week 1 chapter 16

Question 1

what are the 5 P’s that affect the process of labour and birth?

Answer 1

1. passenger (fetus and placenta),
2. passageway (birth canal),
3. powers (contractions),
4. position of the labouring patient, and
5. psychological response.

Question 2

what are the factors determining the movement of passenger?

Answer 2

the size of the fetal head, fetal presentation, fetal lie, fetal attitude, and fetal position.

the placenta also must pass through the birth canal, it can be considered a passenger along with the fetus; however, the placenta rarely impedes the process of labour in normal vaginal birth. An exception is the case of placenta previa

Question 3

the size of the fetal head

Answer 3

• major effect on the birth process
  The fetal skull is composed of two parietal bones, two temporal bones, the frontal bone, and the occipital bone
  -During labour, after the rupture of the membranes, palpation of the fontanels and sutures during vaginal examination reveals fetal presentation, position, and attitude.
  -The two most important fontanels are the anterior and posterior
  -because the bones are not firmly united, slight overlapping of the bones, or moulding of the shape of the head, occurs during labour.
  -Moulding can be extensive, but the heads of most newborns assume their normal shape within 3 days after birth.

Question 4

shoulders at birth

Answer 4

Although the size of the fetal shoulders may affect passage, their position can be altered relatively easily during labour so that one shoulder may occupy a lower level than the other. This creates a shoulder diameter that is smaller than the skull, facilitating passage through the birth canal. After the birth of the head and shoulders, the rest of the body usually emerges quickly.

Question 5

fetal presentation

Answer 5

Presentation refers to the part of the fetus that enters the pelvic inlet first and leads through the birth canal during labour at term.

Question 6

what are the 3 main fetal presentations?

Answer 6

The three main presentations are cephalic presentation
-(head first), occurring in 96% of births
-breech presentation (buttocks, feet, or both first), occurring in 3 to 4% of births
-and shoulder presentation, seen in less than 1% of births. The presenting part is that part of the fetus that lies closest to the internal os of the cervix.
-It is the part of the fetal body first felt by the examining finger during a vaginal examination. In a cephalic presentation, the presenting part is usually the occiput; in a breech presentation it is the sacrum; in the shoulder presentation it is the scapula.

Question 7

fetal lie

Answer 7

Lie is the relation of the long axis (spine) of the fetus to the long axis (spine) of the mother.

Question 8

what are the two fetal lies?

Answer 8

The two primary lies are longitudinal, or vertical, in which the long axis of the fetus is parallel with the long axis of the mother -and transverse, horizontal, or oblique, in which the long axis of the fetus is at a right angle diagonal to the long axis of the mother
-Longitudinal lies are either cephalic or breech presentations, depending on the fetal structure that first enters the mother’s pelvis.
-Vaginal birth cannot occur when the fetus stays in a transverse lie. An oblique lie, one in which the long axis of the fetus is lying at an angle to the long axis of the mother, is less common and usually converts to a longitudinal or transverse lie during labour

Question 9

fetal attitude

Answer 9

Attitude is the relation of the fetal body parts to one another. The fetus assumes a characteristic posture (attitude) in utero partly because of the mode of fetal growth and partly because of the way the fetus conforms to the shape of the uterine cavity. Normally, the back of the fetus is rounded so that the 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. This attitude is termed general flexion

Question 10

what happens if there is a deviation from the normal attitude?

Answer 10

for example, in a cephalic presentation, the fetal head may be extended or flexed in a manner that presents a head diameter that exceeds the limits of the maternal pelvis, leading to prolonged labour, forceps- or vacuum-assisted birth, or Caesarean birth.

Question 11

what is the biparietal diameter?

