Chapter 12: Process Of Birth Flashcards
What are the three phases of the contraction cycle?
- Increment
- Peak
- Decrement
Contraction Cycle: Increment
Occurs as the contraction begins in the fundus and spreads throughout the uterus.
Starts to incline and works its way up with strength.
Contraction Cycle: Peak
Or acme, is the period during which the contraction is most intense.
Patient feels the most intense pain.
Contraction Cycle: Decrement
The period of decreasing intensity as the uterine relaxes; decline of the contraction.
Patterns of contraction include what factors
- Frequency
- Duration
- Intensity
- Interval-resting tone
Frequency of contractions
The period from the beginning of one uterine contraction to the beginning of the next.
Frequency of contractions is expressed in
Minutes and fractions of minutes (i.e “contractions are 3 1/2 to 4 minutes apart”)
Resting tone needs to last how long for the baby to be reperfused?
Needs to last at least 60 seconds.
Duration of contractions
The length of each contraction from beginning to end.
How is duration of contractions expressed?
In seconds (i.e “her contractions last 55-65 seconds”)
What is the average duration of contractions?
About 2-4 minutes, lasting 60-90 seconds.
What is the purpose of contractions?
Is so that the cervix can dilate and she can deliver her baby.
Can’t deliver without contractions.
Intensity of contractions are described as
Mild, moderate or strong as palpated by the nurse.
Interval resting tone
- Period between the end of one contraction and the beginning of the next.
- Most fetal exchange of oxygen, nutrients and waste products occurs in the placenta at this time.
Uterine Body during labor: Upper 2/3
- The upper 2/3 of the uterus contracts actively to push the fetus down.
- Myometrial cells remain shorter at the end of each contraction.
Uterine Body during labor: Lower 1/3
- Remains less active, promoting downward passage of the fetus.
- Myometrial cells become longer with each contraction.
- Cervix is also passive.
Cervical changes during labor include
Effacement and dilation (occurs concurrently during labor but at different rates)
Cervical effacement in a nullipara
Completes most cervical effacement early in the process of cervical dilation
Cervical effacement in Paribus women
Cervix is usually thicker than that of a nullipara at any point during labor.
Nullipara
Woman who has never completed a pregnancy beyond a spontaneous or elective abortion.
Parous
Having given birth to one or more viable children.
Effacement
Thinning and shortening of the cervix.
Process of Effacement:
- Before labor the cervix is a cylindric structure about 2 cm long at the lower end of the uterus
- Labor contractions push the fetus downward against the cervix while pulling the cervix upward
- If the membranes are intact, hydrostatic (fluid) pressure of the amniotic sac adds to the force of the presenting part on the cervix
- As it is drawn over the fetus and amniotic sac the muscles of upper uterine segment shorten and cause cervix to thin and flatten
- The cervix merges with the thinning lower uterus rather than remaining a distinct cylindric structure
Effacement is estimated as
A percentage of the original cervical length.
A fully thinned cervix is
100% effaced
Effacement may also be documented as
The cervical length estimated during vaginal examination.
Dilation occurs as
The cervix is pulled upward and the fetus is pushed downward.
Full dilation is approximately
10 cm
What happens to HR during contraction?
- It increases.
- Also increase in CO d/t increased blood volume when blood flow is shunted back into mom’s circulation.
When is the best time to take vital signs in a woman during labor?
Between contractions because if you take VS during contraction, there is reduced blood flow to the uterus which temporarily increases maternal blood volume, CO and increases BP.
During each uterine contraction, blood flow to the placenta
Gradually decreases, causing a relative increase in the woman’s blood volume.
Respiratory system changes during labor
- Increase in oxygen demand and consumption
- Depth and rate of respiration increases, especially if the woman is anxious or in pain.
Respiratory system changes during the first stage of labor
Mom is going to hyperventilate as she starts to get a little bit uncomfortable d/t consistent, painful contractions -> leads to mild respiratory alkalosis**
What is important to do to help relieve mild respiratory alkalosis during the first stage of labor?
Calm the patient down and slow breathing.
Respiratory changes during the second stage of labor
At this stage, mom is pushing.
Mother tends to hold breath while pushing which can lead to mild respiratory acidosis**
Fetal response to mom pushing and holding her breath for a prolonged period of time can result in
Temporary mild fetal metabolic acidosis (typically reversible when baby takes first respiratory gasp of air after brith)