The Stages of Labour

Labour is divided into three stages

First Stage: This stage lasts from the onset of labour( When the woman begins to have regular painful uterine contractions) and a dilated cervix of 2-3 cm to a full cervical dilation of 10 cm.

The average duration of the first stage is about 12 to 14 hours for primigravida (woman who have not delivered before, ie first time delivery) . For women who have delivered before  (Multipara) this stage lasts about 8 to 10 hours.

 

Second Stage: The second stage starts at the time of full cervical dilatation and ends with the birth of the baby. The average duration of the second stage for a primigravida is about 25 minutes while for a multipara it lasts for about 15 minutes.

 

Third Stage: The third stage lasts from the time the baby is born to the time the placenta is delivered. The average duration of the third stage is about 5 minutes for the primigravida and 6 minutes for the multipara.

What is the average duration of labour?

In primigravida (woman who have not delivered before, ie first time delivery) the average total duration of labour is about 14 hours. While for a multipara (Women who have delivered before) the average total duration of labour is about 10 hours.

 

The components or essential factors of labour

 

The components or essential factors of labour are commonly referred to as the three P’s of  labour. These include:

 

i) The Passage: There are four types of pelvis, the gynecoid, android, anthropoid and platypelloid. The gynecoid pelvis is the normal female pelvis while the male type is referred to as the android. The pelvic inlet, the mid-cavity and the outlet should be carefully evaluated.

 

If the clinical pelvimetry is in doubt a lateral x-ray pelvimetry is very useful in assaying the bony pelvis. The soft tissue of the pelvis which includes the muscles, fascia and ligaments should also be assayed as excessive scarring can delay labour.

 

ii) The Powers: As labour progresses in normal labour the contractions become regular , stronger and well co-ordinated . They occur every 2 to 3 minutes (about 3 times per 10 minutes) . The intensity (force of contractions increases) from an average of 20 to 30 mmHg to 50 mmHg.

As the labour progresses the upper segment becomes thicker while the lower segment becomes thinner.

 

iii) The Passenger: The passenger refers to the baby. The average size babies tend to have the best prognosis (assuming that the baby does not have any congenital malformations/diseases) in terms of neonatal well being . 

The average size of the fetus at term(Birth weight) varies from country to country .eg in Sri Lanka the average birth weight is 2.8 Kg while in Nigeria it is 3.4 Kg.

 

References:

Dewhurst’s Textbook of Obstetrics and Gynaecology for Postgraduates (Sixth Edition)-Edited by Keith Edmonds FRCOG , FRACOG

Oxford Handbook of Clinical Specialties-6 th edition

Obstetrics by Ten Teachers- edited by Stuart Campbell and Ash Monga- 17th edition

Textbook of Obstetrics and Gynaecology for Medical Students by Akin Agboola et al-2nd edition

 

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