Answer 11

The biparietal diameter, which is about 9.25cm at term, is the largest transverse diameter and an important indicator of fetal head size
in a well-flexed cephalic presentation, the biparietal diameter is the widest part of the head entering the pelvic inlet. Of the several anteroposterior diameters, the smallest and the most critical one is the suboccipitobregmatic diameter (about 9.5cm at term)
- When the head is in complete flexion, this diameter allows the fetal head to pass through the true pelvis easily
-As the head is more extended, the anteroposterior diameter widens, and the head may not be able to enter the true pelvis

Question 12

the fetal position

Answer 12

The presentation or presenting part indicates the portion of the fetus that overlies the pelvic inlet. Position is the relationship of a reference point on the presenting part (occiput, sacrum, mentum [chin], or sinciput [deflexed vertex]) to the four quadrants of the mother’s pelvis

Question 13

fetal position and 3-letter abbreviation

Answer 13

-Position is denoted by a three-letter abbreviation. The first letter of the abbreviation denotes the location of the presenting part in the right (R) or left (L) side of the mother’s pelvis.
-Position is denoted by a three-letter abbreviation. The first letter of the abbreviation denotes the location of the presenting part in the right (R) or left (L) side of the mother’s pelvis.
-The third letter stands for the location of the presenting part in relation to the anterior (A), posterior (P), or transverse (T) portion of the maternal pelvis. For example, ROA means that the occiput is the presenting part and is located in the right anterior quadrant of the maternal pelvis

for ex., LSP means that the sacrum is the presenting part and is located in the left posterior quadrant of the maternal pelvis

Question 14

what is station?

Answer 14

Station is the relationship of the presenting fetal part to an imaginary line drawn between the maternal ischial spines and is a measure of the degree of descent of the presenting part of the fetus through the birth canal.
-The placement of the presenting part is measured in centimetres above or below the ischial spines

-when the lowermost portion of the presenting part is 1cm above the spines, it is noted as being minus (−) 1. At the level of the spines, the station is referred to as 0 (zero). When the presenting part is 1cm below the spines, the station is said to be plus (+) 1. Birth is imminent when the presenting part is at +4 to +5cm.

Question 15

what is engagement?

Answer 15

-Engagement is the term used to indicate that the largest transverse diameter of the presenting part (usually the biparietal diameter) has passed through the maternal pelvic brim or inlet into the true pelvis and usually corresponds to station 0.
-Engagement is the term used to indicate that the largest transverse diameter of the presenting part (usually the biparietal diameter) has passed through the maternal pelvic brim or inlet into the true pelvis and usually corresponds to station 0.

Question 16

the passageway

Answer 16

The passageway, or birth canal, is composed of the mother’s rigid bony pelvis and the soft tissues of the cervix, pelvic floor, vagina, and introitus (the external opening to the vagina).

Question 17

bony pelvis

Answer 17

The bony pelvis is formed by the fusion of the ilium, ischium, pubis, and sacral bones.
The four pelvic joints are the symphysis pubis, the right and left sacroiliac joints, and the sacrococcygeal joint

Question 18

the false pelvis

Answer 18

The false pelvis is the part above the brim and plays no part in childbearing.

Question 19

the true pelvis

Answer 19

The true pelvis, the part involved in birth, is divided into three planes: the inlet, or brim; the midpelvis, or cavity; and the outlet.

Question 20

the pelvic inlet

Answer 20

which is the upper border of the true pelvis, is formed anteriorly by the upper margins of the pubic bone, laterally by the iliopectineal lines along the innominate bones, and posteriorly by the anterior, upper margin of the sacrum and the sacral promontory.

Question 21

the pelvic cavity or midpelvis

Answer 21

is a curved passage with a short anterior wall and a much longer concave posterior wall. It is bounded by the posterior aspect of the symphysis pubis, the ischium, a portion of the ilium, the sacrum, and the coccyx.
The pelvic cavity varies in size and shape at various levels.

Question 22

the pelvic outlet

Answer 22

is the lower border of the true pelvis. Viewed from below, it is ovoid, somewhat diamond shaped, and bounded by the pubic arch anteriorly, the ischial tuberosities laterally, and the tip of the coccyx posteriorly
In the latter part of pregnancy, the coccyx is movable unless it has been broken and has fused to the sacrum during healing.

The diameters at the plane of the pelvic inlet, midpelvis, and outlet, plus the axis of the birth canal, determine whether vaginal birth is possible and the manner by which the fetus may pass down the birth canal.

