The Labor Process

Front 1

A.
Initiation of labor:

comes about from an interplay of factors, including distension of uterus causing irritability and contractility, and hormonal influence of prostaglandins, oxytocin, fetal cortisol, estrogen, and progesterone

Back 1

B.
True versus false labor:

differentiated by cervical change: effacement and dilation

Front 2

C.
Factors of labor:

passageway, passenger (fetus), powers, and psyche

Back 2

C.1.
Passageway is maternal bony pelvis comprised of innominate bones (illium, ischium and pubis), sacrum and coccyx

Front 3

C.1.a.
False pelvis lies above pelvic brim, supports increasing weight of enlarging pregnant uterus, and directs presenting part into true pelvis below

Back 3

C.1.b.
True pelvis consists of inlet, midpelvis, and outlet and represents bony limits of birth canal; adequacy of each part, measured as transverse and anterior-posterior diameters, must be sufficient to allow passage of fetus through passageway

Front 4

C.1.c.
Four pelvic types:

gynecoid, android, anthropoid, and platypelloid

type of pelvis and its diameters influence descent of fetus, progression of labor, and type of delivery

Back 4

C.2.c.
Presentation - is fetal part entering pelvis first; most common presentation is cephalic, but breech and shoulder can also occur

Front 5

C.2.a.
Attitude - is the relationsip of fetal parts to one another; normal attitude is flexion of neck, arms, and legs

Back 5

C.2.b.
Lie - is relationsip of longitudinal axis of fetus to longitudinal axis of mother; vertex (head first) is most common, but breech (buttocks first), transverse (laterally across uterus), and oblique (diagonally across uterus) lies are possible

Front 6

2.d.
Position - is relationship of fetal presenting part to maternal pelvis; a three-letter notation is used to describe fetal position: the most common positions at delivery are ROA (right occiput anterior) and LOA (left occiput anterior)

Back 6

2.e.
Engagement - occurs when largest diameter of presenting part reaches pelvic inlet and can be detected by vaginal examination; termed floating if it is directed toward pelvis but can easily be moved out of inlet; termed ballotable when presenting part dips into inlet but can be displaced with upward pressure from examiner's fingers; termed engaged if fixed in pelvic inlet and cannot be displaced

Front 7

2.f.
Station - is relationship of presenting part to ischial spines of pelvis; measured in centimeters above (-1 to -5 station, at (0 station), or below (+1 to +4 station) the ischial spines

Back 7

3. Powers include the primary and secondary forces of labor

Front 8

3.a.
Primary forces consist of involuntary contractions of uterine muscle fibers, which are stimulated by a pacemaker located in upper uterine segment

Back 8

3.b.
Contractions consist of increment (building-up phase), acme (peak), and decdrement (letting-up phase) and are followed by a resting phase (nadir) to facilitate uteroplacental-fetal reoxygenation

Front 9

3.c.
Frequency of contractions is the time in seconds or minutes from onset of one contraction to onset of next

Back 9

3.d.
Intensity is strength of contraction at acme, which can be palpated as mild, moderate, or strong; detected with a fetal monitor externally; or measured internally in mm Hg

Front 10

3.e.
Duration is length of contraction measured in seconds from beginning of increment to end of decrement

Back 10

3.f.
With each contraction, muscles of upper uterine segment shorten and exert longitudinal traction on cervix, causing effacement, the thinning and drawing up of internal os and cervical canal into uterine side walls; measured from 0 to 100%; in primigravidas, effacement usually precedes dilation; in multigravidas, effacement and dilation normally occur simultaneously

Front 11

3.g.
As uterus elongates with contractions, fetal body straightens and exerts pressure against lower uterine segment and cervix; dilation, or opening of cervix, results, is measured from 0 to 10 cm, and allows for birth of fetus

Back 11

3.h.
Secondary powers consist of voluntary use of abdominal muscles during second stage of labor to facilitate descent and delivery of fetus

Front 12

4.
Psyche represents psychological component of childbearing; excitement, fear, perceived loss of control, and anxiety are common emotions during labor and birth process

Back 12

4.a.
Extreme emotions such as fear will result in muscular tension, which can create more pain from friction b/w working uterus and tense agdominal muscles or impede descent of fetus when pelvic and perineal muscles are tense rather than relaxed when pushing

Front 13

4.b.
Psyche can also be manifested physiologically as changes in maternal vital signs: inc. BP, pulse, and RR occur with fear, excitement, and anxiety

Back 13

4.c.
Lack of knowledge and preparation for childbirth can negatively affect psyche

Front 14

1.
R or L; direction that fetal presenting part of fetus faces

2.
AMOS: acromion process, mentum, occiput, sacrum; the landmark of the fetal presenting part

3.
PAT: posterior, anterior, transverse; the relationship of the landmark of the presenting part to the front, back, or side of the pelvis

Back 14

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