Labor

Definition

Labor is the physiological process by which a fetus is expelled from the uterus during childbirth. It involves a series of rhythmic uterine contractions that gradually dilate the cervix and push the fetus through the birth canal, ultimately resulting in the delivery of the newborn.

5 Must Know Facts For Your Next Test

1. Labor is typically divided into three stages: the first stage involves cervical dilation, the second stage involves the expulsion of the fetus, and the third stage involves the delivery of the placenta.
2. The onset of labor is marked by regular, rhythmic uterine contractions that gradually increase in frequency, duration, and intensity over time.
3. The cervix must dilate from a closed position to about 10 centimeters to allow the fetus to pass through the birth canal during the first stage of labor.
4. The second stage of labor begins when the cervix is fully dilated and ends with the delivery of the newborn, which is typically aided by the mother's pushing efforts.
5. The third stage of labor involves the delivery of the placenta, which typically occurs within 30 minutes of the newborn's delivery.

Review Questions

• Describe the three stages of labor and the key events that occur in each stage.
  • The three stages of labor are: 1) The first stage, which involves cervical dilation as the uterus contracts rhythmically to gradually open the cervix; 2) The second stage, which begins when the cervix is fully dilated and ends with the delivery of the newborn, often aided by the mother's pushing efforts; and 3) The third stage, which involves the delivery of the placenta, typically within 30 minutes of the newborn's birth. Each stage plays a crucial role in the expulsion of the fetus during childbirth.
• Explain how the uterine contractions change in frequency, duration, and intensity over the course of labor.
  • As labor progresses, the uterine contractions become more frequent, longer in duration, and stronger in intensity. This gradual increase in contraction strength and frequency is what drives the dilation of the cervix and the descent of the fetus through the birth canal. The intensifying contractions are a key physiological mechanism that propels the baby out of the uterus and through the vagina during the different stages of labor.
• Analyze the role of the cervix during the labor process and how its dilation facilitates the delivery of the newborn.
  • The cervix, the lower part of the uterus, plays a critical role in the labor process. During the first stage of labor, the cervix must gradually dilate from a closed position to about 10 centimeters to allow the fetus to pass through the birth canal. This cervical dilation is achieved through the rhythmic contractions of the uterus, which apply pressure and force the fetus downward. Once the cervix is fully dilated, the second stage of labor begins, enabling the expulsion of the newborn. The progressive dilation of the cervix is therefore a key physiological event that enables the successful delivery of the baby during childbirth.

Related terms

Contractions: The rhythmic tightening and relaxing of the uterine muscles that propel the fetus through the birth canal during labor.

Cervical Dilation: The gradual opening of the cervix, the lower part of the uterus, to allow the passage of the fetus during labor.

Expulsion: The final stage of labor where the fetus is pushed out of the uterus and through the birth canal, resulting in the delivery of the newborn.