Question 23

subpubic angle

Answer 23

The subpubic angle, which determines the type of pubic arch, together with the length of the pubic rami and the intertuberous diameter, is of great importance. Because the fetus must first pass beneath the pubic arch, a narrow subpubic angle is less accommodating than a rounded wide arch.

Question 24

what are the 4 basic types of pelves?

Answer 24

1.Gynecoid (the classic female type)-most common
2.Android (resembling the male pelvis)
3.Anthropoid (resembling the pelvis of anthropoid apes)
4.Platypelloid (the flat pelvis)-least common

Question 25

soft tissues during labour

Answer 25

-soft tissues of the passageway include the distensible lower uterine segment, cervix, pelvic floor muscles, vagina, and introitus.
-Before labour begins, the uterus is composed of the uterine body (corpus) and cervix (neck). After labour has begun, uterine contractions cause the uterine body to have a thick and muscular upper segment and a thin-walled, passive, muscular lower segment.
-A physiological retraction ring separates the two segments.
-The lower uterine segment gradually distends to accommodate the intrauterine contents as the wall of the upper segment thickens and its accommodating capacity is reduced.
-The contractions of the uterine body thus exert downward pressure on the fetus, pushing it against the cervix.
-The cervix effaces (thins) and dilates (opens) sufficiently to allow the first fetal portion to descend into the vagina. As the fetus descends, the cervix is actually drawn upward and over this first portion.

Question 26

pelvic floor

Answer 26

The pelvic floor is a muscular layer that separates the pelvic cavity above from the perineal space below. This structure helps the fetus rotate anteriorly as it passes through the birth canal. As noted earlier, the soft tissues of the vagina develop throughout pregnancy until at term the vagina can dilate to accommodate the fetus and facilitate its passage to the external world.

Question 27

primary powers

Answer 27

Involuntary uterine contractions, called the primary powers, signal the beginning of labour.
Terms used to describe these involuntary contractions include frequency (the time from the beginning of one contraction to the beginning of the next), duration (length of contraction), and intensity (strength of contraction at its peak).
The primary powers are responsible for the effacement and dilation of the cervix and descent of the fetus.

Question 28

secondary powers

Answer 28

Once the cervix has dilated, voluntary bearing-down efforts by the labouring patient, called the secondary powers, augment the force of the involuntary contractions.

the labouring patient experiences an involuntary urge to push. The patient uses secondary powers (bearing-down efforts) to aid in expulsion of the fetus as they contract their diaphragm and abdominal muscles and pushes. These bearing-down efforts result in increased intra-abdominal pressure that compresses the uterus on all sides and adds to the power of the expulsive forces.
-The secondary powers have no effect on cervical dilation, but they are of considerable importance in the expulsion of the newborn from the uterus and vagina after the cervix is fully dilated.

Question 29

Effacement

Answer 29

Effacement means the shortening and thinning of the cervix during the first stage of labour.

Question 30

dilation

Answer 30

-Dilation of the cervix is the enlargement or widening of the cervical opening and the cervical canal that occurs once labour has begun. The diameter of the cervix increases from less than 1cm to full dilation (approximately 10cm) to allow birth of a term fetus. When the cervix is fully dilated (and completely retracted), it can no longer be palpated.
-Full cervical dilation marks the end of the first stage of labour.

Question 31

how does dilation occur?

Answer 31

Dilation of the cervix occurs by the drawing upward of the musculofibrous components of the cervix, caused by strong uterine contractions. Pressure exerted by the amniotic fluid while the membranes are intact or by the force applied by the presenting part can promote cervical dilation. Scarring of the cervix as a result of prior infection or surgery may slow cervical dilation

Question 32

Ferguson reflex

Answer 32

When the presenting part of the fetus reaches the perineal floor, mechanical stretching of the cervix occurs. Stretch receptors in the posterior vagina cause the release of endogenous oxytocin that triggers the maternal urge to bear down, or the Ferguson reflex.

