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Chapter 12: Processes of Birth
Physiologic Effects of the Birth Process: Maternal Response
→Most obvious changes of pregnancy and birth occur in the woman’s reproductive system, but significant changes also occur during labor in her cardiovascular, resp, GI, urinary, and hematopoietic systems
Reproductive System: Characteristics of Contractions
▪ Coordinated o Uterus can contract and relax in a coordinated way o If not coordinated=not effective o Frequency (beginning of one uterine contraction to the beginning of the next) ▪ Frequency be assessed as the # of contractions in 10 minutes, averaged over 30 minutes o Duration (beginning of a uterine contraction to the end of the same contraction) ▪ Usually expressed in seconds o Intensity (strength of a contraction) ▪ Mild, moderate, and strong → describe contraction intensity as palpated by the nurse ▪ Different descriptions of intensity apply when an internal fetal monitor is used to record contractions o Coordinated labor contractions begin in the uterine fundus and spread downward toward the cervix to propel the fetus through the pelvis ▪ Involuntary o Uterine contractions are involuntary and are not under conscious control o Anxiety and excessive stress can diminish contractions, whereas relaxation can facilitate the natural process ▪ Intermittent (come &go) o Are intermittent rather than sustained, allowing relaxation of the uterine muscle and resumption of blood flow to and from the placenta
▪ Contractions last 60-90 seconds, 2-3 minutes apart
▪ Coordinated contractions from the top thin and dilate the cervix Reproductive System: Contraction Cycle (3 parts)
- Increment (period of increasing strength) a. Occurs as the contraction begins in the fundus and spreads throughout the uterus
- Acme (peak) (period during which the contraction is most intense ) 3) Decrement (period of decreasing intensity as the uterus relaxes)—comes back down to softer uterus
Contraction Cycle
▪ Interval →the period b/w the end of one contraction and the beginning of the next o Most fetal exchange of oxygen, nutrients, and waste products occurs in the placenta at this time!
▪ Strips on test, know: baseline FHR, how far apart they are, have
reactivity or not, decelerations (what type: early, late, variable)
Reproductive System: Uterine Body
▪ The upper two thirds of the uterus contracts actively to push the fetus down. o Upper uterus becomes thicker as lower uterus becomes thinner and is pulled upward during labor ▪ The lower one third of the uterus remains less active, promoting downward passage of the fetus ▪ The cervix is also passive. ▪ Myometrial (pertaining to the uterine muscle) cells in the upper uterus remain shorter at the end of each contraction rather than returning to their original length
▪ Hyperventilation
o It may occur with rapid and deep breathing. ▪ Use brown paper bag to get CO2 back o Respiratory alkalosis occurs as she exhales too much carbon dioxide. ▪ She may feel tingling of her hands and feet, numbness, and dizziness.
▪ The nurse should help her slow her breathing and breathe into a paper
bag or her cupped hands to restore normal blood levels of carbon dioxide
and relieve these symptoms.
Maternal Gastrointestinal System
▪ Decreased gastric motility --- can result in N/V ▪ Most women are not hungry but are thirsty and have dry mouths. o Ice chips are commonly provided. o Small amounts of other clear liquids may be allowed. ▪ Solid food is usually withheld to prevent vomiting and aspiration in the event that general anesthesia is required. Maternal Urinary System
▪ Reduced sensation of a full bladder ---b/c of intense contractions and the effects of regional anesthesia, the woman may be unaware that her bladder is full, yet it may contribute to discomfort, especially that which persists after regional anesthesia ▪ Full bladder can inhibit fetal descent b/c is occupies space in the pelvis Maternal Hematopoietic System ▪ 500 mL normal blood loss for vaginal delivery
o Women can tolerate profuse blood loss during the birthing
process because of the ↑ blood volume during pregnancy by
▪ Woman who is anemic at the beginning of labor has less reserve for normal blood loss and poor tolerance for excess bleeding ▪ Levels of several clotting factors, especially fibrinogen, are elevated during pregnancy and continue to be higher during labor and after delivery. o Provides protection from hemorrhage o Increases the mother’s risk for a venous thrombosis during pregnancy and after birth
▪ DVT ↑ w/ bed rest
Physiologic Effects of the Birth Process: Fetal Response
▪ Placental circulation
o Exchange of oxygen, nutrients, and waste products b/w the mother and fetus occurs in the intervillous spaces without the mixing of maternal and fetal blood o During strong labor contractions, the maternal blood supply to the placenta ↓ and eventually stops temporarily as the spiral arteries supplying the intervillous spaces are compressed by the uterine muscle
