First Stage of Labor: Physiology & Monitoring with Partograph
Table of Contents
1. Introduction #
Labor is the physiological process that results in the birth of a baby and expulsion of the placenta. Understanding the first stage of labor is crucial for effective nursing care during childbirth. This stage is typically the longest and involves significant physiological changes in both the mother and fetus.
The first stage of labor begins with the onset of regular uterine contractions and ends with complete cervical dilation. Proper monitoring during this stage using tools like the partograph can significantly reduce complications related to prolonged labor, including postpartum hemorrhage, infection, and obstructed labor.
Focus Word: First Stage of Labor
The first stage of labor is the period from the beginning of regular contractions until complete cervical dilation (10 cm), typically accounting for the majority of the labor process.
Among the five major causes of maternal mortality (hypertension, hemorrhage, infection, obstructed labor, and unsafe abortion), three—hemorrhage, infection, and obstructed labor—are directly correlated with prolonged labor.
2. Physiology of Normal Labor #
Human labor is physiologically complex compared to other mammals due to our upright posture and larger fetal head size. The process has evolved over millions of years, with adaptations like rotation of the fetal head during passage through the birth canal making successful birth possible.
2.1 Triggers of Labor #
During pregnancy, the uterus is prevented from regular contractions primarily by progesterone from the placenta. As the pregnancy approaches term, several changes occur that initiate labor:
- Hormonal Shifts: Changes in the ratio of estrogen to progesterone
- Fetal Contributions: Secretion of steroids from the fetal adrenal glands
- Mechanical Factors: Increased tension in the uterine wall as the fetus grows
- Prostaglandins: Release from membranes and uterine decidua, especially after membrane rupture
Memory Aid: PERF Triggers
Remember the triggers of labor with the acronym PERF:
- Prostaglandins increase
- Estrogen dominance over progesterone
- Relaxin peaks
- Fetal cortisol rises
2.2 Uterine Contractions #
Uterine contractions are the driving force behind labor. These involuntary contractions of the myometrium are characterized by:
- Gap Junction Formation: Development of low electrical resistance contacts between myometrial cells, allowing synchronized contractions
- Triple Gradient Effect: Contractions that begin at the fundus, are strongest at the fundus, and spread downward
- Increment in Strength: Progressive increase from approximately 20 mm Hg at labor onset to 50-80 mm Hg in active labor
- Retraction: Unique ability of the uterus to maintain some contraction even during relaxation phases, progressively moving the fetus downward
2.3 Cervical Changes #
The cervix undergoes two significant changes during labor:
- Effacement: The thinning and shortening of the cervix
- Dilation: The opening of the cervical os
These changes are facilitated by:
- Softening of cervical tissue through increased water content and collagen reorganization
- Pressure from the presenting part (usually the fetal head) and amniotic fluid
- Hormonal influence, particularly prostaglandins
Physiological Insight
Unlike most smooth muscle, uterine muscle can maintain partial contraction even while relaxing. This phenomenon, known as retraction, allows the uterus to gradually push the fetus downward throughout labor.
3. First Stage of Labor #
The first stage of labor is the interval between the onset of regular uterine contractions and complete cervical dilation (10 cm). It typically lasts 8-12 hours in nulliparous women and 3-8 hours in multiparous women, representing the longest stage of labor.
