LEC 1: Factors Affecting Labour and Delivery Flashcards
What are the 6 P’s of Labour?
- Passage
- Passenger
- Position
- Powers
- Psychology
- People
The 6 P’s: Passage
- Maternal pelvis and soft tissues
- Ability of pelivs and cervis to accommodate passage of fetus
- Four clasical pelvis types:
- Gynecoid
- 50% of population
- Android
- Anthropoid
- 25% of population
- Platypelloid
- Gynecoid
What are the 4 classical pelvis types?
- Gynecoid
- 50% of population
- Android
- Anthropoid
- 25% of population
- Platypelloid

Gynecoid Pelvis
- Cnnsidered the true female pelvis
- Occurs in about 50% of all women
- Vaginal birth is most favourable with this type of pelvis because the inlet is round and the outlet is roomy
- The optimal diameters in all three planes of the pelvis
- Allows early and complete fetal internal rotation during labour
Anthropoid Pelvis
- Occurs in 25% of women
- The pelvic inlet is oval and the sacrum is long, producing a deep pelvis than side to side
- Vaginal birth is more favourable with this pelvic shape compared with the android or platypelloid shape
Android Pelvis
- Considered the male-shaped pelvis and is characterized by a funnel shape
- Occurs in around 20% of women
- THe pelvic inlet is heart-shaped and the posterior segments are reduced in all pelvic planes
- Desent of the fetal head into the pelvis is slow, and failure of the fetus to ritate is common
- The pronosis for labour is poor, subsequently leading ot cesaren birth
Platypelloid Pelivs
- The least common type of pelvic structure among men and women, with an approximate incidence of 5%
- The pelvic cavity is shallow but widen at the pelvic outlet, making it difficult for the fetus to descend through the midpelivs
- It is not favourable fir a vaginal birth unless the fetal head can pass through the inlet
- Women with this type of pelvis usually require cesarean birth
The 6 P’s: Passanger
- Fetus, membranes, placenta
- Ability of fetus to complete birth process
- Molding: Cranial bones overlap under pressure of the powers of labour and demands of unyielding pelvis
- The suboccipotobrematic comes out of the vagina first- smallest part of the head
- Even with the smallest diamete of the head coming out, there will still be molding
- The passage and the passanger need to work together
The 6 P’s: Position- Fetal Position
- Lie
- Refers to the relationship of fetal caphalocaudal axis (spine) to maternal cephalocaudal axis (spine)
Longitudinal, trasverse, oblique
- Attitude
- Relationship of fetal parts to one another
- Head can be extended, brow, flexed
- Presentation
- Determined by fetal lie and by body part of fetus that enters pelvic passage first; presenting part
- CEPHALIC = head
- Vertex, brow, face, chin (depending of attitude)
- BREACH = buttocks
- Complete, frank, incomplete
- SHOULDER - Shoulder is presented (cannot deliver vaginaly)
- COMPOUND - more than one body part is coming out at the same time
- Position
- Position of fetus in relation to pelvis
- R: Right
- L: Left
- O: Occiput
- S: Sacral
- M: Mentum
- Station
- Relationship of the presenting part (head, buttocks) to imaginary line drawn between ischial spines of maternal pelvis
- Head at 0 station is engaged
- Engagment: Largest diameter of presenting part reaches or passes through pelvic inlet
What are the different presentations?
- Cephalic
- Head
- Breach
- Buttokcks
- Shoulder
- Shoulder is presented
- Cannot deliver vaginaly
- Compound
- More than one body part coming out at the same time
The 6 P’s: Position- Maternal Position
- Certain maternal positions can promote comfort and enhance labour progress
- Repeated position change is often helpful
The 6 P’s: Powers
- Uterine contractions/ pushing
- Characteristics of contractions and effectivenss of expulsion methods
- Primary and secondary powers that work together ot achieve birht of fetus, fetal membranes, placenta
Primary Power
Uterine muscular contractions
Secondary Power
Use of abdominal muscles to push during second stage of labour
- Only asking to push during contractions
- Need to be fully dilated before pushing
- If not fully dilated can cause damage
Contractions
- Pressure of fetal head increases cervical dilation and effacement
- Woman experience a range of physical sensations- each deliver, each woman, each baby are unique
- Can range from very mild- menstraul carmp- to severe discomfort, some don’t feel any discomfort at all (rare)
Why do we need to assess contractions?
- Normal contractions decrease uteroplacental blood flow
- Most healthy fetuses tolerate this well
- Identify abdnomral contraction patterns that might adversely affect oxygen delivery to the fetus
How do we assess contractions?
- Timing
- How far apart, how ling, how strong are they, how many
- Frequency (Interval)
- Duration from start of one contraction to start of next (usally reported in minutes OR number of contractions/ 10 minutes)
- Duration (Length)
- From start to end (usually reported in seconds)
- Intesity (Strength)
- How strong are the contractions (weak, moderate, strong)
- Resting Tone of Uterus
- Important because it is a way to determine if there is a break between contractions so that the fetucs can be re-oxygenated
Acme
- Peak of contractins
- Fetal oxygenation is at risk for the fetus
The 6 P’s: Psychology
- Stress/ relaxation and progress
- Understanding and preparation for childbirth experience
- Hisotry and experiences
- Previous pregnancies
- This pregnancy
- Present emotional status
- Beleifs and values
- Age, general wellness
The 6 P’s: People
- Family, friends, healthcare, and providers
- Amount of support rom support persons
- Support from healthcare providers
- Types of suppoer (are they actually supportive?)
