5. Powers, Psychological, Physiological Responses

what are the primary powers of labor?

uterine contractions

what are the secondary powers of labor?

maternal pushing and bearing down

• increase intra-abdominal pressure to help expel the fetus

how is contraction frequency measured?

beginning of one contraction → beginning of the next

how is contraction duration measured?

beginning → end of the same contraction

what is contraction intensity?

the strength of a contraction

can an external toco accurately measure contraction intensity?

NO, it records contraction frequency and duration, but not true strength

what measures contraction intensity directly in mm Hg?

an intrauterine pressure catheter (IUPC)

what does a mild contraction feel like on palpation?

the tip of the nose

what does a moderate contraction feel like on palpation?

the chin

what does a strong contraction feel like on palpation?

the forehead

what is resting uterine tone?

uterine pressure between contractions

what is the ideal resting uterine tone during labor? *

10–15 mm Hg

what contraction frequency raises concern for inadequate relaxation? *

contractions less than 2 minutes apart

what contraction duration raises concern and requires stopping an oxytocin infusion? *

longer than 60-90 seconds

contractions should NOT be more frequent than _____ and longer than _____, because thats too long for a fetus to be without perfusion

2 minutes; 60-90 seconds

why must the uterus relax between contractions? *

relaxation restores uteroplacental blood flow and fetal oxygen delivery

how can anxiety affect labor?

increases tension and pain and may interfere with labor progress

• reassurance and support help the patient cope

what happens to maternal HR, cardiac output, and BP during contractions?

they increase

• pain and the physical work of labor contribute

what happens to the maternal WBC count during labor?

it increases from the stress and tissue trauma of labor

• an elevated WBC count alone does not confirm infection

what happens to maternal respiratory rate and oxygen consumption during labor?

both increase

what happens to gastric function during labor?

motility, food absorption, emptying, and pH decrease

• nausea, vomiting, and aspiration risk increase

• dont usually feed mom during labor in hospital

what temperature change may occur during labor?

a slight increase from muscular activity

why may muscle aches and cramps occur during labor?

• stress on the muscles

• dehydration may worsen cramping

what happens to basal metabolic rate during labor?

it increases as energy demands rise

what happens to maternal blood glucose during labor?

it may decrease as energy is used

• monitor patients with diabetes for hypoglycemia

what is a fetal heart rate acceleration?

a temporary increase in FHR, often with fetal movement

• generally reassuring

what is a fetal heart rate deceleration?

a temporary decrease in FHR

• significance depends on the pattern and accompanying findings

when is a fetal heart rate deceleration more concerning?

when it is prolonged or accompanied by other abnormal FHR changes

fetal physiological responses to labor

• periodic fetal heart rate accelerations and slight decelerations

• decrease in circulation and perfusion

• increase in arterial carbon dioxide pressure

• decrease in fetal breathing movements

• decrease in fetal oxygen pressure

• decrease in partial pressure of oxygen

a healthy fetus usually _____ between contractions when FHR decreases

compensates