Normal and Abnormal Labor

Labor is the normal physiologic process defined as uterine contractions resulting in dilatation and effacement of the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Posterior Abdominal Wall, which culminates in expulsion of the fetus and the products of conception. Labor has 3 stages: the 1st stage starts with the onset of regular contractions, the 2nd stage starts with full cervical dilation, and the 3rd stage starts immediately after fetal delivery and ends with delivery of the placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity. The primary factors required for labor to progress normally are the three Ps: power (uterine contractions), passenger (the fetus), and passage (the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis). Labor may become abnormally protracted and require augmentation, usually with oxytocin, to prevent maternal and fetal complications.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Table of Contents

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Overview

Definition: Normal labor

Labor is defined as regular uterine contractions that cause cervical dilation and effacement, leading to delivery of the fetus and the products of conception.

  • Gestational age: occurs at 37–42 weeks of gestational age (full-term)
  • Onset: spontaneous (as opposed to induced)
  • Progression: spontaneous, without complications 

There are subtle differences in normal labor between primiparous and multiparous women (reviewed below).

  • Primiparous: a woman’s 1st delivery
  • Multiparous: a woman with prior deliveries

Monitoring progress of labor

Labor progress is followed by serial cervical exams to assess dilation, effacement, and fetal station.

  • Cervical dilation: 
    • A measurement of the diameter of the cervical canal
    • Reported in centimeters
    • Full dilation: 10 cm
  • Cervical effacement:
    • An estimate of cervical thinning
    • Cervix starts at > 2 cm → effaces to paper thin (full effacement)
    • Reported as a percentage of progress
    • Full effacement: 100% effaced 
  • Fetal station:
    • How high (or low) the presenting fetal part is compared to the maternal ischial spine
    • Reported in centimeters:
      • Positive numbers are closer to the vaginal introitus
      • Negative numbers are higher in the pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis
    • Fetal head at the introitus: +3–5 cm

Stages of labor

There are 3 stages of labor:

  1. The 1st stage: 
    • Begins with the onset of regular uterine contractions that cause cervical change
    • Ends with full cervical dilation (10 cm)
  2. The 2nd stage: 
    • Begins when the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Posterior Abdominal Wall reaches full dilation (10 cm)
    • Ends with delivery of the fetus
  3. The 3rd stage: 
    • Begins immediately after delivery of the fetus 
    • Ends with delivery of the placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity
Progression through the 3 stages of labor

Progression through the 3 stages of labor

Image by Lecturio.

Related videos

The 3 Ps: Power, Passenger, and Passage

For labor to progress normally, there needs to be adequate power from uterine contractions, the fetus needs to tolerate the contractions, and the fetus needs to fit through the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis. These requirements are referred to as the 3 Ps: Power, Passenger, and Passage.

Power: Uterine contractions

  • Contractions must be powerful enough to dilate the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Posterior Abdominal Wall and expel the fetus
  • Can be measured by:
    • External pressure transducer (tocometry): measures frequency and strength of contractions relative to each other
    • Internal uterine pressure catheter (IUPC): measures frequency and numerical strength of contractions in Montevideo units (MVUs)
  • Montevideo units: the strength of all contractions measured within a 10-minute period:
    • “Adequate power” to effect delivery: 200 MVUs in 10 minutes
    • “Inadequate power” is a cause of abnormal labor progress.

Passenger: Fetus

The fetal head must ultimately be flexed and directly aligned with the maternal spine in order to fit through the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis.

  • Presentation: based on the “presenting part” of the fetus at the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Posterior Abdominal Wall:
    • Vertex: head down
    • Breech: 
      • Frank breech: bottom down, legs extended
      • Complete breech: bottom down, legs flexed
      • Footling breech: feet down
    • Face: 
      • Mentum anterior (MA): chin is anterior, face can flex → compatible with vaginal delivery
      • Mentum posterior (PA): chin is posterior, face cannot flex, incompatible with vaginal delivery
      • Remember: “MA can, PA can’t” for vaginal deliveries
    • Brow: forehead down, large diameter, incompatible with vaginal delivery
  • Positions: direction of the fetal head in relation to the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis in vertex presentations
    • Occiput anterior (OA): fetus is facing maternal spine; easiest for delivery
    • Occiput posterior (OP): fetus is facing maternal bladder; more challenging
    • Occiput transverse (OT): fetal head is sideways (facing a maternal hip)
      • Fetus typically enters the pelvic inlet in an OT position before undergoing internal rotation.
      • The fetal head will not fit under the pubic bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones in this position.
  • Fetal tolerance of labor: infant must tolerate uterine contractions
  • Normal size infant: infant must fit through maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis
  • Number of infants: 
    • Singletons and twins are candidates for a trial of labor
    • Surviving triplets and higher-order multiples should be delivered via cesarean 
Diameters of the fetal head

