Ch. 15 Labor and Birth Processes Flashcards
What are the five factors that affect the process of labor and birth (5 P’s)?
Passenger (fetus & placenta), Passageway (birth control), Powers (contractions), Position of mother, & Psychologic response
What are several interacting factors that effect the movement of the passenger during birth?
The size of the fetal head, fetal presentation, fetal lie, fetal attitude, and fetal position
What bones is the fetal skull composed of?
2 parietal bones, 2 temporal bones, the frontal bone, and the occipital bone
What membranous sutures are the bones of the fetal skull united by?
The sagittal, lambdoidal, coronal, and frontal
What are the membrane-filled spaces located where the sutures intersect called?
The fontanels
What does the palpation of fontanels and sutures during vaginal examination reveal?
Fetal presentation, position, and attitude
What makes the skull flexible to accommodate the infant birth?
Sutures and fontanels
What is slight overlapping of the bones of the fetal skull that occurs during childbirth called and what does it permit?
Molding. It permits the skull to adapt to the various pelvic diameters
What is the part of the fetus that enters the pelvic inlet first called?
Presentation
What are the 3 main types of presentation?
Cephalic (head first), Breech (buttocks first), and shoulder
What is the part of the fetal body first felt by the examining finger during a vaginal exam called?
Presenting part
Name the 3 main fetal presenting parts.
Occiput, sacrum, and scapula
What is the presenting part in a cephalic presentation?
The occiput
What is the presenting part in a breech presentation?
The sacrum
What is the presenting part in a shoulder presentation?
The scapula
What is the relationship of the long axis (spine) of the fetus to the long axis (spine) of the mother called?
The lie
What are the 2 primary lies?
Longitudinal (or vertical) and transverse (horizontal or oblique)
What is a longitudinal (or vertical) lie?
The long axis of the fetus is parallel with the long axis of the mother
What is a transverse (horizontal or oblique) lie?
The long axis of the fetus is at a right angle diagonal to the long axis of the mother
What type of lie is seen in either cephalic or breech presentations?
Longitudinal lies
Can a vaginal birth occur when the fetus stays in a transverse lie?
No
What is the relationship of the fetal body parts to one another called?
The attitude (posture)
What is the most common type of attitude?
General flexion
Describe general flexion attitude.
The fetus’s chin is flexed on the chest, the thighs are flexed on the abdomen, and the legs are flexed at the knees. The arms are crossed over the thorax, and the umbilical cord lies between the arms and the legs
What is a suboccipitobregmatic diameter?
Complete flexion of head on chest so that smallest diameter enters the pelvis
What is an occiptofrontal diameter?
Moderate extension (military attitude) so that large diameter enters
What is an occipitomental diameter?
Marked extension (deflection) so that the largest diameter, which is too large to permit head to enter pelvis, is presenting
What is the largest transverse diameter of the fetal skull and what is the diameter at term?
Biparietal diameter; 9.25 cm at term
What is the smallest anteroposterior diameter of the fetal skull to enter the maternal pelvis when the fetal head is in completed flexion and what is the diameter at term?
Suboccipitobregmatic diameter; 9.5 cm at term
What is the relationship of the fetal presenting part to the four quadrants of the maternal pelvis called?
The position
What does the first letter of the position abbreviation stand for?
The location of the presenting part in the right (R) or left (L) side of the mother’s pelvis
What does the middle letter of the position abbreviation stand for?
The specific presenting part of the fetus (O for occiput, S for sacrum, M for mentum [chin], & Sc for scapula [shoulder])
What does the third letter of the position abbreviation stand for?
The location of the presenting part in relation to the anterior (A), posterior (P), or transverse (T) portion of the maternal pelvis
What does ROA mean?
The occiput is the presenting part and is located in the right anterior quadrant of the maternal pelvis
What does LSP mean?
The sacrum is the presenting part and is located in the left posterior quadrant of the maternal pelvis
Term that indicates that the largest transverse diameter of the presenting part has passed through the maternal pelvic brim or inlet into the true pelvis reaching the level of the ischial spines.
Engagement (usually corresponds to station 0)
What is the relationship of the presenting part of the fetus to an imaginary line drawn between the maternal ischial spines called and what does it measure?
The station. This is a measure of the degree of fetal descent through the birth canal
What is the station when the lowermost portion of the presenting part is 1 cm above the spines?
Minus (-) 1
What is the station when its at the level of the spines?
0 (zero)
What is the station when the presenting part is 1 cm below the spines?
Plus (+) 1
When is birth imminent according to the station?
When the presenting part is at +4 to +5 cm
What are the 2 components of the maternal passageway or birth canal?
Bony pelvis and soft tissue
What is the false pelvis and does it play a role in childbearing?
The false pelvis is the part above the brim and plays no part in childbearing
What are the 3 planes in the true pelvis?
