Flashcards in NURS 405: Chapter 12? (Needs to be transferred) Deck (62):
Normal Labor: Theories of onset
-The exact mechanisms that initiate labor remain unknown.
-Natural labor begins when forces favoring continuation of pregnancy are offset by forces favoring its end.
Factors that appear to have a role in starting labor include:
-Changes in ratio of maternal estrogen and progesterone -> so that estrogen levels are higher than progesterone levels. (Estrogen causes stimulation of uterine muscle contraction)
-Prostaglandin production increases
-Natural oxytocin maintains labor
-Stretching, pressure and irritation of the uterus and cervix increase as the fetus reaches term size.
How does increased prostaglandin production play a role in starting labor?
-Prostaglandins play a role in preparing the uterus for oxytocin stimulation at term.
-Prostaglandins are secreted from the lower area of the fetal membrane during labor and may reflect inflammation caused by intact with microorganisms from the vagina.
How does the fetus play a role in uterine stimulation during labor?
-The fetal membranes release prostaglandins in high concentrations during labor.
-In addition to fetal oxytocin secretion, large quantities of cortisol are secreted by fetal adrenal, possibly acting as a uterine stimulant.
Increased secretion of natural oxytocin,
Appears to maintain labor once it has begun; oxytocin alone does not appear to start labor but may play a part in labor’s initiator in conjunction with other substances.
How does cervical stretching play a role in starting labor?
-As the fetal head stretches the cervix, it causes the fundus of the uterus to contract, pushing the fetal head against the cervix and causing more fundal contractions.
-Cervical stretching also causes secretion of oxytocin.
Premonitory Signs of Labor include
-Braxton Hick’s Contractions
Braxton Hick’s Contractions
• Fetus descends into pelvic inlet.
• The woman notices that she breathes more easily because upward pressure on her diaphragm is reduced
Lightening can cause
• Increased pressure on her bladder causes her to urinate more frequently
• Pressure of the fetal head in the pelvis also may cause leg cramps and edema
Lightening is most noticeable in
Lightening occurs when?
About 2-3 weeks before the natural onset of labor**
Causes blood-tinged discharge.
Mucousy type of blood.
When does bloody show begin?
May begin several days to a few weeks before the onset of labor.
May also not begin until labor starts.
A recent vaginal examination or sexual intercourse may also result in
Small amounts of bloody show because it disrupts these small vessels.
Bloody show during labor
Increases as the cervix completes dilation and effacement
Women who have previously had vaginal birth often have
Less bloody show than multiparas.
Cervix begins to soften and weaken (ripening)
-Some women have a sudden increase in energy, which is called “nesting”.
-Women should be cautioned to conserve their energy so that they are not exhausted when labor actually begins.
Weight loss of 1-3 lbs may occur because
Altered estrogen and progesterone ratio causes excretion of some of the extra fluid that accumulates during pregnancy.
True Labor is characterized by
• Progressive change in the cervix
• Rapid increase in effacement & dilation
• Contractions at regular intervals - increase in duration and intensity
• Discomfort begins in back and radiates to front of abdomen
• Walking intensifies contractions
• Resting or relaxing in warm water does not decrease intensity
False Labor aka Prodromal Labor or Prelabor is characterized by:
• Irregular contractions that do not increase in duration or intensity
• Contractions are lessened by walking, rest, or warm water
• Discomfort felt primarily in abdomen
• Contractions produce no effect on cervix
Cardinal movements of labor occur as the fetus is moved through the pelvis during birth.
What are the labor mechanisms?
1. Fetal position changes and descent through pelvis
Measurement of descent of the fetal presenting part in relation to the level of the ischial spines.
Ischial spines: 0 station
In vertex presentation, the mechanisms include
-Descent of the fetal presenting part through the true pelvis
-Engagement of the fetal presenting part as its widest diameter reaches the level of the ischial spines of the mother’s pelvis
-Flexion of the fetal head, allowing the smallest head diameters to all gin with the smaller diameters of the midpelvis as the fetus descends
-Internal rotation to allow the largest fetal head diameters to align with the largest maternal pelvic diameter
-Extension of the fetal head as the neck pivots on the inner margin of the symphysis pubis, allowing the head to align with the curves of the pelvic outlet
-External rotation of the fetal head, aligning the head with the shoulders during expulsion
-Expulsion of the fetal shoulders and fetal body
What is the purpose for mechanism of labor?
To effectively use the available space in the maternal pelvis
The first stage of labor has three phases:
Stages of Labor: First Stage Characteristics
-Is the longest for both nulliparous and parous women.
When the active phase begins, the cervix of the nullipara usually dilates about how much per hour?
1.2 cm per hour
When the active phase begins, the cervix of the multipara usually dilates about how much per hour?
1.5 cm per hour
First Stage of Labor: Latent Phase
Is the first 0-3 cm of cervical dilation.