o Most placental exchange occurs during the interval between contractions
o Fetal protective mechanisms include: ▪ Fetal hGB, which more readily takes on oxygen and releases carbon dioxide ▪ High hGB and Hct levels than can carry more oxygen than adult hGB ▪ A high cardiac output
▪ Cardiovascular system responds to stress
o Heart rate ranges from 110 to 160 beats per minute (BPM)
▪ Pulmonary system
o The fetal lungs produce fluid to allow normal development of the airways. o As term nears, production of fetal lung fluid decreases to about 65% of its maximum production and its absorption into the interstitium of the lungs ↑ o Labor speeds the absorption of lung fluid, so about 35% of the maximum amount remains in the airways at birth
▪ Some fluid is expelled from the upper airways as the fetal
head and thorax are compressed during passage through
the birth canal
▪ Most remaining lung fluid is absorbed into the interstitial spaces of the newborn’s lungs and then into the circulatory system
Components of the Birth Process: Powers
▪ Uterine contractions (1st^ stage of labor) o Primary force that moves the fetus through the maternal pelvis
▪ Maternal pushing efforts (2nd^ stage of labor)→ accelerate movements
o Full cervical dilation to birth of the baby o Uterine contractions continue to propel the fetus through the pelvis o Woman feels an urge to push and bear down as the fetus distends her vagina and puts pressure on her rectum. Components of the Birth Process: Passage ▪ The bony pelvis o Usually more important to the outcome of labor than the soft tissue b/c the bones and joints do not readily yield to the forces of labor. o However, softening of the cartilage linking the pelvic bones occurs near term b/c in ↑levels of the hormone relaxin ▪ The linea terminalis (pelvic brim) divides the bony pelvis into the: o False pelvis (top) above linea terminalis o True pelvis (bottom) below linea terminalis ▪ Most important in childbirth (has 3 subdivisions):
- Inlet (upper pelvic opening)
- Midpelvis (pelvic cavity) (zero station= even w/ the ischial spin) 3) Outlet (lower pelvic opening) (coming out of pelvis) Components of the Birth Process: Passenger ▪ The passenger is the fetus, membranes, and placenta. ▪ Several fetal anatomic and positional variables influence the course of labor.
▪ Fetal head
o Cephalic presentation (96% of the time) o The bones of the fetal head involved in the birth process are: ▪ The two frontal bones on the forehead ▪ Two parietal bones at the crown of the head ▪ Occipital bone at the back of the head ● The five major bones are not fused but are connected by sutures which are narrow areas of flexible tissue that connect fetal skull bones, permitting slight movement during labor
o Fontanels
▪ Wider spaces at the intersections of the sutures connecting fetal or infant skull bones
▪ Anterior fontanel diamond shape
● Formed by the intersection of four sutures: o Two coronal, frontal, and sagittal, which connect the 2 frontal and 2 parietal bones
▪ Posterior fontanel triangular shape
● Formed by the intersection of 3 sutures o One sagittal and two lambdoid, which connect the two parietal bones and occipital bone ● Very small, and often looks more like a slight indentation in the skull
→The sutures and different shapes of the fontanels provide important landmarks to determine fetal position (relation of a fixed reference point on the fetus to the quadrants of the maternal pelvis) and head flexion during vaginal examination
o Fetal head diameters ▪ 9.5cm ▪ Components of the Birth Process: Passenger (Cont.)
4) Face
● Head is extended and the fetal occiput is near the fetal spine. The submentobregmatic diameter is presenting
o Breech
▪ Occurs when the fetal buttocks enter the pelvis first ▪ More common in preterm births and when a fetal abnormality such as hydrocephalus prevents the head from entering the pelvis during the later weeks of pregnancy or with abnormalities of the maternal uterus and pelvis with placenta previa (placenta in the lower uterus)
▪ Disadvantages:
● Buttocks are not smooth and firm like the head and are less effective at dilating the cervix ● Fetal head is the last part to be born, by the time the fetal head is deep in the pelvis, the umbilical cord is outside the mother’s body and is subject to compression b/w the fetal head and the maternal pelvis ● Head must be delivered quickly to allow infant to breathe ▪ Frank : most common variation, occurring when the fetal legs are extended across the abdomen toward the shoulders ▪ Full : (complete breech) Indian style/ bottom down—head, knees, and hips are flexed, but the buttocks are presenting ▪ Footling : one foot or both feet are out
o Shoulder
Cephalic Presentation
▪ Cesarean birth is necessary when the fetus is viable ▪ Occurs more often w/ preterm birth, high parity, prematurely ruptured membranes, hydramnios, and placenta previa
Breech Presentation
Components of the Birth Process:Variations in the Passenger (Cont.)
