallel) Fetal presentation Body part lowest in mother’s pelvis (cephalic preferred) Fetal position R (right), L (left), O (occiput), S (sacrum), M (mentum [face]) A (anterior), P (posterior) Fetal attitude: relation of fetal parts to one another (see Figure 6-2 [p. 93]). Fetal lie: relation of longitudinal axis of fetus to longitudinal axis of mother. Fetal presentation: determined by body part of fetus that is lowest in mother’s pelvis (see Figure 6-3 [p. 94]). Fetal position: relation of some designated point on the presenting part to the quadrants of the maternal pelvis. Review Box 6-1 (p. 95). Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Station How far fetal presenting part has descended into mother’s pelvis Imaginary line between ischial spines of maternal pelvis Crowning: fetal head can be seen at vaginal opening Movement of the presenting part downward toward the outlet of the pelvis occurs in the 9th month and is known as _____. Answer: lightening Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Powers: Uterine Contractions
Begin in top of uterus (fundus) Spread throughout uterus in about 15 seconds Retraction (or brachystasis): uterine muscles able to maintain shortening achieved during contractions Results in progressive decrease in size of uterine cavity Thickening of muscle tissue in upper portion of uterus Forces fetus to descend Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Uterine (Labor) Contractions
Each contraction should be followed by period of relaxation Contractions cause decreased blood flow through Uterine arteries Intervillous spaces Causes decline in fetal heart rate If contractions become more frequent and prolonged, the decrease in blood flow can be cumulative and compromise the fetus; also known as fetal distress. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Contractions and Maternal Position
Supine: contractions likely to be more frequent but not as strong Side-lying: contractions likely less frequent but of greater intensity Improves Progress of labor Oxygenation of the fetus Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Contractions and the Cervix
Cause cervix to efface (thin) and dilate (open) Before labor, cervix is 2-cm tubular structure Contractions push fetus downward and pull cervix upward Cervix becomes thinner and shorter Effacement determined by vaginal exam Described in percentage of original cervical length When 100% effaced, cervix feels like a thin, slick membrane over the fetus. See Figure 6-5 (p. 97). Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Cervical Dilation Determined by vaginal examination Described in centimeters Full dilation is 10 cm What is estimated by touch rather than being precisely measured? Answer: dilation and effacement Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Second Stage of Labor Begins when cervix is 100% dilated Woman uses abdominal muscles to increase intra-abdominal pressure, thereby increasing the force of the contraction Bearing-down effort with abdominal muscles is consciously controlled Helps to expel fetus Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Uterine Contractions Produce cervical effacement and dilation Cause fetus to engage and rotate Cause fetus to be delivered Detach and expel the placenta See Safety Alert—When to Report Contractions (p. 98). Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Characteristics of Uterine Contractions
Frequency Beginning of one contraction to beginning of next Duration Beginning of contraction to end of same contraction Intensity Strength: mild, moderate, strong Interval Amount of time uterus relaxes between contractions Mild contraction: fundus easily indented with fingertips; feels similar to tip of nose. Moderate contraction: can be indented with fingertips but with more difficulty; fundus feels similar to chin. Strong or firm: cannot be readily indented with fingertips; feels similar to forehead. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Phases of Contractions
Increment The period of increasing strength Peak, or acme The period of greatest strength Decrement The period of decreasing strength See Figure 6-6 (p. 97). Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Psyche Part of labor process Anxiety or fear decreases woman’s ability to cope Maternal catecholamines (stress hormones) known to inhibit contractility and placental blood flow Relaxation augments natural process of labor Childbirth classes may help by teaching various relaxation techniques that the woman can employ during the labor and delivery process. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Conservation of Energy
Should be stressed until it is needed in the expulsion state Will help woman avoid exhaustion and the development of an electrolyte imbalance Can occur with hyperventilation and profuse perspiration How does an electrolyte imbalance occur? Answer: it can occur with hyperventilation and profuse perspiration. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Events Before the Onset of Labor
Lightening Vaginal discharge (show) Energy spurt False labor No cervical changes Spontaneous rupture of membranes Cervical changes Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Lightening Fetus begins to settle in maternal pelvis Moves downward toward pelvic outlet Physical changes in woman Easier breathing More frequent urination Leg cramps Edema of the lower extremities Once fetus has dropped, there is more pressure from the fetal head on the maternal blood vessels, nerves, and bladder. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Vaginal Discharge (Show)
Blood-tinged mucous plug dislodges from cervical os From rupture of superficial blood vessel Pink-stained mucus Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Energy Spurt Some women have this a day or two before delivery Referred to as “nesting” Inform woman not to overexert herself Will need energy for labor and delivery process Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

