Normal Labour or eutocia is a physiologic process during which the products of conception (ie, the fetus, membranes, umbilical cord, and placenta) are expelled from the uterus. Labour is said to be normal only when the fetus is mature and the process is spontaneous and uncomplicated.
Abnormal labor or complicated labor is known as dystocia .
Although the terms 'labor' and 'delivery' are used as synonyms, they really describe two different processes. Labor is the process by which a baby is delivered. Delivery is the actual birth of the baby and does not include the labor pains, uterine contractions etc. which make up a the process of labor.
The normal duration of active labor is 8-10 hours in the first pregnancy and 6-8 hours in later pregnancies.
The first labor in a woman is usually more difficult than subsequent labors.
Age of the pregnant woman is also a determinant in the type of labor. Labor is easiest when the woman is between 18-25 years of age. Risk of maternal injuries is highest in a woman in her first labor when she is below 18 years or above 35 years.
Risk of maternal injuries also increases in woman who is in labor for the 5th time or higher.
Many women start to get uterine pains in the later stage of pregnancy. These are false labor pains and need to be differentiated form true labor pains.
|True Labor Pains||False Labor Pains|
|Increases progressively in frequency, duration and intensity||Does not do so|
|Pain in abdomen radiates to back||Pain is mainly in the abdomen|
|Progressive dilation and effacement of cervix||No effect on cervix|
|Cannot be relieved by painkillers or sedatives||Can be relieved by painkillers or sedatives|
Why Labor Starts
The exact cause of onset of labor is not known. There are different theories:
- Hormonal theory : The level of progesterone is very high during pregnancy. But there is a fall in this level just before labor starts - either due to more free estrogens which suppress the progesterones or due to decreased secretion. This low level is believed to initiate labor.
- Fetal Cortisol Theory: The fetal brain secretes increased levels of the hormone cortisol when it becomes mature. This suppresses progesterones and initiates labor. This theory has been proved to cause onset of labor in sheep.
- Hyperdistension of the uterus: In late pregnancy, distension of the uterus causes the uterine muscles to secrete a chemical known as prostaglandin which stimulates contraction of the muscles. This explains the preterm labour in case of multiple pregnancy and polyhydramnios.
Prodromal Stage of Labour
Normal labor is usually preceded by a stage of pre-labour in the last weeks of pregnancy in which clinical symptoms known as Prodromal Symptoms occur. These are:
Stages of Normal Labour
Normal labor is divided into three stages.
Stage I lasts from the onset of labour to full dilation of the cervix. In a woman in her first pregnancy, this stage lasts for about 10 to 12 hours. In a woman who has delivered earlier, it lasts from 6 to 8 hours.
Stage II starts from full dilation of the cervix to the delivery of the baby. And Stage III is the stage of delivery of the placenta.
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