NURS 405: Chapter 12? (Needs to be transferred) Flashcards
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
- Lightening
- Bloody Show
- Cervical Ripening
- Nesting
- Weight loss
Braxton Hick’s Contractions
….
Lightening
- 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
Nulliparas
Lightening occurs when?
About 2-3 weeks before the natural onset of labor**
Bloody Show
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.
Cervical ripening
Cervix begins to soften and weaken (ripening)
Nesting
- 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
Labor Mechanisms
Cardinal movements of labor occur as the fetus is moved through the pelvis during birth.
What are the labor mechanisms?
- Fetal position changes and descent through pelvis
2. Station