Normal Labor and Delivery Processes

Flashcards covering the physiology of childbirth, maternal anatomy, obstetric terminology (G's & P's, TPAL, term definitions), factors affecting labor (the 5 Ps), and the four stages of labor and delivery.

Labor

The process by which the uterus expels the fetus, the placenta, and the amniotic sac.

Obstetrics

The branch of medicine and surgery concerned with childbirth and the care of women giving birth.

Normal physiologic labor and birth

A birth powered by the innate human capacity of the woman and fetus, characterized by spontaneous onset, vaginal birth, and physiological blood loss.

Placenta

The organ that facilitates oxygen and nutrient exchange between fetus and maternal circulation; it starts developing in the 3rd week of pregnancy and lasts roughly 41 weeks.

Antepartum

The time between conception and onset of labor, used interchangeably with the word prenatal.

Intrapartum

The timeframe from the onset of labor until the birth of the baby and placenta.

Postpartum

The period from birth until the woman's body returns to an essentially prepregnant condition, typically lasting about 6 weeks.

Gestation

The number of weeks since the first day of the last menstrual period ($LMP$) in a pregnancy.

Early term

Gestation extending from $37\,0/7$ weeks through $38\,6/7$ weeks.

Full term

Gestation extending from $39\,0/7$ weeks through $40\,6/7$ weeks.

Late term

Gestation extending from $41\,0/7$ weeks through $41\,6/7$ weeks.

Postterm

Gestation reaching $42\,0/7$ weeks and beyond.

N
Ngele's Rule

A rule to calculate the estimated date of birth ($EDB$): First day of last menstrual period, minus 3 months, plus 7 days.

Abortion

Birth that occurs before 20 weeks’ gestation or the birth of a fetus or newborn weighing less than $500\,g$; can be spontaneous (miscarriage) or induced.

Preterm labor

Labor that occurs after 20 weeks but before the completion of 37 weeks of gestation.

Postterm labor

Labor that occurs after 42 weeks of gestation.

Gravida

Any pregnancy, regardless of duration.

Para

A woman who has given birth after 20 weeks gestation, regardless of whether the baby was born dead or alive.

Nulligravida

A woman who has never been pregnant.

Primigravida

A woman who is pregnant for the first time.

TPAL

A system to convey obstetric history: Terms (births at $\geq 37$ weeks), Preterm (births between $20$ and $37$ weeks), Abortions (before $20$ weeks), and Living children.

Gynecoid Pelvis

A pelvic type with a rounded inlet and adequate diameters in the midpelvis and outlet; favorable for vaginal birth.

Android Pelvis

A heart-shaped pelvic inlet with reduced midpelvis diameters and outlet capacity; not favorable for vaginal birth.

Anthropoid Pelvis

An oval-shaped inlet with a long anteroposterior diameter; favorable for vaginal birth.

Platypelloid Pelvis

An oval-shaped inlet with long transverse diameters and inadequate outlet capacity; not favorable for vaginal birth.

Effacement

The thinning of the cervix, characterized by the drawing up of the internal os and cervical canal into the uterine side walls; reported as a percentage.

Dilation

The widening of the cervical os and canal from less than $1\,cm$ to $10\,cm$.

Fetal Lie

The relationship of the long axis (spine) of the fetus with the long axis of the mother; can be longitudinal or transverse.

Fetal Presentation

The body part of the fetus coming first into the pelvis and against the cervix; cephalic (head) is expected, while breech (butt) or shoulder is a malpresentation.

Fetal Attitude

The position of the fetal body in relation to the head in cephalic presentations; categories include vertex, military, brow, and face.

Vertex attitude

The fetal neck is completely flexed; the most common and desired attitude for birth.

Molding

The overlapping of fetal cranial bones under pressure of uterine contractions to facilitate passage through the pelvis.

Mentum

The landmark for the chin of the fetal skull.

Station

The relationship of the presenting part to an imaginary line between the ischial spines; measured from $-5\,cm$ to $+5\,cm$ where $0$ is at the spines.

Engagement

Occurs when the largest diameter ($BPD$) of the fetal presenting part reaches or passes the pelvic inlet.

Frequency of contractions

The time from the beginning of one uterine contraction to the beginning of the next, measured in minutes.

Duration of contractions

The time from the beginning to the end of a single uterine contraction.

Acme

The peak or most intense point of a uterine contraction.

Tachysystole

The occurrence of more than 5 uterine contractions in 10 minutes.

Resting Tone (uterine tonus)

The lowest intra-amniotic pressure between contractions; relaxation allows oxygen replenishment for the fetus.

Lightening

A sign of impending labor where the fetus begins to settle into the pelvis.

Bloody show

The loss of the mucus plug and small amount of blood occurring 24 to 48 hours before labor onset.

TACO

A mnemonic for assessing amniotic fluid upon Rupture of Membranes ($ROM$): Time, Amount, Color, Odor.

PROM

Premature Rupture of Membranes; spontaneous rupture before the onset of labor.

First Stage: Early/Latent Phase

Cervical dilation from $0$ to $3\,cm$; contractions are mild and regular; the woman is often excited and talkative.

First Stage: Active Phase

Cervical dilation from $4$ to $7\,cm$; contractions are more frequent and intense; fetal descent is progressive.

First Stage: Transition Phase

Cervical dilation from $8$ to $10\,cm$; contractions are very intense; maternal characteristics include restlessness and loss of control.

Second Stage of Labor

The stage from full cervical dilation ($10\,cm$) through the delivery of the baby; characterized by the maternal urge to push.

Third Stage of Labor

The time from birth of the baby until the delivery of the placenta; signs include fundus rise and a gush of blood.

Schultze mechanism

Placental separation from inside to outer margins; placenta is expelled with the fetal (shiny) side presenting; known as "Shiny Schultze."

Duncan mechanism

Placental separation from outer margins inward; placenta is expelled with the maternal (rough) side presenting; known as "Dirty Duncan."

Fourth Stage of Labor

The initial recovery period 1 to 4 hours after delivery; involves bonding, breastfeeding, and hemodynamic readjustment.