Question 33

positioning during labour

Answer 33

An upright position (walking, sitting, kneeling, or squatting) offers a number of advantages. Gravity can promote the descent of the fetus
-An upright position also is beneficial to the labouring patient’s cardiac output, which normally increases during labour as uterine contractions return blood to the vascular bed. The increased cardiac output improves blood flow to the uteroplacental unit and the maternal kidneys.

Question 34

the all 4 positions

Answer 34

the “all fours” position (hands and knees) may be used to relieve backache if the fetus is in an occipitoposterior position and may assist in anterior rotation of the fetus and in cases of shoulder dystocia.

Question 35

what is labour

Answer 35

The term labour refers to the process of moving the fetus, placenta, and membranes out of the uterus and through the birth canal.

Question 36

what are the signs preceding labour

Answer 36

*Lightening
*Return of urinary frequency
*Backache
*Stronger Braxton Hicks contractions
*Weight loss of 0.5 to 1.5kg
*Surge of energy (also called nesting)-Patients speak of having a burst of energy (nesting) that they often use to clean the house and put everything in order.
*Flulike symptoms
*Increased vaginal discharge; bloody show
*Cervical ripening
*Possible rupture of membranes

Question 37

first stage of labour

Answer 37

-The first stage of labour is considered to last from the onset of regular uterine contractions to full dilation of the cervix.
-The first stage is much longer than the second and third combined.
-Parity has a strong effect on the duration of first-stage labour. Full dilation may occur in less than 1 hour in some multiparous pregnancies. In first-time pregnancy, complete dilation of the cervix can take 18 hours or longer.
-The first stage of labour is divided into two phases: latent (early) and active labour

Question 38

what happens during latent (early) phase

Answer 38

During the latent phase, there is more progress in effacement of the cervix and little increase in descent.

Question 39

what happens during active labour phase?

Answer 39

During the active phase, there is more rapid dilation of the cervix and increased rate of descent of the presenting part.

Question 40

what happens during the second stage of labour

Answer 40

The second stage of labour lasts from the time the cervix is fully dilated to the birth of the fetus. It is composed of two phases: the latent phase (passive fetal descent) and the active pushing phase.

Question 41

2nd stage of pregnancy -the latent phase

Answer 41

During the latent phase the fetus continues to descend passively through the birth canal and rotate to an anterior position as a result of ongoing uterine contractions. The urge to bear down during this phase is not strong, and some labouring patients do not experience it at all.

Question 42

2nd stage of pregnancy -active pushing phase

Answer 42

During the active pushing phase the patient has strong urges to bear down as the presenting part of the fetus descends and presses on the stretch receptors of the pelvic floor.

Question 43

the third stage of labour

Answer 43

The third stage of labour lasts from the birth of the fetus until the placenta is delivered. The placenta normally separates with the third or fourth strong uterine contraction after the infant has been born. After it has separated, the placenta can be delivered with the next uterine contraction. Creating a warm environment, supporting skin-to-skin contact between mother and newborn, and reducing fear and anxiety contribute to decreased catecholamine production and increased oxytocin production, which facilitate placental separation. The duration of the third stage may be as short as 3 to 5 minutes, although up to 1 hour is considered within normal limits.

Question 44

the fourth stage of labour

Answer 44

The fourth stage of labour begins with the delivery of the placenta and includes at least the first 2 hours after birth. It is the period of immediate recovery, when homeostasis is re-established. The fourth stage of labour is also the time when parent–child bonding and attachment begins and breastfeeding is initiated. It is an important period of observation for complications, such as abnormal bleeding

Question 45

what are the seven cardinal movements of labour

Answer 45

The seven cardinal movements of the mechanism of labour that occur in a vertex presentation are engagement, descent, flexion, internal rotation, extension, external rotation (restitution), and, finally, birth by expulsion.
Although these movements are discussed separately, in actuality a combination of movements occurs simultaneously.

Question 46

engagement

Answer 46

When the biparietal diameter of the head passes the pelvic inlet, the head is said to be engaged in the pelvic inlet.
-In most nulliparous pregnancies, this occurs before the onset of active labour because the firmer abdominal muscles direct the presenting part into the pelvis.
-In multiparous pregnancies in which the abdominal musculature is more relaxed, the head often remains freely movable above the pelvic brim until labour is established.