Premonitory Signs of Labour
- Lightinening
- Fetus descends into pelvid inlet
- Engaged
- Braxton Hicks Contractions
- Irregular, intermittent, ‘practice’ contractions that occur throughout pregnancy, painless, no cervical change
- Vaginal Mucous Increase
- Cervical Changes
- Cervix begins to soften and weaken (ripening)
- Bloody Show
- Loss of cervical mucous plug
- Causes blood-tinage discharge
- Rupture of Membranes
- If rupture prior to onset of labout in a term pregnancy
- Good change labour will begin within 24 hours
- Sudden Burst of Energy
- “Nesting”
- Usually occurs 24 to 48 hours before
- Loss of 0.5 to 1 kg
- Diarrhea, indigestion, nausea, vomiting
Differences Between True and Flase Labour
- Contraction Timing
- True Labour: Regular, becoming closer together, usually 4 to 6 minutes apart, lasting 30 to 60 seconds
- False Labour: Irregulat, not occuring close otgether
- Contraction Strength
- True Labour: Become stronger with time, vaginal pressure is usually felt
- False Labour: Frequently weak, not getting stronger with time or alternatin (a stron one followed by weker one)
- Contraction Discomfort
- True Labour: Starts in the back and radiates around toward the front of the abdomen
- False Labour: Contractions may stop or slow down with walking or making a position change
- Any Change in Activity
- Ture Labour: Contractions continue no matter what positional change is made
- False Labour: Contractions may stop or slow down with walking or making a position change
- Stay or go?
- True Labour: Stay home until contractions are 5 minutes apart, last 45 to 60 seconds, and are strong enough so that a conversation during one is not possible- then go to the hospital or birthing center
- False Labour: Drink fluids and walk around to see if there is any change in the intensity of the contractions; if the contractions diminish in intensity after either or both- stay home
First Stage of Labour: Cervical Dilation
-
Latent Phase → 0 to 3 cm
-
Physiological Changes
- Regular, mild contractions begin and increase in intensity and frequency (q5 to 10 hours)
- Cervical effiacement and dilation begin
- 0 to 3 cm
-
Psychological Changes
- Relief that labour has begun
- High excitement with some anxiety
- Important to differentiate from FALSE LABOUR
-
Physiological Changes
-
Active Phase → 4 to 7 cm
-
Physiologic Changes
- Contractions increase in intensity, frquency, and duration (q 2 to 5 hours)
- Cervical dilation 4 to 7 cm
- Fetus begins to descend into the pelvis
-
Psychological Changes
- Fear of loss of control
- Anxiety increases
-
Physiologic Changes
-
Transition Phase → 8 to 10 cm
-
Physiologic Changes
- Contractions increase in intensity, duration, and frequency
- Cervix thins and stretches to 8 to 10 cm
- Fetus descends rapidly into the birth passage
- Nausea and/or vomiting, diaphoretic, increased bloody show
-
Psychological Changes
- May experience trembling, restless, anxious, irritable, feeling overwhelmed or loss of control
-
Physiologic Changes
Physiological Changes of Labour
-
Cardiovascular
- Blood pressure increases each contraction
- May increase further with pushing
-
Respiratory
- Increase in oxygen demand and consumption
- Mild respiratory acidosis can occur time of birth
-
Gastrointestinal/ Genitourinary
- Edema in bladder due to pressure from fetal head
- Delayed gastric motility and fastric emptying
-
Hematological and Immune
- WBC increases
- Blood glucose decreases
Second Stage of Labour: 10 cm Dilatation to Birht of Infant
-
Physiologic Changes
- Pushing due to pressure of fetal head on nerves
- Woman uses intra-abdominal pressure to push
- Perineum bulge, flatten, move anteriorly as fetus descends
- Corwning- head visible,d oes not retract between contractions-pain
-
Psychological Changes
- May feel a sens of puprose
- Pushing may feel better than pressure
- May feel out of control, frightened, irritbale, panicky
- Tired and exhausted
Third Stage of Labour: 5 to 30 minutes: Delivery of Placenta
-
Physiologic Changes
- Placental separation
- Strong uterine contractions
- Lengthening of the cord
- Slight blood loss
- Uterus smaller, rounder and firmer
- Fundus rises in abdomen, harder an dincreased mobile
- Woman may feel pressure to bear down
- Placental delivery (may need slight cord traction)
-
Psychological Changes
- Relief at completion of birth
- Twilight
- Focus don welfare of baby
- May not recognize that placental expulsion is occuring
- Bounding
- Family time
Fourth Stage of Labour: Recovery and Stabilization: 1 to 4 Hours
-
Physiologic Changes
- Increased pulse and decreased blood pressure due to redistribution of blood from uterus and blood loss
- Uterus contracted btween imbilicus and symphysis pubis
- Woman may experience a shaking chill
- Urinary retention related to decreased bladder tone and possible trauma to the bladder
- Impact on uterus
-
Psychological Changes
- May be euphoric and neergized at birht of child
- May be TIRED
- Thirst and hungry
- Breastfeeding
- Bonding