Obstetrics: Labour Onset and Fetal Positioning

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Questions and Answers

What are the hormonal changes that play a key role in initiating labour?

The increase in oxytocin and prostaglandins.

What factors influence fetal positioning in the uterus during labour?

Maternal posture and movement, uterine shape and size, fetal size and shape, and placental location.

What is the normal pattern of uterine contractions during labour?

Contractions every 5-30 minutes, lasting 30-70 seconds, and increasing in intensity as labour progresses.

What is the significance of 3-4 cm cervical dilation during labour?

Active labour begins. Signup and view all the answers

What is the average duration of the first stage of labour?

8-12 hours. Signup and view all the answers

What is the purpose of the combination of contractions and retraction during labour?

To move the fetus down the birth canal, dilate the cervix, and prepare the uterus for the second stage of labour. Signup and view all the answers

What is the term for the opening of the cervix during labour?

Cervical dilation. Signup and view all the answers

What is the division of the first stage of labour into two phases?

Early labour (0-3 cm dilation) and active labour (4-7 cm dilation). Signup and view all the answers

What is the definition of the first stage of labour, and what marks its beginning and end?

The first stage of labour begins with the onset of regular uterine contractions and ends when the cervix is fully dilated, usually at 10cm. Signup and view all the answers

What are the characteristics of true labour contractions, and how do they progress during labour?

True labour contractions are regular, rhythmic, and increase in intensity. They last around 30-70 seconds, with a frequency of 3-5 per 10 minutes, becoming more frequent and intense as labour progresses. Signup and view all the answers

What is retraction, and what is its purpose in labour?

Retraction is the process by which the uterine muscle shortens and thickens, pulling the cervix upwards and outwards. Its purpose is to help dilate the cervix and push the baby down the birth canal. Signup and view all the answers

How does retraction affect the cervix, and what is the outcome?

Retraction causes the cervix to thin and dilate, helping to move the cervix out of the way, allowing the baby to descend. Signup and view all the answers

What is the difference between Braxton Hicks contractions and true labour contractions?

Braxton Hicks contractions are irregular, mild, and practice contractions, whereas true labour contractions are regular, intense, and productive. Signup and view all the answers

What are the two phases of the first stage of labour, and what characterizes each phase?

The two phases are early labour (latent phase) and active labour. Early labour is characterized by contractions becoming more frequent and intense, with the cervix dilating to 3-4cm. Active labour is characterized by the cervix dilating from 4-10cm, with contractions becoming stronger and more frequent. Signup and view all the answers

Study Notes

Onset Of Labour

The onset of labour is a complex and not fully understood process
Hormonal changes, particularly the increase in oxytocin and prostaglandins, play a key role in initiating labour
Other factors contributing to the onset of labour include:
- Fetal movement and pressure on the cervix
- Stretching of the uterus and pelvic floor
- Changes in the cervix and lower uterine segment

Fetal Positioning

Fetal positioning refers to the way the baby is positioned in the uterus during labour
Optimal fetal positioning is important for a smooth and efficient labour
Factors influencing fetal positioning include:
- Maternal posture and movement
- Uterine shape and size
- Fetal size and shape
- Placental location

Contraction Patterns

Contraction patterns refer to the frequency, duration, and intensity of uterine contractions during labour
Normal contraction patterns include:
- Contractions every 5-30 minutes, lasting 30-70 seconds, and increasing in intensity
- Contractions becoming more frequent, longer, and stronger as labour progresses
Abnormal contraction patterns include:
- Contractions that are too frequent, too long, or too strong
- Contractions that are irregular or unpredictable

Cervical Dilation

Cervical dilation refers to the opening of the cervix during labour
The cervix dilates from 0-10 cm, with 10 cm being fully dilated
Cervical dilation is typically measured in centimeters, with the following milestones:
- 3-4 cm: active labour begins
- 7-8 cm: transition phase begins
- 10 cm: full dilation, ready for pushing

Event 1st Stage of Labour

The first stage of labour is the longest stage, lasting from the onset of labour to full cervical dilation
The first stage of labour is divided into two phases:
- Early labour (0-3 cm dilation): contractions are mild and irregular
- Active labour (4-7 cm dilation): contractions are stronger and more frequent
The first stage of labour can last anywhere from 6-24 hours, with an average duration of 8-12 hours

Contraction and Retraction

Contractions refer to the periodic tightening of the uterine muscle during labour
Retraction refers to the process of the uterine muscle shortening and thickening during contractions
The combination of contractions and retraction helps to:
- Move the fetus down the birth canal
- Dilate the cervix
- Prepare the uterus for the second stage of labour (pushing)

Onset of Labour

Hormonal changes, including increased oxytocin and prostaglandins, initiate labour
Fetal movement and pressure on the cervix contribute to the onset of labour
Stretching of the uterus and pelvic floor, and changes in the cervix and lower uterine segment, also play a role

Fetal Positioning

Fetal positioning is crucial for a smooth and efficient labour
Maternal posture and movement, uterine shape and size, fetal size and shape, and placental location influence fetal positioning

Contraction Patterns

Normal contractions occur every 5-30 minutes, last 30-70 seconds, and increase in intensity as labour progresses
Abnormal contraction patterns include contractions that are too frequent, too long, or too strong, or irregular and unpredictable

Cervical Dilation

Cervical dilation measures the opening of the cervix, from 0-10 cm
3-4 cm dilation marks the beginning of active labour
7-8 cm dilation marks the transition phase
10 cm dilation indicates full dilation, ready for pushing

First Stage of Labour

The first stage of labour lasts from the onset of labour to full cervical dilation
Early labour (0-3 cm dilation) has mild and irregular contractions
Active labour (4-7 cm dilation) has stronger and more frequent contractions
The first stage of labour typically lasts 8-12 hours, but can range from 6-24 hours

Contraction and Retraction

Contractions are periodic tightenings of the uterine muscle during labour
Retraction is the shortening and thickening of the uterine muscle during contractions
Contractions and retraction help move the fetus down the birth canal, dilate the cervix, and prepare the uterus for the second stage of labour (pushing)

Event of 1st Stage of Labour

Begins with onset of regular uterine contractions and ends when cervix is fully dilated (usually 10cm)
Divided into two phases: Early labour (latent phase) and Active labour (active phase)

Phases of 1st Stage of Labour

Early Labour (Latent Phase)
- Contractions become more frequent and intense
- Cervix dilates to 3-4cm
Active Labour (Active Phase)
- Cervix dilates from 4-10cm
- Contractions become stronger and more frequent

Contractions

Characteristics
- Regular, rhythmic, and increasing in intensity
- Lasting around 30-70 seconds, with a frequency of 3-5 per 10 minutes
- Becoming more frequent and intense as labour progresses
Types of Contractions
- Braxton Hicks Contractions
  - Irregular, mild, and practice contractions
  - Prepare the uterus for labour
- True Labour Contractions
  - Regular, intense, and productive contractions
  - Help dilate the cervix

Retraction

Definition
- Process by which the uterine muscle shortens and thickens
- Pulls the cervix upwards and outwards
Purpose
- Helps dilate the cervix and push the baby down the birth canal
Effects on the Cervix
- Causes the cervix to thin and dilate
- Helps move the cervix out of the way, allowing the baby to descend
Relationship with Contractions
- Occurs in response to contractions
- Helps progress labour

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Description

Understand the complex process of labour onset, including hormonal changes and other factors, as well as fetal positioning in the uterus. Learn about the key role of oxytocin, prostaglandins, and fetal movement in initiating labour.