Question 47

asynclitism

Answer 47

The head usually engages in the pelvis in a synclitic position (i.e., one that is parallel to the anteroposterior plane of the pelvis). Frequently, asynclitism occurs (the head is deflected anteriorly or posteriorly in the pelvis), which can facilitate descent because the head is being positioned to accommodate to the pelvic cavity
-Extreme asynclitism can cause cephalopelvic disproportion, even in a normal-size pelvis, because the head is positioned so that it cannot descend

Question 48

decent

Answer 48

Descent refers to the progress of the presenting part through the pelvis. Descent depends on at least four forces:
(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 labour, and
(4) extension and straightening of the fetal body.

Descent accelerates in the active phase. In a first-time labour, descent is usually slow but steady; in subsequent pregnancies, descent may be rapid.

Question 49

flexion

Answer 49

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. Flexion permits the smaller suboccipitobregmatic diameter (9.5cm) rather than the larger diameters to present to the outlet.

Question 50

internal rotation

Answer 50

The maternal pelvic inlet is widest in the transverse diameter; therefore, the fetal head passes the inlet into the true pelvis in the occipitotransverse position. The outlet is widest in the anteroposterior diameter; in order for the fetus to exit, the head must rotate. 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. With each contraction the fetal head is guided by the bony pelvis and the muscles of the pelvic floor. Eventually, the occiput will be in the midline beneath the pubic arch. The head is almost always rotated by the time it reaches the pelvic floor

Question 51

extension

Answer 51

When the fetal head reaches the perineum for birth, it is deflected anteriorly by the perineum. The occiput passes under the lower border of the symphysis pubis first, and then the head emerges by extension: first the occiput, then the face, and finally the chin

Question 52

restitution and external rotation

Answer 52

After the head is born, it rotates briefly to the position it occupied when it was engaged in the inlet. This movement is referred to as restitution. The 45-degree turn realigns the newborn’s head with their back and shoulders. The head can then be seen to rotate further. This external rotation occurs as the shoulders engage and descend in manoeuvres similar to those of the head

Question 53

Expulsion

Answer 53

After birth of the shoulders, the head and shoulders are lifted up toward the mother’s pubic bone, and the trunk of the baby is born by flexing it laterally in the direction of the symphysis pubis. When the baby has completely emerged, birth is complete, and the second stage of labour ends.

Question 54

fetal heart rate

Answer 54

Fetal health surveillance (FHS) provides information about the condition of the fetus related to oxygenation. The average FHR at term is 110 to 160 beats/min. Earlier in gestation the FHR is higher, with an average of approximately 160 beats/min at 20 weeks of gestation.

Question 55

fetal circulation

Answer 55

Fetal circulation can be affected by many factors, including maternal position, uterine contractions, blood pressure, and umbilical cord blood flow. Uterine contractions during labour tend to decrease circulation through the spiral arterioles and subsequent perfusion through the intervillous space.
Most healthy fetuses are able to compensate for this stress and exposure to increased pressure while moving passively through the birth canal during labour

Question 56

Fetal Respiration

Answer 56

certain changes stimulate chemoreceptors in the aorta and carotid bodies to prepare the fetus for initiating respirations immediately after birth
-These changes include the following:
*Fetal lung fluid is cleared from the air passages as the newborn passes through the birth canal during labour 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 labour.

Question 57

Physiological Changes in Patient During Labour

Answer 57

*Cardiac output increases 10 to 15% in first stage; 30 to 50% in second stage.
*Heart rate increases slightly in first and second stages.
*Systolic and diastolic blood pressure increase during uterine contractions and return to baseline between contractions. Systolic values increase more than diastolic values.
*White blood cell count increases.
*Respiratory rate increases.
*Temperature may be slightly elevated.
*Proteinuria may occur.
*Gastric motility and absorption of solid food are decreased; nausea and vomiting may occur during the active phase to second-stage labour.
*Blood glucose level decreases.