Diameters of the fetal head

Image by Lecturio. License: CC BY-NC-SA 4.0

Passage: Pelvis

The maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis must be large enough to accommodate the fetus. The pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis is assessed as “adequate” or “inadequate” for a trial of labor on the initial exam.

  • Pelvis shapes:
    • Gynecoid: allows the fetal head to rotate to OA
    • Anthropoid: causes the head to rotate to OP
    • Platypelloid: causes the head to stay OT
    • Android: fetal head has difficulty engaging
  • Clinical relevance of pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis shape:
    • Difficult to determine on exam
    • No shape is a contraindication for a trial of labor.
    • Gynecoid is the easiest for vaginal delivery
    • Android and platypelloid are the most difficult for vaginal delivery

The 1st Stage of Labor

Definitons

  • Starts with the onset of regular contractions that result in:
    • Cervical change (dilation and effacement)
    • Descent of the fetus
  • Ends with full cervical dilation 
    • Full cervical dilation: 10 cm dilated
    • Full effacement: 100% thinned out (this may occur before the 1st stage ends)
Table: Length of the 1st stage of labor
Primiparous Multiparous
Latent labor Lasts < 20 hours Lasts < 14 hours
Active labor 1.2 cm/hour 1.5 cm/hour
Latent phase: onset of contractions until 4–6 cm cervical dilation
Active phase: onset of contractions until 6–10 cm cervical dilation
Cervical changes during the 1st stage of labor

Cervical changes during the first stage of labor

Image: “2920 Stages of Childbirth-02” by OpenStax College. License: CC BY 4.0, cropped by Lecturio.
Divisions and timing of the first stage of labor

Divisions and timing of the 1st stage of labor:
Accel.: acceleration
Decel.: deceleration
Max: maximum

Image by Lecturio.

Latent phase

In the late 3rd trimester, irregular contractions and runs of nonpersistent regular contractions are common. The latent phase is the establishment of true labor, with regular persistent contractions that will continue through delivery.

  • Dilation: 0 to 4–6 cm 
  • Effacement: variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables
    • Primiparous: cervical effacement usually occurs before dilation
    • Multiparous: dilation usually precedes significant effacement 
  • Station: high (< 0)
  • Contractions: 
    • Frequency: regular, ≥ 3 per 10 minutes
    • Intensity: mild to moderate
    • Anesthesia Anesthesia Anesthesiology is the field of medicine that focuses on interventions that bring a state of anesthesia upon an individual. General anesthesia is characterized by a reversible loss of consciousness along with analgesia, amnesia, and muscle relaxation. Anesthesiology: History and Basic Concepts is generally not required.
  • Duration: 
    • Primiparous: < 20 hours
    • Multiparous: < 14 hours

Active phase

The active phase is a time of more rapid cervical change leading up to delivery.

  • Dilation: 6–10 cm 
    • Primiparous: 1.2 cm/hour
    • Multiparous: 1.5 cm/hour
  • Effacement: continues to 100%
  • Station: progressive descent to at least the ischial spines (0 station)
  • Contractions: 
    • Frequency: regular, ≥ 3 per 10 minutes
    • Intensity: strong
    • Anesthesia Anesthesia Anesthesiology is the field of medicine that focuses on interventions that bring a state of anesthesia upon an individual. General anesthesia is characterized by a reversible loss of consciousness along with analgesia, amnesia, and muscle relaxation. Anesthesiology: History and Basic Concepts is often requested.

