Labor and Birth Process

Vocabulary practice flashcards covering maternal health nursing concepts from Unit 4: factors affecting labor (the Five P's), fetal lie, presentation, attitude, station, cranial dimensions, powers, stages of labor, and the cardinal movements of labor.

The Five P's

The major critical factors that determine and affect the labor and birth process: Passenger (fetus and placenta), Passageway (birth canal), Powers (contractions and bearing down), Position of the laboring woman, and Psychological response.

Passenger

The fetus and the placenta moving through the birth canal, whose progression is influenced by the size of the fetal head, fetal presentation, fetal lie, fetal attitude, and fetal position.

Fetal Cranial Sutures and Fontanels

The membranous spaces and joints connecting the cranial bones (frontal, parietal, occipital, temporal) of the fetal skull—including the coronal, sagittal, lambdoid, and frontal sutures, as well as the anterior and posterior fontanels—that allow the skull bones to overlap and mold during labor.

Fetal Presentation

The part of the fetus that enters the maternal pelvic inlet first and leads through the birth canal during labor, categorized as cephalic/vertex (sinciput, brow), transverse (shoulder), or breech (frank, complete, footling).

Fetal Lie

The relationship of the long axis (spine) of the fetus to the long axis (spine) of the mother, classified as either longitudinal (vertical) or transverse (horizontal).

Frank Breech

A breech presentation occurring with a longitudinal or vertical lie, characterized by flexion of the hips, extension of the legs at the knees with feet near the head, and the sacrum as the presenting part.

Single Footling Breech

An incomplete breech presentation with a longitudinal or vertical lie where the sacrum is the presenting part and one leg is extended at the hip and knee into the birth canal.

Complete Breech

A breech presentation with a longitudinal or vertical lie where the fetus is in general flexion, with both hips and knees flexed, and both the sacrum and feet present at the cervix.

Shoulder Presentation

A fetal presentation occurring with a transverse or horizontal lie where the fetal scapula is the presenting part at the pelvic inlet.

Fetal Attitude

The relationship of the fetal body parts to one another, typically characterized by general flexion where the chin is flexed onto the chest, thighs flexed on the abdomen, and arms crossed over the thorax.

Suboccipitobregmatic Diameter

The smallest anteroposterior diameter of the fetal skull, measuring approximately $9.5\,\text{cm}$, which presents to the maternal pelvis when the fetal head is in complete flexion (vertex presentation).

Occipitofrontal Diameter

The anteroposterior diameter of the fetal head measuring approximately $12\,\text{cm}$, presenting when the head is in moderate flexion (sinciput presentation).

Occipitomental Diameter

The largest anteroposterior diameter of the fetal skull, measuring approximately $13.5\,\text{cm}$, which presents to the pelvis when the fetal head is extended (brow presentation).

Biparietal Diameter

The widest transverse diameter of the fetal skull, measuring approximately $9.25\,\text{cm}$, critical for determining whether the fetal head can pass through the pelvic inlet.

Fetal Position

The relationship of a reference point on the fetal presenting part to the maternal pelvis, designated using a three-letter abbreviation system indicating right (R) or left (L), the presenting part (O, S, M, Sc), and orientation (Anterior [A], Posterior [P], or Transverse [T]).

Occiput (O)

The anatomical reference point representing the back of the fetal skull, used in cephalic or vertex presentations within the three-letter positioning system.

Sacrum (S)

The anatomical reference point on the fetal pelvis used to designate fetal position in breech presentations within the three-letter positioning system.

Mentum (M)

The anatomical reference point representing the fetal chin, used in face presentations within the three-letter positioning system.

Scapula (Sc)

The anatomical reference point representing the fetal shoulder, used in transverse lie presentations within the three-letter positioning system.

Station

The measurement of fetal descent through the birth canal, defined as the relationship of the presenting fetal part to an imaginary line between the maternal ischial spines; designated as station $0$ at the level of the spines, negative ($-1$ to $-5\,\text{cm}$) above, and positive ($+1$ to $+5\,\text{cm}$) below.

Passageway

The maternal birth canal consisting of the rigid bony pelvis and the soft tissues of the cervix, pelvic floor muscles, vagina, introitus, and adjacent structures.

Introitus

The external orifice of the vagina that forms part of the soft-tissue passageway through which the fetus emerges during delivery.

Primary Powers

Involuntary uterine muscle contractions that cause cervical effacement, cervical dilation, and stimulate the Ferguson reflex during labor.

Effacement

The progressive shortening, thinning, and drawing up of the cervix that occurs during the first stage of labor.

Dilation

The widening and enlargement of the cervical os and canal during the first stage of labor, progressing from closed to full dilation ($10\,\text{cm}$).

Ferguson Reflex

The maternal involuntary urge to bear down, triggered by stretch receptors in the posterior vagina when the presenting fetal part stretches the pelvic floor muscles.

Secondary Powers

The voluntary, bearing-down muscular efforts (pushing) performed by the laboring woman during the second stage of labor to aid in fetal expulsion.

External Powers

Forces originating outside maternal physiology that assist in labor progression, specifically gravity and medical interventions.

Maternal Position Changes

Frequent alterations in maternal posture during labor that relieve physical fatigue, enhance comfort, improve maternal-fetal circulation, and facilitate anatomical and physiological adaptations.

Lightening

A premonitory sign of labor occurring days to weeks before onset, in which the presenting part of the fetus drops down into the maternal true pelvis.

Bloody Show

A pink or blood-streaked mucoid vaginal discharge that occurs as the cervix begins to soften, efface, and dilate, expelling the mucous plug.

First Stage of Labor

The stage of labor that begins with the onset of regular uterine contractions and ends with complete cervical effacement and dilation ($10\,\text{cm}$), divided into latent and active phases.

Second Stage of Labor

The stage of labor that begins with full dilation of the cervix ($10\,\text{cm}$) and ends with the birth of the infant.

Third Stage of Labor

The stage of labor that begins immediately after the birth of the fetus and concludes with the complete delivery and expulsion of the placenta.

Fourth Stage of Labor

The postpartum recovery period beginning immediately after the delivery of the placenta and continuing until the mother's physical and hemodynamic condition is stabilized.

Cardinal Movements of Labor

The positional adaptations and navigational movements the fetus makes to pass through the maternal birth canal: Engagement, Descent, Flexion, Internal rotation, Extension, Restitution & external rotation, and Expulsion.

Engagement

The cardinal movement that occurs when the widest transverse diameter of the fetal presenting part (the biparietal diameter) has passed through the pelvic inlet into the true pelvis (station $0$).

Expulsion

The final cardinal movement of the labor mechanism, in which the remainder of the infant's body emerges completely after the anterior and posterior shoulders are born.