False Labor Braxton-Hicks contractions Painless Can be felt when hand is placed on abdomen Uncoordinated and irregular May notice an increase in the last 2 to 3 weeks of gestation Cervix typically has not dilated, and contractions either remain irregular or stop entirely. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Difference Between True and False Labor
Cervical changes, such as dilation, occur with true labor Contractions become regular and increase in intensity Refer to Table 6-1 (p. 99). Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Rupture of Membranes Spontaneous rupture of membranes (SROM) Can be a trickle or rush of fluid “My water broke” At term, woman usually starts labor within 24 hours of SROM If labor does not start after 24 hours, induction of labor may occur Nitrazine paper test To determine if fluid is amniotic or urine Induction is the artificial beginning of labor, usually by giving the woman IV medications. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Cervical Changes Effacement: shortening and thinning of the cervix Normally is 1 to 2 cm in length When 100% effaced, cervix almost disappears Dilation: enlargement of cervical os (opening) from 0 to 10 cm At 4 cm woman’s active labor usually progresses to completion Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Contractions are described by frequency, duration, intensity, and: Interval Relaxation Increment Presentation Answer: A. It is important to know how much time has elapsed between each contraction. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Objectives List the six positions that the occiput of the fetal head may occupy in relation to the maternal pelvis. Describe the term station as it relates to the maternal pelvis. Distinguish six factors that influence the course of labor. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Objectives (cont.) Interpret what is accomplished in each of the four stages of labor. Summarize the response of each body system to the labor process. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Mechanisms of Labor Cardinal movements are a series of actions that reflect changes in the posture of the fetus as it adapts to the birth canal Most take place during second stage Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Cardinal Movements of Labor
Mechanisms of labor (fetal posture changes) dictated by Pelvic diameters Maternal soft tissues Size of fetus Strength of contractions Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Adaptive Movements Of fetal head and shoulders Includes Descent and engagement Flexion Internal rotation Extension External rotation Expulsion Placental expulsion Descent cannot be isolated from the other adaptive movements because_____. Answer: it occurs throughout the labor process. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Engagement Occurs when biparietal diameter of fetal head reaches level of ischial spine of mother’s pelvis Presenting part is at 0 station or lower Descent may occur before or after labor begins and is caused by the pressure of _____. Answer: the pressure of contractions and the amniotic fluid. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Extension Begins as fetal head reaches pelvic floor Pivots under symphysis pubis Advances upward As extension progresses, occiput appears at vaginal opening (crowning) Completed on delivery of fetal head Extension results from a combination of pressure from the uterine contractions, abdominal pressure exerted by the mother’s pushing, and resistance from the pelvic floor. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

External Rotation Called restitution Occurs after head delivered Head immediately rotates to transverse position Shoulders align themselves to antero-posterior diameter of pelvic outlet Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Expulsion Anterior shoulder rotates forward, delivers, followed by posterior shoulder Rest of body is then delivered Birth of fetus ends second stage of labor Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Placental Expulsion Not a mechanism of labor Usually takes anywhere from 5 to 30 minutes after delivery of fetus Signs of placental separation Lengthening of cord Change in shape of uterus Trickle or gush of blood from vagina Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Placental Delivery Duncan mechanism: placenta implanted low in uterus (dull, maternal side first) Schultze mechanism: placenta implanted near fundus (fetal, shiny side first) Delivery of placenta ends third stage of labor Refer to Figure 7-15 (p. 138). Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