Labor management

General management:

  • Continuous care and emotional support to the mother
  • Ambulation in low-risk women 
  • Adequate hydration

Maternal assessment:

  • Labor progression with serial cervical exams
  • Contraction adequacy
  • Vital signs
  • Urine output

Fetal assessment:

  • Intermittent auscultation of the fetal heart rate (lowest-risk women only)
  • Continuous cardiotocography (majority of women)
    • Includes women with any medical pain management Pain Management Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Pain is a subjective experience. Acute pain lasts < 3 months and typically has a specific, identifiable cause. Pain Management
    • Includes most women with any medical or obstetric complications

Abnormalities in the 1st stage of labor

Table: Diagnosis and Management of abnormalities in the 1st stage of labor
Phase Diagnosis Management
Protracted latent phase Abnormally long duration of the latent phase:
  • Primiparous: > 20 hours
  • Multiparous: > 14 hours
Options include:
  • Hydration
  • Rest with analgesia
  • Ambulation
  • Oxytocin
  • Consider amniotomy
Protracted active phase
  • Cervix is ≥ 6 cm and
  • Dilating < 1 cm over 2 hours
  • Oxytocin
  • Amniotomy (if membranes are not already ruptured)
Active phase arrest Cervix is ≥ 6 cm and:
  • No cervical change for ≥ 4 hours despite adequate contractions
    or
  • No cervical change for ≥ 6 hours regardless of contraction adequacy
Delivery by cesarean section
Table: Etiologies and management of abnormalities in the first stage of labor
Etiology Management
Power Inadequate power: < 200 MVUs measured with an IUPC Pitocin: to ↑ contraction strength

Passenger
Abnormal presentation:
  • Breech
  • Face
  • Brow
  • Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery recommended for:
    • Breech
    • Brow
    • Face: mentum posterior
  • Observation:
    • Face: mentum anterior
Abnormal position:
  • Occiput posterior
  • Occiput transverse
  • Observation
  • Attempt manual rotation
Fetal intolerance to labor / fetal heart rate abnormalities Fetal resuscitation:
  • Reposition the mother
  • Maternal oxygen
  • Maternal IV fluid bolus
  • ↓ pitocin
  • Amnioinfusion: an intrauterine fluid bolus delivered through an IUPC catheter
Higher order multifetal gestations Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery
Pelvis Cephalopelvic disproportion: fetal head does not fit through the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery
MVU: Montevideo unit
IUPC: Internal uterine pressure catheter

The 2nd Stage of Labor

The 2nd stage of labor begins with complete dilatation of the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Posterior Abdominal Wall and ends with delivery of the infant.

The cardinal movements of labor

The cardinal movements of labor describe the movements a fetus goes through as it moves through the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis. These movements begin in the 1st stage and are completed in the 2nd stage.

  • Engagement: occurs in the 1st stage 
    • Passage of the fetal head into the pelvic inlet
    • Fetal head is in an OT position: looking sideways, with the fetal head aligned with the fetal spine
  • Descent: downward passage of the fetal head through the pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis
  • Flexion: 
    • Passive flexion of the fetal head (fetal chin touches the fetal chest) as the head is pushed against maternal bony structures
    • Allows the narrowest diameter of the head to present
  • Internal rotation: 
    • Rotation of the fetal head to an anteroposterior direction
    • This rotation turns the fetal head relative to its own spine. 
      • Example: The fetal head is now looking down, while the fetal body is still mostly facing to the side.
      • This prepares the fetal head to move under the pubic bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones in the next step
  • Extension: fetal head extends (chin lifts off the chest) as it moves under the pubic bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones and appears through the vaginal opening
  • External rotation/restitution: 
    • Head rotates back to transverse to align with with the fetal spine again.
    • Allows delivery of the shoulders beneath the pubic bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones
  • Expulsion: 
    • Delivery of the rest of the fetal body, which has a smaller diameter than the fetal head and shoulders
    • Usually rapid
The cardinal movements of labor

The cardinal movements of labor

Image by Lecturio.

Normal parameters

  • Evaluated with the descent of the fetal head (station).
  • Normal duration of the 2nd stage depends on:
    • Primiparous versus multiparous
    • Epidural versus no epidural
Table: Normal parameters for the 2nd stage of labor
Primiparous Multiparous
With an epidural 3 hours 2 hours
Without an epidural 2 hours 1 hour