▪ Position
o Location of fixed reference point on the presenting part in relation to the four quadrants of the maternal pelvis
o Right or left
▪ First letter of the abbreviation describes whether the fetal reference point is to the right or left of the mother’s pelvis. If the fetal reference point is neither to the right nor to the left of the pelvis, this letter is omitted
o
o Transverse (T)
▪ If the fetal reference point is in neither an anterior nor a posterior quadrant
▪ Don’t feel baby presenting parts= deliver C-section
o LOA,ROA,LOP,ROP,LSA,RSA
Components of the Birth Process: Psyche→psychological response to labor
▪ Anxiety
Posterior (P)
o Maternal catecholamine’s secreted in response to anxiety and fear can inhibit uterine contractility and placental blood flow ▪ Culture and expectations
▪ True Labor
o Increased contractions o Increased discomfort o ***Cervical change: progressive effacement and dilation most important ▪ DILATION
▪ False labor (prodromal labor or prelabor)
o Contractions inconsistent/ uncoordinated o Discomfort is more annoying than truly painful o Cervix does not change ▪ NO dilation Normal Labor: Labor Mechanisms
▪ Descent
o Movement of fetus through the birth canal ▪ Abdomen-pelvis- birth canal
o Inhibiting factors: ▪ Full bladder can inhibit fetal descent b/c it occupies space in pelvis= UTERINE ATONY causing HEMORRHAGE! ▪ Small pelvis, position of baby (brow/face/ shoulder) large baby, ineffective contractions
▪ Engagement
o Occurs when the largest diameter of the fetal presenting part (normally the head) pas passed the pelvic inlet and entered the pelvic cavity o Fetal presenting part reaches 0 station ▪ Ears at ischial spine
▪ Internal rotation
o Rotates head at different position – to allow the largest fetal head diameters to align w/ the largest maternal pelvic diameters
o The fetus enters the pelvic inlet w/ the sagittal suture in a
transverse or oblique orientation to the maternal pelvis b/c that is the widest inlet diameter o Internal rotation allows the longest fetal head diameter (the anteroposterior) to conform to the longest diameter of the maternal pelvis
▪ Flexion
o Of the fetal head, allowing the smallest head diameters to align w/ the smaller diameters of the midpelvis as the fetus descends
▪ Extension
o Extending up, start to see crowning (HAIR)
▪ External rotation
o Head is out an rotates to one side o Aligning the head w/ the shoulders during expulsion
▪ Expulsion
o Head is completely out- should deliver
Normal Labor: Stages of Labor
▪ First stage of labor (0-10) onset of true labor
o Latent phase---(7.3-8.6hrs)(O-3cm)
▪ Cervical dilation and effacement
▪ Educate** , FHR
▪ Cervical effacement and fetal positional change occur during the latent phase, preparing for the more rapid changes of active labor ▪ Happy ▪ Transfers from latent to active when she needs an epidural ▪ Start of dilation
▪ Anxiety ↑fear of losing control helplessness “I can’t do this”
▪ Contractions every 1.5-2 minutes lasting 60-90 seconds- strong
intensity
▪ Averaging 3.6 hours in the nullipara and having a variable length in the multipara
▪ Second stage of labor
o Expulsion of the fetus o “expulsion” begins w/ complete (10cm) dilation and full (100%) effacement of the cervix and ends w/ the birth of the baby o The word “labor” aptly describes the second stage o Pushing & Delivery of the baby o May think she needs to have a bowel movement or “the baby is coming”/ “I have to push”
o DON’T PUSH IF NOT AT 10 CM---otherwise cervix will swell and not be
able to deliver
o *pushing techniques ▪ Bare down as if you’re having a bowel movement ▪ Can push even w/ epidural o Contractions may diminish slightly or even pause briefly as the second stage begins
▪ They are still strong, about 2 to 3 minutes apart, with a duration of
40-60 seconds
▪ Third stage of labor (shortest stage) o Expulsion of the placenta o Begins with the birth of the baby and ends with the expulsion of the placenta o Shortest stage, with an avg length of 6 minths o When the infant is born, the uterine cavity becomes much smaller o The reduced size decreases the size of the placenta site, causing it to separate from the uterine wall o Four signs suggest placenta separation:****
1) Uterus has a spherical shape
2) Uterus rises upward in the abdomen as the placenta descends into the vagina and pushed the fundus upward
3) Cord descends further from the vagina
4) A gush of blood appears as blood trapped behind the placenta is released o Mechanisms: ▪ Schultze : placenta is expelled with the shiny fetal side presenting first ▪ Duncan : rough maternal side presents first o Delivery of placenta (avg 6 mins) o The uterus must contract firmly and remain contracted after the placenta is expelled to compress open vessels at the implantation site o Monitor for hemorrhage ▪ Soft boggy uterus (uterine atony) ● Massage uterus supporting suprapubic area ● Encourage to pee Q3Hrs
▪ Fourth stage of labor (recovery period 1 - 4hrs after birth)
o Maternal physiologic stabilization and parent—infant bonding o Immediately after birth, the firmly contracted uterus can be palpated through the abdominal wall as a firm, rounded mass about 10-15 cm in diameter at or below the level of the umbilicus o Monitor for hemorrhage o Educate (reinforce) o Hydrate o Assessments essential (VS)
▪ If multipara contractions 10 minutes apart in an hour, come to hospital
▪ If primipara 5 minutes apart in an hour, come to hospital
▪ If ferning present, that means ROM (rupture of membranes)
Stages of Labor
Normal Labor:
● FHR Q30min ● Contractions Q30min ● Active phase: o FHR Q15min o Contractions Q30min
