Ch.16 Labor and Birth Processes Lecture notes (completed)

What is the Passenger in the context of labor?

The movement of the fetus through the birth canal is determined by factors like fetal head size, fetal presentation, fetal lie, fetal attitude, and fetal position.

What is included in the Passageway during labor?

The Passageway is composed of the mother's rigid bony pelvis and the soft tissues of the cervix, pelvic floor, vagina, and introitus.

What are Primary Powers in labor?

Involuntary uterine contractions that signal the beginning of labor, responsible for effacement and dilation of the cervix.

What are Secondary Powers in labor?

Voluntary bearing-down efforts (pushing) by the mother that augment the force of the primary powers once the cervix is dilated.

How does the Position of the Laboring Woman affect labor?

The woman's position affects her anatomical and physiological adaptations to labor, with common positions including side-lying, upright, squatting, and the lithotomy position.

What is the Psychological Response in labor?

The mother's mental state, influenced by culture, expectations, past experiences, and support systems, affects her ability to cope with labor.

What is Fetal Presentation?

The part of the fetus that enters the pelvic inlet first and lies closest to the internal os of the cervix.

What is Cephalic Presentation?

Head first.

What is Breech Presentation?

Buttocks or feet first.

What is Shoulder Presentation?

The scapula is the presenting part.

Fetal Lie

The relation of the long axis (spine) of the fetus to the long axis of the mother, categorized as Longitudinal (parallel spines) or Transverse (right angle spines).

What is Fetal Attitude?

The relation of the fetal body parts to one another.

What is General Flexion in fetal positioning?

The fetus is curled into a 'ball' with the back rounded, chin on the chest, and thighs flexed on the abdomen, which is considered the normal posture for labor.

What is an Abnormal Attitude in fetal positioning?

Extension of fetal joints that can result in prolonged labor or the need for instrumental delivery.

What is Fetal Position?

The relationship of a reference point on the presenting part to the four quadrants of the mother's pelvis (e.g., Right Occipitoanterior - ROA, Left Occipitoposterior - LOP).

What are the reference points for fetal position?

Occiput (O) for vertex, Sacrum (S) for breech, Mentum (M) for face/chin, and Sinciput (Sc) for brow/forehead.

What is Station in relation to labor?

Station is the relationship of the presenting fetal part to an imaginary line drawn between the maternal ischial spines, measured in centimeters above or below the spines: -5 to -1 (above spines), 0 (at spines), and +1 to +5 (below spines/ne

What is Engagement?

Engagement occurs when the largest transverse diameter of the presenting part (usually the BPD) has passed through the pelvic inlet into the true pelvis, corresponding to a station of $0$.

True Pelvis

The lower part of the pelvis involved in childbearing, divided into the inlet (brim), mid-pelvis (cavity), and outlet.

False Pelvis

The shallow upper section above the pelvic brim; it does not play a part in childbearing.

Gynecoid Pelvis

The classic female pelvic type, found in approximately 50% of women.

Android Pelvis

Resembles the male pelvis, accounting for about 23% of cases.

Anthropoid Pelvis

Oval-shaped pelvis that is wider anteroposteriorly, found in 24% of women.

Platypelloid Pelvis

Flat pelvis type found in 3% of women, considered not ideal for childbirth.

What are Primary Powers (Involuntary)?

Involuntary uterine contractions responsible for effacement (shortening and thinning of the cervix) and dilation (enlargement of the cervical opening).

What is Frequency in relation to uterine contractions?

The time from the beginning of one contraction to the beginning of the next.

What is Duration in relation to uterine contractions?

The length of a single contraction from start to finish.

What is Intensity in relation to uterine contractions?

The strength of the contraction at its peak (acme).

What is the Primary Function of uterine contractions?

Responsible for effacement (the shortening and thinning of the cervix) and dilation (the enlargement of the cervical opening).

Secondary Powers

Invoked when the cervix is fully dilated (100% or 10 cm), these are voluntary 'bearing down' efforts by the mother to push the fetus through the birth canal.

What are the signs preceding labor?

Lightening (fetus dropping into the pelvis), lower back pain, and possible rupture of membranes (ROM).

What defines True Labor?

Regular contractions that induce progressive cervical changes (effacement and dilation).

How is False Labor characterized?

Irregular contractions with little or no cervical change.

What is the first stage of labor?

From the onset of regular contractions and effacement to full cervical dilation (6 cm).

What occurs during the second stage of labor?

From full cervical dilation (10 cm) to the birth of the fetus.

What happens in the third stage of labor?

From the birth of the fetus until the delivery of the placenta.

What is the fourth stage of labor?

The period following placenta delivery up to 2 hours after birth.

What is Engagement in the mechanism of labor?

The greatest diameter of the fetal head passes through the pelvic inlet.

What is Descent in the mechanism of labor?

The continuous movement of the fetus through the birth canal (measured by station).

What is Flexion in the mechanism of labor?

The fetal chin moves toward the chest as the head meets resistance from maternal tissues, presenting a smaller diameter to the outlet.

What is Internal Rotation in the mechanism of labor?

The fetal head rotates to exit the outlet, which is widest in the anteroposterior (AP) diameter.

What is Extension in the mechanism of labor?

The occiput passes under the symphysis pubis; the face and chin emerge from the vagina.

What is Restitution in the mechanism of labor?

Once the head is delivered, it rotates briefly to align with the back.

What is External Rotation in the mechanism of labor?

The shoulders rotate to align in the AP diameter of the pelvis.

What is Expulsion in the mechanism of labor?

The anterior shoulder emerges first, followed by the rest of the body.