Management

  • Continue to monitor mother and infant as in the 1st stage of labor, but more frequently for:
    • Vital signs
    • Urine output
    • Pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain control
    • Fetal heart rate (FHR) and uterine contractions:
      • Cardiotocography (FHR tracing), or
      • Intermittent auscultation with palpation of contractions
  • Discourage lying flat → woman should have a hip roll under 1 side to keep the baby off the inferior vena cava Inferior vena cava The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs. Mediastinum and Great Vessels
  • Push/bear down with each contraction
Table: Abnormalities and management in 2nd stage of labor
Abnormality Definition Management
Protracted 2nd stage Duration is outside normal parameters
  • Observation: considered if fetal and maternal status are reassuring
  • Operative vaginal delivery if < +2 station
  • Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery if > +2 station
Arrested 2nd stage No descent for ≥ 2 hours Cesarean section
Shoulder dystocia Fetal head delivers, but shoulder remains lodged under the pubic bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones → obstetric emergency: fetus not getting oxygen during this time
  • Flex maternal legs
  • Suprapubic pressure: attempting to dislodge the anterior fetal shoulder
  • Delivery of the posterior arm Arm The arm, or "upper arm" in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm
  • Rotational maneuvers: attempt to rotate the fetal shoulder to allow delivery
  • Additional advanced maneuvers of last resort

The 3rd Stage of Labor

The 3rd stage of labor starts immediately after delivery of the baby and ends with complete expulsion of the placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity.

Clinical presentation

Signs that the placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity is ready to deliver include:

  • Lengthening of the umbilical cord
  • Gush of blood
  • Uterus becomes hard and globular

Management

  • Active management:
    • Gentle downward traction on the umbilical cord with countertraction on the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Posterior Abdominal Wall (to avoid uterine inversion)
    • IM or IV injection of oxytocin
  • Passive management:
    • Observation until spontaneous placental delivery occurs
    • Associated with higher rates of postpartum hemorrhage Postpartum hemorrhage Postpartum hemorrhage is one of the most common and deadly obstetric complications. Since 2017, postpartum hemorrhage has been defined as blood loss greater than 1,000 mL for both cesarean and vaginal deliveries, or excessive blood loss with signs of hemodynamic instability. Postpartum Hemorrhage
  • Normal parameters:
    • < 30 minutes
    • Typically takes 5–10 minutes 

Prolonged 3rd stage of labor

  • Diagnosis: 3rd stage > 30 minutes
  • Etiology: 
    • Abnormal placentation (e.g., placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity accreta)
    • Separated but trapped placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity due to rapid contraction of the lower uterine segment
  • Management:
    • Manual uterine exploration
    • Uterine relaxants (if lower uterine segment is preventing expulsion)
    • Surgical exploration
Human placenta shown a few minutes after birth

Human placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity shown a few minutes after birth:
The side shown faces the baby with the umbilical cord top right. The unseen side connects to the uterine wall.

Image: “Human placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity baby side” by Habj. License: Public Domain

Clinical Relevance

  • False labor (also known as Braxton-Hicks contractions): irregular uterine contractions or runs of regular contractions without cervical changes. These contractions do not increase in intensity or duration, and they are common and normal in the 3rd trimester. Women should be reassured and counseled about hydration, as dehydration Dehydration Volume status is a balance between water and solutes, the majority of which is Na. Volume depletion refers to a loss of both water and Na, whereas dehydration refers only to a loss of water. Dehydration is primarily caused by decreased water intake and presents with increased thirst and can progress to altered mental status and low blood pressure if severe. Volume Depletion and Dehydration was found to be associated with false labor.
  • Prelabor rupture of membrane: the rupture of membranes (chorion and amnion) before the onset of labor. Women usually present with a “gush of amniotic fluid” from the vagina Vagina The vagina is the female genital canal, extending from the vulva externally to the cervix uteri internally. The structures have sexual, reproductive, and urinary functions and a rich blood supply, mainly arising from the internal iliac artery. Vagina, Vulva, and Pelvic Floor followed by a continuous dribble. Infections frequently develop after the membranes have been ruptured for a prolonged period (> 18 hours). Sterile speculum examination is done to visualize the presence of amniotic fluid pooling within the posterior vaginal fornix. Prelabor rupture of membrane may precipitate labor, but it is not considered to be labor in and of itself.

References

  1. Ehsanipoor, R.M., Satin, A. (2020). Normal and abnormal labor progression. UpToDate. Retrieved March 18, 2021, from https://www.uptodate.com/contents/normal-and-abnormal-labor-progression
  2.  American College of Obstetric and Gynecology Committee on Obstetrics (2019). Approaches to limit intervention during labor and birth. Committee opinion 766. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2019/02/approaches-to-limit-intervention-during-labor-and-birth 

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