The inlet, or brim; The midpelvis, or cavity; & the outlet
What is the passageway, or birth canal, composed of?
Bony pelvis, lower uterine segment, cervix, pelvic floor muscles, vagina, introitus (external opening to the vagina)
What is the purpose of contractions?
Exerts downward pressure on the fetus, pushing it against the cervix
What is the primary powers and what does it signal?
Involuntary uterine contractions that signal the beginning of labor
What is secondary powers and when does this occur?
Once the cervix has dilated, voluntary bearing-down efforts by the woman augment the force of the involuntary contractions
What does frequency of involuntary contractions mean?
The time from the beginning of one contraction to the beginning of the next
What does the duration of involuntary contractions refer to?
Length of contraction
What does the intensity of involuntary contractions refer to?
The strength of contraction
What is the shortening and thinning of the cervix during the first stage of labor called and how is it expressed?
Effacement. Expressed as a percentage
What is the enlargement of widening of the cervical opening (os) and the cervical canal, which occurs once labor has begun called and how is it expressed?
Dilation and the degree of progress is expressed in centimeters (cm) from less than 1 cm to 10 cm
When can the cervix no longer be palpated?
When the cervix is fully dilated (and completely retracted)
What marks the end of the first stage of labor?
Full cervical dilation (10cm)
Why are secondary powers used?
Secondary powers (bearing-down efforts) aid in expulsion of the fetus as she contracts her diaphragm and abdominal muscles and pushes
What is the result of bearing-down efforts (secondary powers)?
Results in increased intraabdominal pressure that compresses the uterus on all sides and adds to the power of the expulsive forces
What fetal complications are associated with prolonged breath holding and forceful pushing efforts?
Fetal hypoxia and subsequent acidosis
What is the Ferguson reflex?
Stretch receptors in the posterior vagina cause release of endogenous oxytocin that triggers the maternal urge to bear down
What problems are associated with direct pushing?
Perineal floor problems
What do frequent changes in position during labor do?
Relieves fatigue, increases comfort, and improves circulation
What promotes the decent of the fetus?
Gravity
How is an upright position during labor beneficial?
Increases cardiac output which improves blood flow to the uteroplacental unit and the maternal kidneys
What is compromised if the patient is placed in the supine position during labor?
Cardiac output is compromised due to the compression of the descending aorta and ascending vena cava
What does decreased cardiac output result in during labor if in the supine position?
Supine hypotension that decreases placental perfusion
If the patient wishes to lie down during labor, what position should be suggested?
Lateral position
What position may be used to relieve backache if the fetus is in an occipitoposterior position and what else may this position assist in?
The “all fours” position (hands and knees). May also assist in anterior rotation of the fetus and in cases of shoulder dystocia
What is the descent of the fetus’s presenting part into the true pelvis approximately 2 weeks before term for the primigravida and after uterine contractions are established and true labor is in progress for the multipara called?
Lightening or “dropping”
What is the definition of labor?
Process of moving fetus, placenta, and membranes out of the uterus and through the birth canal
List some signs that may precede labor.
Lightening, return of urinary frequency, backache, stronger Braxton Hicks contractions, weight loss of 0.5-1.5kg, surge of energy, cervical ripening, increased vaginal discharge (bloody show), and possible rupture of membranes
What factors are involved in the onset of true labor?
Changing in maternal uterus, cervix, and pituitary gland
Define primary powers of labor.
Involuntary uterine contractions
Define secondary powers of labor.
Bearing-down (pushing)
What is the brownish or blood-tinged cervical mucus called and what does it represent?
Operculum which represents the passage of the mucous plug as the cervix ripens in preparation for labor
What does the course of normal labor consist of?
(1)Regular progression of uterine contractions, (2)Effacement and progressive dilation of the cervix, & (3) Progress in descent of the presenting part
Define the first stage of labor
Lasts from the onset of regular uterine contractions to full dilation (10cm) of the cervix
What are the 3 phases of the first stage of labor?
Latent phase (more progress in effacement of the cervix and little increase in descent); Active and transition phases (more rapid dilation of the cervix and increased rate of descent of the presenting part)
Define the second stage of labor.
Lasts from the time the cervix is fully dilated (10cm) to the birth of the fetus
Describe the first phase of the second stage of labor.
A period that begins about the time of complete dilation of the uterus, when the contractions are weak or not noticeable and the woman is not feeling the urge to push, is resting, or is exerting only small bearing-down efforts with contractions
Describe the second phase of the second stage of labor.
A period when contractions resume, the woman is making strong bearing-down efforts, and the fetal station is advancing
Describe the third phase of the second stage of labor.
A period lasting from the crowning until the birth
Define the third stage of labor.
Lasts from the birth of the fetus until the placenta is delivered
When does the placenta normally separate and when is it delivered?