The Four Stages of Labor

First Stage Longest and most variable Begins with onset of regular contractions Contractions complete Effacement of cervical canal (100%) Dilation of cervix (10 cm) This stage is complete when cervix is fully effaced and dilated Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Latent Phase Contractions become stabilized Usually mild Occur every 10 to 15 minutes Last about 15 to 20 seconds Fetal descent begins in earnest Woman able to focus on any teaching being provided by health care team Able to cope with what she is experiencing Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Active Phase Contractions stronger and longer Contractions increase to 30 to 45 seconds in length and occur about every 5 minutes Intensity is moderate to strong Result is cervical dilation progressing from 4 to 7 cm Fetus descends more Assist woman with breathing techniques Woman questions her ability to cope with what she is experiencing Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Transition Phase Dilation continues but is slower Contractions more frequent, last longer (60 to 90 seconds), and are stronger Woman may exhibit certain behaviors during this phase Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Characteristics of Transition Phase
Restlessness Difficulty following directions Hyperventilation Perspiration Belching or hiccupping Nausea or vomiting Increased rectal pressure (“I need to have a bowel movement.”) May be very irritable Refer to Box 6-2 (p. 101) for the complete list of characteristics. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Completion of Transition Phase
Woman may feel a splitting sensation by force of contractions and pressure of fetal head near cervix As head descends, she may have urge to push because of pressure on sacral nerves from the head Perineum begins to bulge and flatten Head seen at vaginal opening Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Second Stage of Labor Begins when cervix is completely dilated Ends with birth of fetus Woman may feel urge to bear down Uses abdominal muscles to assist with involuntary uterine contractions Coach her not to hold breath more than 5 seconds at a time while pushing; may trigger a Valsalva’s maneuver Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Valsalva’s Maneuver Results from closed glottis, which leads to increased intrathoracic and cardiovascular pressure Can diminish perfusion across placenta Results in fetal hypoxia, and abnormalities can be seen in the fetal heart rate Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Characteristics of Second Stage of Labor
Can last from a few minutes to 2 hours Fetal head causes bulging of perineum Crowning occurs when head is seen at external opening of vagina Head appears to recede between contractions Contractions forceful Occur every 2 to 3 minutes and last 60 to 90 seconds Increased bloody show usually occurs Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Delivery of Fetus Nose and mouth are suctioned once head is delivered Once body is delivered, umbilical cord is clamped in two places and cut Nose and mouth may again be suctioned Baby is handed off to pediatric nurse and pediatrician for examination Mother is tended by obstetrician or nurse- midwife Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Third Stage of Labor Referred to as the placental separation stage Begins with birth of fetus Ends with expulsion of placenta Can last up to 30 minutes Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Fourth Stage of Labor Stage of recovery Begins with delivery of placenta Lasts through 1 to 4 hours or until mother’s vital signs are stable Blood loss during labor and delivery process can range from 250 to 500 mL Leads to Drop in blood pressure Increase in pulse rate Why would blood loss cause the changes in blood pressure and pulse rate? Answer: the heart has to work harder to pump less blood throughout the body to provide oxygen and nutrients and remove waste products. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Uterus in Fourth Stage of Labor
Must stay contracted to compress open blood vessels at placental site Palpable as a firm, rounded mass at or below level of umbilicus First hour after delivery is critical in observing mother for signs of excessive bleeding and assessing firmness of contracting uterus Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

Physiologic Changes in Labor
All of the woman’s body systems are affected by the labor process Physiologic changes can be seen either directly or indirectly based on the clinical symptoms she exhibits Nursing interventions are important and need to be provided in a timely manner Review Table 6-2 (pp ). Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

What stage of labor is completed when the cervix is fully effaced and dilated? First Second Third Fourth Answer: A, contractions are completed in that the cervix is 100% effaced and dilated. Copyright © 2012, 2008 by Saunders, an imprint of Elsevier Inc.

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