First Stage of Labor: Showing cervical dilation, uterine contractions, and fetal position
The first stage of labor is divided into three phases:
3.1 Latent Phase #
The latent phase represents the early part of the first stage of labor:
- Cervical Dilation: From 0 to 3-4 cm
- Contractions: Mild to moderate, irregular (every 5-20 minutes), lasting 30-45 seconds
- Duration: Up to 8 hours in nulliparous women, typically shorter in multiparous women
- Maternal Behavior: Woman is usually comfortable, able to talk through contractions
3.2 Active Phase #
The active phase represents the middle part of the first stage:
- Cervical Dilation: From 4 to 8 cm
- Contractions: Moderate to strong, regular (every 2-5 minutes), lasting 45-60 seconds
- Rate of Dilation: Approximately 1 cm/hour in nulliparous women, faster (~1.6 cm/hour) in multiparous women
- Maternal Behavior: Woman becomes more focused on labor, may need pain management
Memory Aid: The 1-1-1 Rule of Active Labor
Remember the rate of normal progress in active labor with the 1-1-1 Rule:
- Cervix dilates at 1 cm per hour
- Contractions occur every 1-2 minutes
- Each contraction lasts about 1 minute
3.3 Transition Phase #
The transition phase is the final part of the first stage:
- Cervical Dilation: From 8 to 10 cm (complete)
- Contractions: Strong, frequent (every 2-3 minutes), lasting 60-90 seconds
- Duration: Typically the shortest phase, lasting 15-60 minutes
- Maternal Behavior: Woman often experiences intense discomfort, may feel pressure in rectum, urge to push, nausea/vomiting
| Parameter | Latent Phase | Active Phase | Transition Phase |
|---|---|---|---|
| Cervical Dilation | 0-3/4 cm | 4-8 cm | 8-10 cm |
| Contraction Frequency | Every 5-20 min | Every 2-5 min | Every 2-3 min |
| Contraction Duration | 30-45 seconds | 45-60 seconds | 60-90 seconds |
| Pain Intensity | Mild to moderate | Moderate to severe | Severe |
| Typical Duration | Up to 8 hours | 3-5 hours | 15-60 minutes |
4. Monitoring with Partograph #
The partograph (or partogram) is a graphical representation of the progress of labor and maternal and fetal condition during labor. It serves as an early warning system for identifying abnormal labor progress and potential complications.
Partograph Definition
The partograph is a graphical presentation of the progress of labor, and of fetal and maternal condition during labor. It is the best tool to help detect whether labor is progressing normally or abnormally, and to warn of signs of fetal distress or maternal complications.
4.1 Components of a Partograph #
The standard partograph includes:
-
Patient Identification Section
- Name, age, gravida/para status, hospital number
- Date and time of admission
- Time of membrane rupture
-
Fetal Condition
- Fetal heart rate (recorded every 30 minutes)
- Amniotic fluid color (recorded every 4 hours)
- Moulding of the fetal skull (recorded every 4 hours)
-
Labor Progress
- Cervical dilation (plotted with ‘X’, recorded every 4 hours)
- Descent of fetal head (plotted with ‘O’, recorded every 4 hours)
- Alert and action lines
-
Uterine Activity
- Frequency and duration of contractions (recorded every 30 minutes)
-
Maternal Condition
- Vital signs: Blood pressure (every 4 hours), pulse (every 30 minutes), temperature (every 2 hours)
- Urine output, protein, and acetone (whenever urine is passed)
- Medications and IV fluids administered
Memory Aid: 4-3-2-1 Partograph Timing
Remember the frequency of observations with the 4-3-2-1 rule:
- 4 hours: Cervical dilation, fetal descent, amniotic fluid, moulding, blood pressure
- 30 minutes: Fetal heart rate, contractions, maternal pulse
- 2 hours: Temperature
- 1 time: Urine (check each time passed)
4.2 Interpretation #
Proper interpretation of the partograph involves monitoring several key indicators:
A. Cervical Dilation
- Normal: At least 1 cm/hour in active phase
- Record with ‘X’ symbol on the partograph
- Start plotting on the partograph at 4 cm dilation (beginning of active phase)
B. Fetal Head Descent
- Assessed by vaginal examination relative to ischial spines
- Record with ‘O’ symbol on the partograph
- Station 0 (head at ischial spines) corresponds to 3 on the partograph
- Should progress along with cervical dilation
C. Uterine Contractions
- Frequency: Number per 10 minutes
- Duration: Less than 20 seconds (weak), 20-40 seconds (moderate), more than 40 seconds (strong)
- Shading indicates intensity: Light (mild), medium (moderate), dark (strong)
D. Fetal Condition
- Normal FHR: 120-160 beats/minute
- Amniotic fluid: Clear (C), blood-stained (B), meconium (M1-light, M2-moderate, M3-thick)
- Moulding: 0 (separated sutures) to +3 (severely overlapped, not reducible)
| Station of Fetal Head | Corresponding Mark on Partograph | Description |
|---|---|---|
| -3 or -4 | 5 | Head floating, not engaged |
| -1 or -2 | 4 | Head descending, approaching ischial spines |
| 0 | 3 | Head at level of ischial spines |
| +1 | 2 | Head below ischial spines |
| +2 | 1 | Head visible at vaginal opening during contractions |
| +3 | 0 | Crowning (head visible between contractions) |
4.3 Alert and Action Lines #
The partograph contains two diagonal lines that help in decision-making:
- Alert Line: Represents cervical dilation of 1 cm/hour, starting at 4 cm. When cervical dilation falls to the right of this line, it indicates slower-than-expected progress.