The placenta normally separates with the 3rd or 4th strong uterine contraction after the infant has been born. After it has separated, the placenta can be delivered with the next uterine contraction
Define the forth stage of labor.
Arbitrarily lasts about 2 hrs after delivery of the placenta. It is the period of immediate recovery, when homeostasis is reestablished
What is used to predict the likelihood of preterm labor in women who are at increased risk and what is it?
Fetal fibronectin = protein found in plasma and cervicovaginal secretions of pregnant women before the onset of labor
What is the pushing method during the second stage of labor characterized by a closed glottis with prolonged bearing down called?
Valsalva maneuver
What is the mechanism of labor?
The seven turns and adjustments of the fetal head to facilitate passage through the birth canal
What are the seven cardinal movements in vertex presentation (head down)?
Engagement, descent, flexion, internal rotation, extension, external rotation (restitution), and finally birth by expulsion
What position is it when the head engages in the pelvis parallel to the anteroposterior plane of the pelvis?
Synclitic position
What position is it when the head is deflected anteriorly or posteriorly in the pelvis?
Asynclitism, which can facilitate descent because the head is being positioned to accommodate to the pelvic cavity
What can extreme asynclitism cause?
Cephalopelvic disproportion, even in a normal-size pelvis, because the head is positioned so that it cannot descend
What does descent refer to during labor?
The progress of the presenting part through the pelvis
What are the 4 forces in which the descent depends upon?
(1) Pressure exerted by the amniotic fluid, (2) Direct pressure exerted by the contracting fundus on the fetus, (3) Force of the contraction of the maternal diaphragm and abdominal muscles in the second stage of labor, and (4) extension and straightening of the fetal body
How is the degree of descent measured during labor?
By the station of the presenting part
When does the flexion movement occur during labor?
As soon as the descending head meets resistance from the cervix, pelvic wall, or pelvic floor, it normally flexes so that the chin is brought into closer contact with the fetal chest
When does internal rotation begin during labor and describe this internal rotation?
Begins at the level of the ischial spines but is not completed until the presenting part reaches the lower pelvis. As the occiput rotates anteriorly, the face rotates posteriorly
What plays an important role in achieving anterior rotation?
Bother the levator ani muscles and the bony pelvis
How does the fetal head emerge by extension?
After the occiput passes under the lower border of the symphysis pubis the occiput appears first, then the face, and finally the chin
What movement is referred to as restitution during labor?
After the head is born, it rotates briefly to the position it occupied when it was engaged in the inlet. The 45-degree turn realigns the infant’s head with her or his back and shoulders
When does external rotation occur during labor?
The shoulders engage and descend in maneuvers similar to those of the head; the anterior shoulder descends first by rotating to the midline and is delivered under the pubic arch; the posterior shoulder is guided over the perineum
Describe expulsion during labor.
After birth of the shoulders, the head and shoulders are lifted up toward the mother’s pubic bone, and the trunk of the body is born by flexing it laterally in the direction of the symphysis pubis
What are some fetal physiologic adaptations made during labor?
Fetal heart rate (FHR), fetal circulation, respiratory movements, and other behaviors
What does FHR monitoring provide during labor?
Provides reliable and predicitive information about the condition of the fetus related to oxygenation
What is the average FHR at term?
140 bpm
What is the normal FHR range?
110-160 bpm
What are temporary accelerations and slight early decelerations of the FHR expected in response to?
Spontaneous fetal movement, vaginal examination, fundal pressure, uterine contractions, abdominal palpation, and fetal head compression
What are some factors that affect fetal circulation?
Maternal position, uterine contractions, BP, and umbilical cord blood flow
What changes stimulate chemoreceptors in the aorta and carotid bodies to prepare the fetus for initiating respirations?
Fetal lung fluid is cleared from the air passages as the infant passes through the birth canal during labor and (vaginal) birth; Fetal oxygen pressure (PO2) decreases; Arterial carbon dioxide pressure (PCO2) increases; Arterial pH decreases; Bicarbonate level decreases; Fetal respiratory movements decrease during labor
What respiratory adaptations does the mother exhibit during labor?
Respiratory rate increases
What cardiovascular adaptations does the mother exhibit during labor?
Cardiac output increases 10-15% in first stage and 30-50% in second stage; HR increases slightly in first and second stages; Systolic BP increases during uterine contractions in first stage; Systolic and diastolic pressures increase during uterine contractions in second stage; WBC count increases
What renal adaptations does the mother exhibit during labor?
Proteinuria (+1) may occur
What GI adaptations does the mother exhibit during labor?
Gastric motility and absorption of solid food is decreased; N/V may occur during transition to second stage labor
What endocrine adaptations does the mother exhibit during labor?
Blood glucose level decreases
What is the morphine-like chemicals produced naturally in the body, which raise the pain threshold and produce sedation called?
Endogenus endorphins