What medications are usually given during the latent phase?
Demerol or dilaudid, statol
(Must take VS before giving medications)
What are physiologic changes that occur during the latent phase of labor?
• Regular, mild contractions begin and increase in intensity and frequency.
• Contracting uterus can be easily indented with the fingertips and progresses to moderate contractions, during which the uterine muscle is indented with more difficulty
• Cervical effacement and dilation begins
What are psychological changes that occur during the latent phase of labor?
• She is anxious as she realizes that these contractions are not Braxton Hicks contractions but the “real thing”
• Relief that labor has begun
• High excitement with some anxiety
First Stage of Labor: Active Phase
-4-7cm of cervical dilation**
-Women who choose to take pain medication and regional analgesia usually do so during this phase
What are the physiologic changes that can occur during the active phase of labor?
1. Contractions increase in intensity, frequency and duration. Reach their peak and intensity quickly and stay at the peak longer than during the latent phase.
2. Fetus begins to descend into the pelvis
3. More rapid progress
What is the normal frequency of contractions during the active phase?
2-5 minutes apart
What is the normal duration of contractions during the active phase of labor?
What is the normal intensity of contractions during the active phase of labor?
Ranges from moderate to strong
What are psychological changes that occur during the active phase of labor?
• Fear of loss of control
• Anxiety increases -> may feel helpless as the contractions intensify
• Her behaviors are typical of a person concentrating intently on a demanding task
First Stage of Labor: Transition Phase
8-10 cm of cervical dilation
What are physiologic changes that occur during the transition phase of labor?
1. Contractions can continue to increase in intensity, duration and frequency.
2. Fetus descends rapidly into the birth passage.
3. Bloody show often increases with the completion of cervical dilation.
4. Strong contractions combined with fetal descent may cause the woman to have an urge to push and bear down during contractions.
5. May experience rectal pressure; N/V
What is the normal intensity of contractions during the transitional phase of labor?
What is the normal frequency of contractions during the transitional phase of labor?
1.5-2 minutes apart
What is the normal duration of contractions during the transitional phase of labor?
What are psychological changes that occur during the transitional phase of labor?
• The woman who does not choose epidural analgesia often finds the transition phase to be the most difficult part of her labor
• Increased feelings of anxiety
• Eager to complete birth experience
• Need to have support person or nurse at bedside
Second Stage of Labor
Begins with complete dilation (10 cm) and full effacement (100%) of the cervix and ends with the birth of the baby.
What are the normal characteristics of contractions during the second stage of labor?
Frequency: 2-3 minutes apart
Duration: 40-60 seconds
What happens during the second stage of labor?
• May say that she needs to have a bowel movement or say “the baby's coming” or “I have to push”
• Woman exerts intense physical effort to push her baby out
• She feels tremendous relief and excitement as the second stage ends with the birth of the baby
Third Stage of Labor
Begins with the birth of the baby and ends with the expulsion of the placenta.
How long does the third stage of labor take?
This is the shortest stage with an average length of 5-30 minutes.
What are physiologic changes that occur during the third stage of labor?
• Placental separation: Uterus contracts and placenta begins to separate
• Placental delivery: Woman bears down and delivers placenta (physician may put slight traction on cord to assist delivery of placenta)
• When the infant is born, the uterine cavity becomes much smaller; the reduced size decreases the size of the placenta site, causing it to separate from the uterine wall
What are four signs that suggest placental separation?
1. The uterus has a spherical shape.
2. The uterus rises upward in the abdomen as the placenta descends into the vagina and pushes the fundus upward.
3. The cord descends further from the vagina.
4. A gush of blood appears as blood trapped behind the placenta is released.
What are psychological changes that can occur during the third stage?
• May feel relief at completion of birth
• Usually focused on welfare of infant and may not recognize that placental expulsion is occurring
Fourth Stage of Labor
The stage of physical recovery for the mother and infant.
Lasts from the delivery of the placenta through the first 1-4 hours after birth.
What are the physiologic changes that occur during the fourth stage of labor
• One of the first thing to look for in this stage is a full bladder. Urine may be retained due to decreased bladder tone and possible trauma to the bladder.
• Immediately after birth, the firmly contracted uterus can be palpated through the abdominal wall as a firm, rounded mass.
• Increased pulse and decreased blood pressure due to redistribution of blood from uterus and blood loss
• Uterus remains contracted and located between umbilicus and symphysis pubis
• May experience a shaking chill that lasts for about 20 minutes and subsides spontaneously.
What are some things you can do during the fourth stage of labor for the mother?
• Allow pt. to eat and drink a little bit cause they are hungry and exhausted
• A warm blanket, a hot drink, or soup may help shorten the chill that can occur during this stage.
What are some psychological changes that can occur during the fourth stage of labor?
• May experience euphoria and energized at birth of child
How often are vital signs assessed in the fourth stage of labor?
Fundal tone and lochia