- Action Line: Drawn 4 hours to the right of the Alert Line. When cervical dilation falls on or beyond this line, it indicates significantly prolonged labor requiring intervention.
Clinical Alert!
If the cervical dilation plot crosses the Alert Line, refer the patient to a higher-level facility. This indicates abnormally slow labor progress that may lead to complications if not properly managed.
Indications for Immediate Referral
- Cervical dilation plot crosses the Alert Line
- Fetal heart rate below 120 or above 160 beats/minute for more than 10 minutes
- Thick meconium-stained amniotic fluid (M3) at any stage
- Moderate meconium staining (M2) in early active phase
- Moulding of +3 with poor progress of labor
- Maternal vital signs outside normal ranges
5. Best Practices & Updates #
Recent developments in labor monitoring and management include:
3 Best Practices in First Stage Labor Management
-
WHO Labor Care Guide (LCG)
The WHO has updated the traditional partograph with the Labor Care Guide, which reflects current evidence on normal labor progression. The LCG acknowledges that labor can progress more slowly than 1 cm/hour without adverse outcomes and promotes more individualized care.
-
Intermittent Auscultation
For low-risk pregnancies, intermittent auscultation (every 15-30 minutes in first stage, every 5 minutes in second stage) is recommended over continuous electronic fetal monitoring, which can increase cesarean rates without improving outcomes.
-
Freedom of Movement and Position
Evidence supports allowing women to adopt various positions and move freely during the first stage of labor. Upright positions can reduce labor duration, decrease pain perception, and lower rates of interventions.
Recent Updates in Labor Management
- Revised Definition of Labor Phases: Research has shown that the transition from latent to active phase may occur later than previously thought, closer to 6 cm dilation in many women.
- Recognition of Labor Pattern Variations: Greater acceptance of individual variations in labor progress, especially in the latent phase.
- Delayed Intervention Approach: More conservative management of slow progress in the absence of other complications, with intervention recommended after 4 hours of stalled labor in active phase.
Memory Aid: SLOWER Progress is Sometimes OK
Remember when to be concerned about slower-than-expected labor with the acronym SLOWER:
- Stalled for >4 hours in active phase
- Line (alert) crossed on partograph
- Ominous signs in mother (fever, tachycardia)
- Worrying fetal heart patterns
- Excessive moulding (+3)
- Rupture of membranes >18 hours
6. Summary #
Key Points
- The first stage of labor is the interval between onset of regular uterine contractions and complete cervical dilation (10 cm), typically lasting 8-12 hours in nulliparous women and 3-8 hours in multiparous women.
- Physiologically, labor involves complex hormonal changes, uterine contractions facilitated by gap junction formation, and cervical effacement and dilation.
- The first stage consists of three phases: latent (0-4 cm), active (4-8 cm), and transition (8-10 cm), each with characteristic patterns of contractions and maternal behaviors.
- The partograph is an essential tool for monitoring labor progress, with components tracking fetal condition, maternal condition, and labor progression.
- Alert and Action lines on the partograph help identify abnormal labor patterns early, allowing for timely intervention or referral.
- Recent updates in labor management recognize greater variation in normal labor patterns and promote more individualized care approaches.
Clinical Application
As a nurse monitoring the first stage of labor, your primary goals are to:
- Accurately assess and document cervical changes, fetal descent, and contraction patterns
- Monitor fetal and maternal wellbeing throughout labor
- Recognize deviations from normal patterns that require intervention
- Provide appropriate supportive care to enhance the physiological process of labor
- Use the partograph as an early warning system to prevent complications related to prolonged labor