Question 58

respiratory changes

Answer 58

Increased physical activity with greater oxygen consumption is reflected in an increase in the respiratory rate. Hyperventilation may cause respiratory alkalosis (an increase in pH), hypoxia, and hypocapnia (decrease in carbon dioxide). In the unmedicated labouring patient in the second stage, oxygen consumption almost doubles. Anxiety also may increase oxygen consumption.

Question 59

renal changes

Answer 59

During labour, spontaneous voiding may be difficult for various reasons: tissue edema caused by pressure from the presenting part, discomfort, analgesia, and embarrassment. Proteinuria up to +1 is a normal finding because it can occur in response to the breakdown of muscle tissue from the physical work of labour.

Question 60

integumentary changes

Answer 60

The integumentary system changes are evident, especially in the great distensibility (stretching) in the area of the vaginal introitus. The degree of distensibility varies with the individual. Despite this ability to stretch, even in the absence of episiotomy or lacerations, minute tears in the skin around the vaginal introitus occur.

Question 61

musculoskeletal changes

Answer 61

The musculoskeletal system is stressed during labour. Diaphoresis, fatigue, proteinuria (+1), and possibly an increased temperature accompany the marked increase in muscle activity. Backache and joint ache (unrelated to fetal position) occur as a result of increased joint laxity at term. The labour process itself and the patient’s pointing their toes can cause leg cramps.

Question 62

neurological changes

Answer 62

Sensorial changes occur as the patient moves through phases of the first stage of labour and from one stage to the next. Initially, the patient may be euphoric.
Euphoria gives way to increased seriousness, to amnesia between contractions during the second stage, and finally to elation or fatigue after giving birth. Endogenous endorphins (morphine-like chemicals produced naturally by the body) raise the pain threshold and produce sedation. In addition, physiological anaesthesia of perineal tissues, caused by pressure of the presenting part, decreases the perception of pain.

Question 63

gastrointestinal changes

Answer 63

During labour, gastrointestinal motility and absorption of solid foods are decreased, and stomach-emptying time is slowed. Nausea and vomiting of undigested food eaten after onset of labour are common. Nausea and belching also occur as a reflex response to full cervical dilation. The patient may state that diarrhea accompanied the onset of labour, or the nurse may palpate the presence of hard or impacted stool in the rectum. If stool is present in the rectum the patient often passes this as they push.

Question 64

endocrine changes

Answer 64

The onset of labour may be triggered by decreasing levels of progesterone and increasing levels of estrogen, prostaglandins, and oxytocin. Metabolism increases, and blood glucose levels may decrease with the work of labour. Patients who are diabetic require close monitoring of glucose levels during labour

Question 65

valslva manoueuvre

Answer 65

The patient should be discouraged from using the Valsalva manoeuvre (holding one’s breath and tightening abdominal muscles) for pushing during the second stage. This activity increases intrathoracic pressure, reduces venous return, and increases venous pressure. Cardiac output and blood pressure increase, and the pulse slows temporarily. During the Valsalva manoeuvre, fetal hypoxia may occur. The process is reversed when the patient takes a breath.

Question 66

cardiovascular changes

Answer 66

During each contraction, an average of 300 to 500mL of blood is shunted from the uterus into the maternal vascular system. By the end of the first stage of labour, cardiac output during contractions is increased up to 51% above baseline pregnancy values at term. Cardiac output peaks about 10 to 30 minutes after both vaginal and Caesarean birth and returns to its prelabour baseline within the first postpartum hour. A drop in maternal heart rate accompanies this increase in cardiac output.
Changes in blood pressure also occur. Blood flow, which is reduced in the uterine artery by contractions, is redirected to peripheral vessels. As a result, peripheral resistance increases and blood pressure increases. In general, both systolic and diastolic pressures increase during contractions and return to baseline levels between contractions. Assessing blood pressure between contractions provides more accurate readings.

Question 67

supine hypotension

Answer 67

occurs when the ascending vena cava and descending aorta are compressed. The labouring patient is at greater risk for supine hypotension if the uterus is particularly large because of multifetal pregnancy, hydramnios, or obesity or if the patient is dehydrated or hypovolemic. In addition, anxiety, pain, and some medications can cause hypotension.