4.2a Factors affecting labor, passenger, pathway, power, position, psychology Flashcards
FACTORS AFFECTING LABOR
Passengers of Labor
- These include the fetus and placenta
Passageway of Labor
- Mothers birth canal
Powers of Labor
- Contractions
Position of Labor
- Mothers position
Psychology of Labor
- Psychologic Response
Passenger of Labor Factors
- How the baby moves through the birth canal determined by
- Size of fetal head
- Fetal presentation
- Fetal lie
- Fetal attitude
- Fetal position
Fetal Bones
- 2 Parietal
- 2 Temporal
- 1 Frontal
- 1 Occipital
These bones are connected by sutures
Fontanels are where more than 2 bones meet - Anterior fontanel is larger and diamond shaped (closes by 18 months)
- Posterior fontanel is smaller and closes within 6-8 weeks
Fetal Head
- After rupture of membranes palpation of these fontanels and sutures tells the fetal presentation, position and attitude.
- Sutures and fontanels make the skull flexible to accommodate the growing brain
MOLDING
- Slight overlapping of skull bones
Fetal Presentation
- The part of the fetus that leads through the birth canal
Cephalic Presentation - Head first (Occipital)
Breech Presentation - Butt/Feet first (Sacrum)
Shoulder presentation - Shoulder first (Scapula)
Fetal Lie
- How the babies spine lines up with the mothers spine
Longitudinal - Parallel
Transverse - At a right angle with mothers spine (cannot be birthed this way)
Oblique lie - Lying at an angle but usually converts to longitudinal during labor
Fetal Attitude
- Relation of fetal body parts to one another
Complications - Fetal head may be extended where it is too big to fit through maternal pelvis
(Prolonged labor, forceps, vacuum assisted birth, c-section) - Diameter of fetal head is measured by ultrasound
Biparietal Diameter
- Largest transverse diameter (widest part of head entering pelvic inlet)
Suboccipitobregmatic Diameter
- Smallest part of head entering pelvic pelvic inlet
- When head is in complete flexion it allows to pass through pelvis easily
Fetal Position
L - Left
R - Right
O - Occiput
S - Sacrum
M - Mentum (chin)
Sc - Scapula (shoulder
A - Anterior
P - Posterior
T - Transverse
Station
- Measures degree of descent of presenting part of baby through birth canal
- Measured above or below ischial spines
- Goes from -5 cm to +5 cm
- Leveled with the spine is = 0
- Birth imminent at +4 to +5
Engagement
- This is when the largest transverse diameter of presenting part has passed the maternal pelvic brim or inlet into the true pelvis (station 0)
- Determined by abdominal or vaginal examination
Passageway
- Composed of bones of pelvis, tissues of cervix, pelvic floor, vagina, introitus (opening of vagina)
- Muscle layers of pelvic floor play a large role in birth of fetus
- Pelvis plays large role in labor process
Pelvis
- Fusion of ileum, ischium, pubis, sacral bones
- False pelvis plays no role in birth
- True pelvis plays a role in birth
TYPES OF PELVIS
Gynecoid - Classic Female Pelvis
Android - Resembles Male Pelvis
Anthropoid - Oval shaped with larger Anteroposterior diameter
Platypelloid - Flat pelvis
Soft Tissue of Passageway
- Lower uterine segment
- Cervix
- Pelvic Floor Muscle
- Vagina
- Introitus
Powers of Delivery
Primary Powers
- Involuntary uterine contractions
- Signals the beginning of labor
- Responsible for effacement and dilation of cervix
FREQUENCY - Time from 1 contraction to the next
DURATION - Length of contraction
INTENSITY - Strength of contraction at its peak
Effacement
- Shortening and thinning of the cervix during 1st stage of labor
- Expressed as 0-100%
Dilation
- Widening of the cervical opening
- Increases from 1cm to 10cm
Ferguson Reflex
- Stretch receptors in vagina release oxytocin which triggers mother urge to bear down
Secondary Forces
- Voluntary (bearing down) efforts by mother
- Aids in expulsion of fetus
- Begins once fetus reaches pelvic floor
EXPULSIVE - involuntary urge to push
Position of Laboring Woman
- Frequent changes in position reduce fatigue, increase comfort, improve circulation
Psychology of Labor and Birth
- Enhanced through physical, emotional, social support
- Better social support has shown to reduce labor times, control pain better, less need for medication